By D. Kafa. West Virginia University Parkersburg. 2019.
Siever: Psychiatry Service purchase cheap etodolac line, Bronx Veterans Affairs Medical Cen- not placebo etodolac 300 mg otc, reduced impulsive aggressive behavior in prison ter order etodolac 400 mg line, Bronx cost of etodolac, New York. Adirect relationship between lumbar patients with low lumbar cerebrospinal fluid (CSF) concen- CSF 5-HIAA concentration and aggression in these subjects trations of 5-hydroxyindolacetic acid (5-HIAA). This work suggests that aggressiveness may be associated with increased led to a large number of subsequent studies, using a variety (rather than decreased) intrasynaptic concentrations of 5- of 5-HT measures, designed to test the 5-HT hypothesis HT. These data could be consistent with a deficiency hy- of aggression further. If postsynaptic 5-HT function is unchanged (or increased), however, these data 5-HT and Aggression: CSF 5-HIAA Studies would suggest increased 'net' 5-HT function in these sub- Brown et al. Evidence examining these hypotheses is discussed in tween CSF 5-HIAA and a life history of aggression (r the following sections. This finding was replicated in a follow-up study using another variable reflective of aggression (i. In both samples, a trivariate relationship between re- duced CSF 5-HIAA and aggression and suicidal behavior Coccaro et al. Later reports demonstrated that reduced mine (PRL[D,L-FEN]) response in drug-free mood-disor- CSF 5-HIAA was specific to impulsive rather than premedi- dered and personality-disordered patients compared with tated (i. In addition, patient subjects first demonstrated that CSF 5-HIAA among violent of- with a history of a suicide attempt displayed blunted fenders whose index crime was classified as 'impulsive' (i. Personality-disordered, but not mood-disordered, violent offenders whose index crime was classified as 'non- patients also displayed an inverse relationship between var- impulsive' (i. The hypothesis that 'impulsiveness' is the key behav- and PRL[D,L-FEN] responses. Because experimental reduc- ioral correlate of reduced 5-HT activity was later advanced tion in norepinephrine (NE) activity has been shown to in a series of studies from Virkkunen et al. In eliminate the expected aggressive behavior of animals with these studies, CSF 5-HIAA concentrations of 'impulsive' reduced 5-HT (28), a reduction in NE system function in arsonists were reduced to the same degree as in 'impulsive the mood-disordered (29), but not the personality-disor- violent offenders' and were significantly lower than those dered (30), subjects could have mitigated the influence re- observed in healthy volunteers. Because both impulsive ar- duced 5-HT function could be expected to have on the sonists and impulsive violent offenders had (theoretically) expression of aggressive behavior. For the depressed patient, 'impulsivity' in common, these investigators proposed that reduced NE system function may be associated with a re- the key correlate to reduced CSF 5-HIAA was impulsivity as duction in efficiency to attend to novel (e. Further study noted that PRL[D,L-FEN] responses accordingly, it may be premature to conclude that the key were inversely related to CSF 5-HIAA and were directly behavioral correlate of reduced central 5-HT function is related to PRL[meta-chlorophenylpiperazine or m-CPP] re- impulsivity rather than a combined construct of impulsive sponses, an index of postsynaptic receptor activation (25). An inverse relationship between CSF 5-HIAA When these 5-HT measures were examined in the same and aggression or impulsivity has also been reported in male personality-disordered subjects, a relationship between 5- patients with alcoholism (17), in behaviorally disruptive HT and aggression was noted for both PRL[D,L-FEN] and male children and adolescents (18), and in rhesus (19) and PRL[m-CPP] responses (which were also directly corre- pigtailed macaques (20). The reason probably is the presence tivity of the postsynaptic 5-HT receptor. Available data sug- of subjects who are less severe in their aggressive behavior. Studies ex- with alcoholism (38,39), suicidal patients (40), violent of- amining the platelet 5-HT2A receptor in aggression are few, fenders (41), healthy volunteers from the community (42), and results are mixed, with one study reporting no relation- and macaques (43). Nonreplication studies involve subjects ship (61), another reporting a negative relationship (62), with history of primarily nonalcoholic substance abuse (44, and yet another reporting a positive relationship (63) be- 45) and children with disruptive behavior disorders (46, tween this 5-HT receptor and aggression. Whole-blood 5-HT concentrations have been is possible that nonalcoholic drugs of abuse modify the neu- reported as elevated in juvenile offenders compared with robiological substrate of subjects so correlations between 5- normal control subjects (64) and as a function of age of HT and measures of impulsive aggression are direct rather onset (65). Apositive correlation between platelet 5-HT than inverse, as are seen in patients with alcoholism (38, concentration and measures