COMT Val 158 Met polymorphism is associated with cognitive flexibility in a signal discrimination task in schizophrenia.

BACKGROUND: Associations between the well-known functional single nucleotide polymorphism Val (158)Met in the gene encoding catechol- O-methyltransferase (COMT) and cognitive do-mains affected in schizophrenia are inconsistent regarding directionality and specific impact and call for a more fundamental cognitive endophenotype. Recent studies suggest that the COMT genotype contributes to cognitive flexibility, a fundamental cognitive ability that potentially influences an individual's performance in a variety of other neurocognitive tasks. METHODS: We investigated the association between COMT Val (158)Met genotype and cognitive flexibility as assessed by signal discrimination in the Continuous Performance Test - Identical Pairs version in a cohort of 111 German schizophrenic patients. RESULTS: COMT genotype was significantly associated with signal discrimination index d' in schizophrenia. The Val/Val genotype was associated with the highest and the Met/Met genotype with the lowest scores; heterozygous individuals displayed an intermediate performance. CONCLUSIONS: Our data suggest that allelic variation at the COMT Val (158)Met locus may influence signal discrimination capacity in schizophrenia and confirm that Val loading, probably due to decreased prefrontal dopamine availability, is associated with greater cognitive flexibility, which in turn may influence other cognitive measures that have been associated with COMT to date.

Psychopathological and behavioral correlates of dopaminergic sensitivity in alcohol-dependent patients.

OBJECTIVES: To explore 2 facets of dopamine receptor sensitivity in alcoholics: (1) whether reduced sensitivity of central dopamine receptors is correlated with anxiety, depression, or novelty seeking and (2) whether this reduction is associated with poor treatment outcome. METHOD: Sixty-four alcohol-dependent patients were assessed according to their clinical outcome, sensitivity of central dopamine receptors (apomorphine-induced growth hormone secretion), mood states, and personality traits before and after detoxification. RESULTS: Patients with poor treatment outcome displayed a blunted growth hormone response before, but not after, detoxification. Growth hormone response was not significantly correlated with novelty seeking. Relapsing patients tended to be less depressed than patients who remained abstinent during observation. CONCLUSION: This study did not support the hypothesis that reduced sensitivity of dopamine receptors is associated with anxiety, depressed mood, or high novelty seeking in alcoholism.

Prenatal origin of separate evolution of leukemia in identical twins.

Several studies involving identical twins with concordant leukemia and retrospective scrutiny of archived neonatal blood spots have shown that the TEL-AML1 fusion gene in childhood acute lymphoblastic leukemia (ALL) frequently arises before birth. A prenatal origin of childhood leukemia was further supported by the detection of clonotypic immunoglobulin gene rearrangements on neonatal blood spots of children with various other subtypes of ALL. However, no comprehensive study is available linking these clonotypic events. We describe a pair of 5-year-old monozygotic twins with concordant TEL-AML1-positive ALL. Separate leukemic clones were identified in the diagnostic samples since distinct IGH and IGK-Kde gene rearrangements could be detected. Additional differences characterizing the leukemic clones included an aberration of the second, nonrearranged TEL allele observed in one twin only. Interestingly, both the identical TEL-AML1 fusion sequence and distinct immunoglobulin gene rearrangements were identified on the neonatal blood spots indicating that separate preleukemic clones evolved already before birth. Finally, we compared the reported twins with an additional 31 children with ALL by using the microarray technology. Gene expression profiling provided evidence that leukemia in twins harbours the same subtype-typical feature as TEL-AML1-positive leukemia in singletons suggesting that the leukemogenesis model might also be applicable generally.

Further evidence of human leukocyte antigen-encoded susceptibility to clozapine-induced agranulocytosis independent of ancestry.

To further examine the human leukocyte antigen (HLA)-encoded genetic susceptibility to clozapine-induced agranulocytosis (CA) we performed HLA-genotyping in a sample of German schizophrenic patients, who suffered from this haematotoxic side-effect. Thirty-one schizophrenic patients with CA (17 women and 14 men) and 77 schizophrenic comparison subjects (40 women and 37 men) were included in the study. HLA-genotyping included identification of major histocompatibility complex (MHC) class I (HLA-A, B, Cw) and class II (HLA-DR, DQ) antigens. CA was significantly associated with HLA-Cw*7 (P<0.02), DQB*0502 (P<0.04), DRB1*0101 (P<0.03) and DRB3*0202 (P<0.02). These HLA-haplotypes are also partly linked to other diseases with a strong genetic background. All other antigens revealed no association to this haematotoxic reaction. In addition, we did not find gender-related effects, whereas age seemed to be a further major risk factor of CA (P<0.0003). Thus, HLA loci may serve as genetic marker to identify subjects of different ethnic subgroups prone to this severe idiosyncratic drug reaction of clozapine. Further studies are needed to investigate whether these associations with CA are due to causal involvement or linkage disequilibrium.

Influence of the dopamine D2 receptor (DRD2) genotype on neuroadaptive effects of alcohol and the clinical outcome of alcoholism.

The present study was performed to test the hypotheses that allelic variants at the human dopamine D2 receptor gene locus (DRD2) confer susceptibility to alcoholism or are associated with clinical subtypes of alcoholism. We investigated an A --> G substitution polymorphism in the 3'-untranslated region of exon 8 (E8) of DRD2 with allele frequencies of f(G) = 0.295 - 0.329. No significant association of the DRD2 genotype or allele frequencies with alcoholism was found in an association study including 283 alcoholics and 146 non-alcoholic controls. However, the frequent homozygous E8 A/A genotype with f(AA) = 0.47 - 0.48 was associated with increased anxiety and depression scores in alcoholics during the follow up after clinical detoxification treatment. In addition, E8 A/A was associated with increased suicide attempts and showed a tendency towards more severe withdrawal symptoms, early relapse and reduced responsiveness to the dopaminergic agonist apomorphine. Regression analysis revealed the DRD2 E8 genotype as the only significant factor determining withdrawal severity in female alcoholics. The findings suggest an influence of the DRD2 genotype on the neuropharmacological effects of chronic alcohol exposure and the clinical course of alcoholism.

Reduced dopaminergic function in alcoholics is related to severe dependence.

With a view to the role of dopamine (DA) systems in reward processes and considering recent studies linking specific alleles at the DA-D2 receptor gene locus with alcoholism (especially with severe types) dopaminergic functions were evaluated in 49 alcoholics using growth hormone (GH) response to DA receptor agonist apomorphine (0.01 mg/kg subcutaneously). neuroendocrine testing was performed (during intoxication) at the time of admission to an inpatient alcohol treatment program and was repeated 7 days later (in a postintoxicated state). Patients underwent clinical examination, detoxification treatment and a subsequent rehabilitation program for abstinence including follow-up evaluation of outcome for 6 months. A two-factor analysis of variance (ANOVA) revealed a significant change of GH response (peak values corrected for baseline) over time (between intoxication and postintoxication; p < 0.001) and between abstainers and relapsers (p = 0.032). Relapse was also associated with paternal alcoholism, early onset of disease, and a more complete dependence syndrome and cerebellar atrophy. Standardized canonical discriminant coefficient was highest for reduced GH response compared to other relapse predictors in the model used. It is concluded that reduced GH response to dopaminergic stimulation corresponds to a progressed stage or syndrome of severe alcohol dependence; however, if reduced, dopaminergic function is one cause or consequence of addiction in this particular subgroup of patients that remains to be elucidated.

Combined dexamethasone/corticotropin-releasing hormone test in acute and remitted manic patients, in acute depression, and in normal controls: I.