of aggression in adult depressed 39). In children, two studies reported a positive correlation patients (66) has also been reported. Negative studies, how- between aggression and PRL[D,L-FEN] response (46,47), ever, include those performed in mentally retarded adults and one reported a negative correlation between aggression (67) and in children with attention-deficit/hyperactivity dis- and thermal [D,L-FEN] responses (50). The ratio of plasma tryptophan to other compet- older children, two studies reported no correlation between ing neutral amino acids was lowest among patients with PRL[D,L-FEN] and aggression (48,49). It is possible that alcoholism with a history of depression or aggression and changes in the 5-HT system occurring over development was lowest among those patients with alcoholism with a affect the nature of the 5-HT–aggression relationship in history of both depression and aggression in two studies that this relationship is positive in some 5-HT–mediated (69,70). Other studies reported elevated levels of plasma pathways, such as the PRL[D,L-FEN] response, in prepuber- tryptophan (or the tryptophan ratio to neutral amino acids) tal children, is absent in postpubertal children, and is inverse in violent offenders (71,72) or positive correlations with in adults. The neurobiological mechanisms underlying this aggression in healthy volunteers (73). Behavioral measures of aggression have been available for many years and include paradigms in which subjects are instructed to deliver a noxious stimulus (e. The platelet sion Paradigm or PSAP) (75), 'confederate' subjects under 5-HT transporter (or 5-HT uptake activity) has been as- specific social conditions. In a study of 14 male personality-disor- children and adolescents include the studies of Stoff et al. Another study reported a similar finding with adult subjects, three of four studies reported inverse rela- respect to 5-HT1A receptor function (36). In this study, tionships between platelet 5-HT transporter binding and high PSAP ('high aggressive') responders had blunted ther- aggression or impulsivity in personality-disordered subjects mal responses to ipsapirone challenge compared with low (55,56) and aggressive institutionalized adults (57); the PSAP ('low aggressive') responders. Two studies examined the ducted in research volunteers without documented psycho- function of the platelet 5-HT transporter, with one demon- pathology. Four studies in which brain 5-HT was putatively strating a reduction of platelet 5-HT uptake in aggressive manipulated by tryptophan depletion, supplementation, or adult subjects and an inverse relationship with impulsivity both (76–79) reported data consistent with an inverse rela- (59), and a second study demonstrating no differences in tionship between 5-HT activity and aggressive responding 1712 Neuropsychopharmacology: The Fifth Generation of Progress in the laboratory, although one suggested that this effect is was also present in each of these studies. Because CSF 5- restricted to a subgroup of aggressive subjects (79). The one HIAAmay 'drive' CSF HVA(87), it is possible that these negative study in this area did not use a laboratory paradigm findings are related to a more primary relationship between in which provoked aggression could be assessed (80). Conversely, an imaging study ies in which 5-HT activity was acutely increased by using of striatal dopamine transporters in human subjects re- either single doses of D,L-FEN or of the 5-HT1A/1B agonist ported greater heterogeneity in these receptors in impulsive eltoprazine (34,81) reported a reduction in aggressive re- violent offenders compared with control subjects (88), a sponding on behavioral paradigms. For D,L-FEN, but not finding suggesting that a reduction in CSF HVAmay not eltoprazine, this result was specific to aggressive responding be secondary to alterations in 5-HT function. These data are consistent with clinical trial data using 5-HT enhancing agents, dis- Neurosteriods cussed later (82). Testosterone Catecholamines Testosterone and related androgens generally play a facilita- tive role in aggressive behaviors (see refs. Positive correlations between plasma testosterone dopaminergic (DA) activity could be hypothesized to facili- concentrations and measures of aggression have been re- tate aggressive responding in humans (83,84). Correlations have droxyphenylglycol (MHPG), but not CSF homovanillic also been reported in volunteers between reports of relatives acid (HVA), concentrations and life history of aggression and spouses of their global aggressive behavior and both (12). Further analysis revealed, however, that CSF 5-HIAA testosterone and NE (92), and basal testosterone levels have accounted for 80% of the variance in aggression scores. However, significant reduc- higher in psychiatric and criminal populations characterized tions in CSF MHPG in impulsive violent offenders was by high aggression. For example, male criminals with per- reported in one study (15), although not in a later study sonality disorders had significantly higher levels of circulat- by the same investigators with a much larger sample (8). Plasma concentrations of testosterone and self-reported 'irritability' (a correlate of aggression) in a small sample of male personality-disordered and healthy appear to be higher in persons with alcoholism with a his- volunteer subjects (30). Arole of -NE receptors in aggres- tory of repeated episodes of domestic violence than in com- 2 sion has been suggested by animal data in which the intrahy- parison groups (95). In criminal offenders, higher CSF tes- pothalamic injection of -NE agents enhances aggressive tosterone concentrations were found in antisocial impulsive 2 responding in the cat (86). The authors suggested that one violent offenders, but they were not found in nonantisocial putative mechanism underlying this finding could involve impulsive or nonimpulsive violent offenders, in comparison stimulation of -heteroceptors on presynaptic 5-HT neu- with a healthy volunteer control group. There are some reports from in prospective, blinded Support for a DAhypothesis of human aggression is studies suggesting that administration of exogenous testos- also limited. Although some studies reported no relationship terone may result in aggressive behaviors (96), but the per- between CSF HVAand aggression (12,15), other studies centage experiencing severe mental disturbances is likely to suggested the presence of an inverse relationship between be small (97–99). Anabolic steroid administration may not these variables. Areduction in CSF HVAin antisocial, be uncommon among prisoners (100), and it may induce though not 'explosive,' impulsive violent offenders was re- abnormal personality traits in body builders (101). Areduction in CSF HVAhas also istic studies of testosterone concentrations are limited in been reported among recidivist violent offenders in compar- their interpretation because of the pulsatile nature of testos- ison with nonrecidivist violent offender controls (16), a terone release, so particularly plasma concentrations may be finding suggesting that reduced dopaminergic function quite variable, whereas CSF may be more reflective of aver- plays a role in predicting future aggressive behavior. Studies of exogenous steroid administration are findings must be taken with caution, however, because an complicated by, in most cases, the uncontrolled nature of inverse relationship between CSF 5-HIAA and aggression this steroid use.
Comorbidity OCD is often (60-90%; Katzman discount etodolac on line, 2014) co-morbid with other psychiatric disorders (particularly depression and anxiety) and it may be difficult to determine the primary condition buy etodolac in india. It is possible for people with OCD to develop delusions buy etodolac paypal. A diagnosis of OCD is a risk factor for schizophrenia order etodolac 200mg on-line. Recent opinion is that these two conditions probably share common etiological factors (Meier et al, 2014). Personality disorders are highly prevalent among people with OCD. The cluster C personality disorders (avoidant, dependent, obsessive-compulsive) are the most common, but borderline, histrionic and schizotypal also occur. Prognosis 142 children and adolescents with OCD were followed up after 9 years (Heyman et al, 2010). Considerable numbers had developed other psychiatric diagnoses. The highest estimate of spontaneous and enduring remission is 20% (Skoog & Skoog, 1999). Thus, OCD is a chronic disorder with a guarded prognosis. Concordance among monozygotic twins is greater than among dizygotic twins (Browne et al, 2014). Family studies have more consistently demonstrated OCD among the first-degree relatives of patients with childhood onset OCD, than among the first-degree relatives of patients with later onset OCD (Starcevic, 2005). It is assumed that those with early onset OCD have a stronger genetic contribution. Certain OCD symptoms (such as contamination/cleaning) are found in families more commonly than others (such as symmetry/ordering) (Brakoulias et al, 2016). A number of genome-wide linkage studies and 80 candidate gene studies have been published. Single-nucleotide polymorphisms (SNPs) have enjoyed little success (Jaffe et al, 2014). Neuroimaging OCD has been extensively investigated using neuroimaging - a large number of techniques and study designs. Circuits which commence in the cortex, extend to various subcortical structures and finally link back to the cortex have been described – different names are used, sometimes because different structures are involved, and sometimes because different names are used for the same structures. According to this model, disturbances in the pathways between the cortex and the thalamus are implicated in the pathogenesis of obsessions, and abnormalities in the striatum are involved in the pathogenesis of compulsions and repetitive motor acts. A recent study (Moreira et al, 2017) used MRI and presents an integration of structural and functional observations. OCD patients showed volume reductions in the right superior temporal sulcus. They also showed decreased functional connectivity (FC) (the functionally integrated relationship between spatially separated brain regions) in two distinct subnetworks involving: 1) the orbitofrontal cortex, temporal poles and the subgenual anterior cortex, and 2) the lingual and postcentral gyri. Another network, formed by connections between thalamic and occipital regions showed significant increase in FC. Tao et al (2017) are consistent with Moreira et al (2017) above. They describe, in OCD patients, abnormality in the lingua gyrus and the precuneus (part of the post central gyrus). Gan et al (2017) also found widely distributed abnormality of white matter. Thus, it is clear OCD is associated with more widely distributed abnormality than previously grasped. In about half patients with OCD the symptoms commence gradually, usually in childhood. In the other half, symptoms commence after a traumatic event (TE), usually in later life. Patients without TE may have bilateral grey matter volume increases in putamen and the central tegmental tract of the brainstem, while those with TE may have grey matter volume increase in the right anterior cerebellum (Real et al, 2016). Thus, the possibly of different pathophysiologies, depending on etiology. Immune factors An OCD-like disorder is caused in childhood by streptococcal infections - termed PANDAS (Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections). A large percentage of children who have suffered this Pridmore S. A role for immune factors in the aetiology OCD continues to be explored (Rodriguez et al, 2017) Current theories OCD is yet to be fully understood. One recent theory proposes a connection between disgust and OCD. Disgust is a basic human emotion, which may have an evolutionary function: the avoidance of contamination and disease. Functional imaging indicates that the neurocircuitry of OCD and disgust are similar. This would fit with OCD in which there are contamination concerns. Other current theories include “not just right experiences” (Coles et al, 2010), “failure of the ability to terminate improbable but grave danger concerns” (Woody and Szechtman, 2010), “an inflated sense of responsibility” (Smari et al, 2010), an increased sense of “incompleteness” (Belloch et al, 2016), and “difficulties in decision making” (Pushkarskaya et al, 2017). A theory of the molecular etiology of OCD suggests an alteration of dendrite formation, mediated by insulin and insulin-related signalling (van de Vondervoort et al, 2016). Psychological therapy Exposure and response prevention (ERP). Exposure consists of either self- or therapist-guided confrontation with the feared object or circumstances. Response prevention: once confrontation has been achieved, patients are asked to refrain from performing rituals. In thought stopping the patient (or initially the therapist) applies a stimulus which counteracts or interrupts the obsessional preoccupation. Common techniques include shouting “stop” or applying an aversive stimulus such as a sting on the wrist with an elastic band. Eventually, shouting or stinging can be replaced by less dramatic act, such as clenching a fist, at which point thought stopping can be performed unnoticed, in public settings. Behavioural therapy is as effective as pharmacotherapy, and neuroimaging studies show the same changes in cerebral metabolism with successful behaviour therapy as with successful pharmacotherapy (Swartz et al, 1996). However, both are ineffective in 25% of OCD patients. Behavioural therapy has an advantage over pharmacotherapy as the beneficial effects last longer after therapy has ceased. However, behaviour therapy can be difficult to apply if the patient does not have overt rituals (that is, if the symptoms include mental rituals and obsessional slowness). This approach is unacceptable to some patients and ineffective in others. Pharmacological therapy 70% of treatment naïve OCD patients will improve at least moderately with the use of SSRIs (Rasmussen et al, 1993), but most will have residual symptoms and impairments. All SSRIs appear to be effective (Katzman et al, 2014). Treatment of OCD with SSRIs requires larger than the usual antidepressant dose to be sustained for up to 12 weeks for full effect (Kellner, 2010). When response is unsatisfactory, augmentation of an SSRI with an antipsychotic is recommended (Kellner, 2010), in particular, haloperidol, risperidone and aripiprazole. Clomipramine is an older medication, a tricyclic antidepressant (which has a strong serotonin reuptake inhibition action) was the first pharmacological agent to be effective in the management of OCD. Use has declined in favour of the SSRIs, because the newer medications have less side-effects and are less dangerous in overdose. Current opinion is that clomipramine has no therapeutic advantage over the SSRIs, but it retains a role as a second-line agent, applied when the response to SSRIs has been unsatisfactory (Katzman et al, 2014). The relapse rate is very high (24-89%; Abramowitz et al, 2009). Neurosurgery At least 10% of OCD cases are resistant to conventional therapy (Moon et al, 2017). Cingulotomy, disconnecting the outflow of from the orbitofrontal cortex, has been reported to be effective, sustained and safe. Deep brain stimulation (DBS) offers a clinical response of 60% (Bais et el, 2014).
A renal ultrasound scan is always necessary before undertaking a renal biopsy purchase etodolac australia. Ultrasound scanning cannot exclude the diagnosis of autosomal dominant polycystic kidney disease in people under the age of 20 and is therefore of limited use in people under this age with a family history of this condition order discount etodolac on-line. The GDG agreed that before undertaking a renal ultrasound scan in people at risk of kidney disease on the basis of a family history of inherited kidney disease order discount etodolac online, it was important that people were fully informed of the implications of an abnormal scan result etodolac 400mg sale. This should encompass counselling about the benefits of early identification of kidney disease but should also outline the social consequences of a diagnosis, including its effect on life insurance. Where indicated help to cope with the psychological consequences of a diagnosis should be offered. R19 Advise people with a family history of inherited kidney disease about the implications of an abnormal result before a renal ultrasound scan is arranged for them. To do this we need to know: q what the adverse outcomes are q at what level of GFR we should be alert to adverse outcomes and q the impact of associated factors such as age, gender and presence or absence of proteinuria at any given level of GFR. Large population studies have clearly suggested that the risk of death, hospitalisation and cardiovascular events rises exponentially at levels of GFR below 60 ml/min/1. The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) stratified chronic kidney disease into five stages according to glomerular filtration rate and the presence of kidney damage: q Stage 1: GFR >90 ml/min/1. CKD is common and its prevalence increases markedly with age, with a female predominance. However, the CKD classification is neither staged according to age and gender, nor according to level of proteinuria. All patients, regardless of age, gender and proteinuria or albuminuria are considered to have at least moderately severe CKD when their GFR is <60 ml/min/1. However, we have some evidence that GFR reduces as a consequence of ageing,112 although the exact level of reduction is still a subject of debate, and reduced GFR is very common in certain older populations. Long term, the ABLE study aims to identify the reasons for this faster deterioration. The degree of proteinuria is a significant risk factor both for progression of CKD and for cardiovascular disease. The recently published SIGN (Scottish Intercollegiate Guidelines Network) guideline also makes the same recommendation, as did the UK consensus conference on early CKD which also recommended sub-classifying CKD stage 3 into 2 groups: 3A which defines a lower risk group with GFR 45–59 ml/min/1. Baseline characteristics were significantly different between groups with lower eGFR compared with higher eGFR. People with low eGFR were almost always older, more likely to be female, and had higher prevalence of diabetes and cardiovascular diseases. While statistical analyses in these studies have been adjusted for confounding variables such as age, gender, race, and several comorbidities, it is difficult to identify all variables which could potentially affect the size of the risk. These unknown variables make it impossible to assign cause and effect, and the confidence intervals were sometimes so wide that the associations with eGFR could be spurious. Eight cohort studies examined the association between different eGFR levels and several outcomes of interest in populations with concomitant cardiovascular disease; specifically high-risk hypertension,118 acute myocardial infarction,119,120 heart failure,121 acute coronary syndrome,122 coronary disease,123 coronary artery disease124 and peripheral arterial disease. The mean age of people with higher eGFR (typically >60 ml/min/1. A very large US cohort study (N=1,120,295, follow-up 2. This study was rejected as there was little statistical analysis of the results; only mortality rates were presented. Quality of life outcomes such as cognitive impairment, frailty, and disability were assessed in postmenopausal women124 or in older populations with varying levels of serum creatinine132 or eGFR. The effects of age and gender on mortality and kidney disease progression were examined in people with stage 3 CKD in a Norwegian population study (N=3027, median observation time 3. The prevalence of frailty increased with decreasing GFR (p for trend <0. Black ethnicity and female gender were associated with increased likelihood of frailty. Black race and female gender were associated with increased likelihood of disability. There was NS risk of cognitive impairment at eGFR 45–49 or 30–44 ml/min/1. The risk of mortality was highest in those <60 years old. Again the risk was highest in those <60 years of age. Female gender was associated with an increased change in eGFR compared to men (+0. In an age- and sex- matched cohort, the matched risk ratio was 2. For people with proteinuria and eGFR 30–59 ml/min/1. For people with proteinuria and eGFR 15–29 ml/min/1. For people with proteinuria and creatinine clearance (CrCl) 64. ALL-HAT = Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial; ARIC = Atherosclerosis Risk in Communities; LVEF = left ventricular ejection; MI = myocardial infarction. Not all studies stratified patients according to whether or not they had diabetes and this may affect estimates of the risk of death. The evidence suggested that if the GFR is less than 60 ml/min/1. There was limited evidence about outcomes in older people. However, given that they are at increased absolute risk of mortality and cardiovascular events it was agreed that even small increases in relative risk in older people are of significance. The GDG considered that the evidence suggested that the risk of mortality and cardiovascular events increased considerably when the GFR was less than 45 ml/min/1. This led to the proposal to adopt the sub-division of stage 3 CKD into stages 3A and 3B, defined by an eGFR 45–59 ml/min/1. It was noted that the presence of proteinuria was associated with a doubling of CVD risk and mortality at all levels of GFR. Evidence from longitudinal population studies and from meta-analysis of progression risk and level of proteinuria suggested that an ACR ≥30 mg/mmol should be used as a marker of the increased risk (roughly equivalent to a PCR ≥50 mg/mmol or proteinuria values ≥0. The GDG agreed not to recommend age-related decision points for eGFR. However, it seemed clear that in people aged >70 years, an eGFR in the range 45–59 ml/min/1. R21 For the purposes of this classification define proteinuria as urinary albumin:creatinine ratio (ACR) ≥30 mg/mmol or PCR ≥50 mg/mmol (approximately equivalent to urinary protein excretion ≥0. Identification of high-risk groups can help clinicians monitor renal function and identify people with CKD at an earlier disease stage. Although general population screening may not be cost-effective, targeted screening directed at subgroups of the population who might derive the most benefit from CKD detection was shown to be an effective strategy. This work suggested that a vascular check programme would prevent 4000 people a year from developing diabetes and could also detect at least 25,000 cases of diabetes or kidney disease earlier. In those conditions where the prevalence of CKD is high and the risks of preventable complications are increased, testing for CKD is clearly warranted. The KEEP programme identified people with diabetes and hypertension, or people with a first-line relative (parent, grandparent, brother or sister) with diabetes, high blood pressure or kidney disease as being at high risk of CKD. Are there additional high-risk people who should be tested for CKD? The UK CKD guidelines also included those with a high risk of obstructive uropathy, all forms of CVD, multisystem diseases with the potential to involve the kidney such as SLE, and conditions requiring long-term treatment with potentially nephrotoxic drugs. A cohort study evaluated the risk of developing CKD in people with metabolic syndrome compared to those without metabolic syndrome (N=10,096, follow-up 9 years, Atherosclerosis Risk in Communities (ARIC) study cohort). A family history of ESRD was considered present if an incident ESRD patient reported having either a first-degree (parent, child, sibling) or second-degree (grandparent, aunt, uncle, grandchild, or half-sibling) relative with ESRD. This cohort study was excluded as 27% of the cohort did not have albumin excretion rate measurements and there were significant differences between those whose data were included and those whose data were not. The study mainly assessed the relationship between microalbuminuria and coronary heart disease, rather than ethnicity and the development of CKD.
The nucleus basalis of Meynert provides the major with a frequency of 75% buy cheap etodolac 200mg online, whereas 2 and 4 occur with cholinergic input to the cortex and is important for mem- frequencies of 10% and 15% buy discount etodolac 200mg online, respectively (1) discount 300mg etodolac free shipping. Inheritance ory buy etodolac 400 mg on line, but the variability and timing of cholinergic changes of a single 4 allele increases the risk of AD threefold, suggest that they may not be the key factors in early cogni- whereas homozygosity for 4 is associated with an eightfold tive impairment (35). The amygdala receives prominent increase in risk (49). The Apo E 4 allele appears to lower projections from cortical areas and subcortical areas; degen- the age of onset in persons in their sixties and seventies eration therein is particularly relevant to disease-related im- rather than influence the duration and severity of the dis- pairments in motivated and emotional behavior. There is evidence that the 2 allele confers some pro- cell loss in the noradrenergic locus ceruleus, which richly tection from the development of late-onset AD and Down innervates the cortex, has been associated with depressive syndrome (5). Changes in the serotonergic raphe nuclei and Additional genes that may influence the risk of develop- involvement of hypothalamic nuclei, including the supra- ing late-onset disease are being identified at an increasing chiasmatic nucleus, may explain commonly observed im- pace (49,55,56). Among the possible positive risk factors pairments of sleep and circadian rhythm in AD. Although are common population polymorphisms of the APOE pro- dopaminergic neurons of the ventral tegmentum are se- moter (57) and genes encoding the LDL-receptor–related verely depleted, cell loss is only moderate in the substantia protein (LRP-1) (58–61), 2-macroglobulin (62), FE65 nigra, as reflected by the absence of Lewy body pathology (63,64), very LDL (VLDL)-R receptor (65), the lysosomal and associated extrapyramidal symptoms. The well-docu- protease cathepsin D (66), the lysosomal cysteine protease mented reductions in levels of various neurotransmitters inhibitor cystatin C (67), bleomycin hydrolase (68), and and their receptors (47) are almost certainly a secondary interleukin-1 (1A and B) (69,70). In light of the evidence consequence of the loss or functional deafferentation of that neuronal endocytosis is altered at the very earliest stages these subcortical projection neurons. Apo E, its receptor on neurons (LRP), another LRP ligand ( 2- INITIATION OF CELLULAR PATHOLOGY macroglobulin), and the VLDL receptor all are molecules that traffic through early endosomes as they bring choles- Familial AlzheimerDisease terol or other ligands into the cell. Inheritance of the APOE The identification of genes that, when mutated, cause early- 4 allele accentuates endocytic abnormalities in AD (27). Similarly, cystatin C mutations, which cause the Icelandic form of Pathogenetic Mechanisms in Sporadic hemorrhagic cerebral amyloid angiopathy (71), are key reg- AlzheimerDisease ulators of proteases within the lysosomal system. The endo- However, more than 90% of all cases of AD are not caused cytic pathway is also responsible for the internalization and by single gene mutations, and, in these cases, the origin is initial processing of APP at the cell surface. Although the factors that accelerate to the internalization domain of APP and modulates its -amyloidogenesis in sporadic AD are not established, clues processing to A (72). Early endosomes are also a principal are emerging from studies of genes that influence the risk site of A generation in normal cells and mediate the cellular of developing late-onset AD. Topping the list of factors that uptake of A and APPs (73,74). Sup- risk, in part, by creating additional oxidative stress through porting this hypothesis are studies showing the principal - these same pathways (82). Oxidative damage from these secretase in cells resides largely in endosomes (75) and that and other sources leads to mitochondrial membrane depo- cathepsin D, a protease with -secretase activity (76–79), larization and increased levels of mitochondrial reactive oxy- and other 'lysosomal' proteases that influence A forma- gen species (82a). The resultant oxidative damage to pro- tion become more abundant in neuronal early endosomes teins and membranes activates degradative pathways, when the lysosomal system becomes activated in AD. This notably the lysosomal system (31), and in doing so up- latter effect reflects not only the markedly increased expres- regulates cathepsins and other proteases (83), which have sion of these proteases but also their enhanced targeting been implicated in mechanisms of cell death, A produc- to early endosomes by the cation-dependent mannose-6- tion, and cytoskeletal protein modification (34). Free radi- phosphate receptor (MPR-46), which is also more highly cals subsequently impair the function of glucose and gluta- expressed in AD brain (28,80). When these conditions are mate transporters and damage ion-channel adenosine recreated experimentally in cells by modestly overexpressing triphosphatases (sodium-calcium pumps), thereby reducing MPR-46, A generation is substantially increased (80). A formation could, under pathologic conditions, become Calcium homeostasis is further altered by glutamate and abnormally routed to cellular compartments where they other excitotoxins that stimulate receptor-mediated influx promote A generation. This is one mechanism that ex- of calcium or, in FAD, by mutations of presenilin that lead plains how -amyloidogenesis may be accelerated in spo- to the release of intracellular calcium stores (86,87). Ele- radic AD in the absence of a causative gene mutation. Tau hyperphosphorylation decreases EVOLUTION OF CELLULAR PATHOBIOLOGY its binding to microtubules and promotes loss of microtu- bule stability and impaired axonal transport (89). NFT for- The genetic heterogeneity of AD suggests that the disease mation may compound this effect on transport by imposing may be initiated through distinct cellular cascades, which physical obstructions to the movement of vital organelles then converge on the final common pathways responsible to the axon and synapse. Calcium-activated neutral protease for -amyloidogenesis, neurofibrillary pathology, and, ulti- (calpain) systems, which are highly activated in AD brain mately, neuronal cell death. Secondary and tertiary re- (90,91), contribute to the truncation and breakdown of sponses of the brain to the presence of these neuropathologic cytoskeletal proteins including tau, alter the activity of the lesions may further compromise neuronal function, making protein kinase C cascade, cdk5, and other signaling path- it difficult to establish what is cause or effect. Current hy- ways, and participate in the mechanisms underlying apop- potheses on the cellular pathobiology of AD emphasize dif- totic and necrotic cell death (92,93). Ultimately, in certain ferent aspects of this complex multifactorial process, and, cells, mitochondrial damage leads to the release of cyto- not surprisingly, these 'different' views overlap consider- chrome C, which activates caspases that mediate apoptosis. To illustrate this, three perspectives on cellular patho- FAD-linked PS and APP mutations increase the vulnerabil- genesis are discussed in the following paragraphs; these em- ity of cultured neurons to apoptosis, presumably through phasize metabolic decline, defective cell repair, or A one or more of the metabolic pathways discussed above toxicity as the driving pathophysiologic mechanism in AD. From the metabolic decline perspective, cellular oxidative Complementary to the foregoing metabolic decline per- stress leading to neurodegeneration is a final common path- spective is a cell repair hypothesis, which emphasizes a puta- way of metabolic insults originating from different sources. The neuro- slaught on metabolic function begins with effects of normal trophic actions of APP or its mobilization during neuronal aging and specific genetic factors. For example, aging-re- injury are most relevant here. Cells normally secrete a pro- lated cerebral hypoperfusion leading to reduced brain glu- teolytic derivative of APP, designated APPs, which pro- cose and oxygen utilization impairs energy production at motes neuron growth and increases neuronal survival after the mitochondrial level and promotes the production of free certain types of injury (84). The detection of regional hypometabolism in dramatically increases after neuronal injury, ischemia or oxi- AD patients with mild cognitive impairment suggests that dative stress, head injury, and exposure to toxins (97). Cere- such hypometabolism may not be simply a result of neuro- brospinal fluid levels of APPs, however, may be reduced. Moreover, cerebral Apo E also figures prominently in the processes of cell repair ischemia, coronary artery disease, APP mutations, and some and regeneration by coordinating the mobilization and re- 1226 Neuropsychopharmacology: The Fifth Generation of Progress distribution of cholesterol needed for myelin and neuronal companied by the activation of calpains and kinases acting membrane synthesis (48). Functional synaptic remodeling on cytoskeletal proteins (16,82,84). A is one of various in vivo is markedly compromised in mice lacking the Apo factors that may stimulate the glycogen synthase kinase E gene (98). During regeneration, Apo E expression may pathway, which, among other roles, is involved in both the increase up to 100-fold. The 3 allele seems to be more phosphorylation of tau and still unclarified aspects of pre- effective as a growth-promoting or repair factor than the senilin and APP processing (110). Finally, endocytic uptake 4 allele, which is linked to an increased risk of AD (99). E–cholesterol complexes, a process that is altered at the Thus, the A cascade hypothesis ultimately reaches the earliest stages of AD (27). The increased levels of protease same metabolic endpoints as the metabolic decline hypothe- seen in neuronal early endosomes of the AD brain likely sis, but it distinguishes itself by proposing that A accumu- promote the degradation of internalized molecules and may lation is the germinal event, rather than being a secondary, prematurely abrogate their trophic or nutrient functions. To become a compre- cascade hypothesis, places the A peptide at the center of AD hensive hypothesis of AD pathogenesis, the A cascade hy- pathogenesis based on its neurotoxic properties in either pothesis still must explain the nature of the initial disturb- soluble or fibrillar form. A deposition within senile plaques ance that causes A to accumulate in the 90% of AD cases involves a balance between forces that enhance the overpro- that are not caused by FAD-linked mutations. Most likely, duction and aggregation of A and countervailing forces AD pathogenesis is a multifactorial process, in which A that promote the uptake and degradation of A from the is necessary but not a sufficient factor. FAD-linked mutations cause varying de- grees of A overproduction (97), but they may also favor aggregation by increasing the relative production of A 42 or mutant A forms that aggregate more easily. A aggrega- CONCLUSIONS tion is also facilitated by additional proteins released by reactive or damaged cells (100,100a). In this regard, Apo E In this chapter, a discussion of Alzheimer neuropathology is particularly critical to A deposition (101–103). Cellular provides the starting point for understanding how the diag- uptake and clearance of A involve interactions of an Apo nosis of AD is made and how clinical symptoms arise and E/A complex with LRP. Later sections address the neuroanatomic and cel- loid deposition is underscored by the observation that Apo lular basis for dementia and the molecular events that lead E gene ablation abolishes amyloid deposition in transgenic to neuropathologic lesions and, ultimately, to the death of mice overexpressing APP containing the London mutation neurons. A consideration of current hypotheses on the evo- (104). Microglial function also seems to be critical to A lution of cellular pathology identifies common features that removal (15). In transgenic models of FAD, A deposition help to reconcile the differing views of disease pathogenesis. Although a sequence of events after A deposi- tion has not been confirmed, it is hypothesized that A I am grateful to Janet Rosdil for expert assistance in the accumulation within diffuse plaques eventually leads to local preparation of this manuscript. A -initiated inflammatory and DISCLAIMER neurotoxic processes generate excessive free radicals and per- oxidative injury to proteins and alterations of ionic homeo- Dr. Nixon has received research support from Johnson and stasis, particularly excessive calcium entry into neurons ac- Johnson (Janssen).
10 of 10 - Review by D. Kafa
Votes: 130 votes
Total customer reviews: 130