Hypothalamic-pituitary-adrenal system (HPA)-function in patients with mania (n = 11), depression (n = 11, unipolar) and in control subjects (n = 11) was studied; six of the acutely manic patients were reevaluated after a symptom-free interval of at least 6 months. The combined dexamethasone-suppression/human CRH-challenge test was used to probe HPA-system function. After CRH and dexamethasone pretreatment, ACTH and cortisol release were significantly increased in both manic and depressed patients in comparison to the control group. In the remitted patients with mania, a significant decrease in hormonal release after DEX and CRH was evident when compared to the acute manic episode, but the degree of CRH-stimulated hormone secretion in these remitted patients was still significantly larger than in normal controls. This study demonstrates that acute and remitted manic episodes are associated with a profoundly dysregulated HPA-system activity.

Combined dexamethasone/corticotropin-releasing hormone test in patients with schizophrenia and in normal controls: II.

Hypothalamic-pituitary-adrenal system (HPA) function was tested in 24 patients with schizophrenia and compared to 24 age-matched healthy volunteers using the combined dexamethasone-suppression (DST/CRH) corticotropin-releasing hormone stimulation test (DST/CRH). After stimulation with CRH, the dexamethasone-pretreated patients released significantly more cortisol, but a similar amount of adrenocorticotropic hormone (ACTH) in comparison to controls. No association between DST status and degree of severity of illness and/or current medication was found. However, in comparison to unmedicated patients, those patients currently receiving antipsychotics, who were also those with a lesser degree of severity of illness, showed a decreased release of CRH-stimulated cortisol and ACTH. This study demonstrates that schizophrenic patients have a dysregulation of the HPA system as assessed with the DEX/CRH test. Overall, however, the degree of HPA-system dysfunction in schizophrenic patients seems to be of a lesser magnitude than in patients with affective disorders.

Age-associated changes of pituitary-adrenocortical hormone regulation in humans: importance of gender.

In the present study the hypothesis was tested that in normal human aging an insensitivity of the glucocorticoid feedback signals is acquired. Thus, 40 healthy elderly (mean age: 69 +/- 5 years) and 20 younger (mean age: 34 +/- 8 years) individuals underwent a combined dexamethasone suppression/CRH-stimulation test. Cortisol secretion after dexamethasone (DEX) pretreatment and before CRH was increased in the older age group, but none of the subjects escaped DEX-induced suppression of cortisol. However, after additional CRH administration to the DEX-pretreated volunteers, the older group released significantly more cortisol than their young counterparts. Within the group of the elderly only, a positive correlation between BASAL, DEX-pretreated cortisol concentration and post-CRH steroid responses was found. Gender profoundly affected DEX/CRH-test outcome: females, regardless of age, had an increased hormonal secretion in comparison to males. It is concluded that, during human aging, adaptive changes in glucocorticoid receptors take place, allowing for the system to maintain "peripheral" glucocorticoid homeostasis, but that more sophisticated challenge procedures such as the DEX/CRH test reveal an age-related increase in HPA system activity.

Flavin monooxygenase 3 (FMO3) polymorphism in a white population: allele frequencies, mutation linkage, and functional effects on clozapine and caffeine metabolism.

AIM: The flavin-containing monooxygenase 3 (FMO3) has been shown to be genetically polymorphic. In vitro, the enzyme contributes to the N-oxidation of clozapine, caffeine, and several other drugs. We therefore wanted to analyze population frequencies and allelic linkage of FMO3 mutations and their functional effect on the metabolism of clozapine and caffeine. METHODS: This study included 204 patients treated with clozapine for schizophrenia and 192 healthy volunteers receiving a 100 mg oral test dose of caffeine. FMO3 polymorphisms M66I, P153L, E158K, V257M, E305X, E308G, and R492W were analyzed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. Ratios of serum clozapine N-oxide over clozapine and of urine theobromine versus paraxanthine were used as in vivo indicators of FMO3 activity. RESULTS: From the known FMO3 amino acid variants, only K158 (frequency 0.426), G308 (0.225), and M257 (0.069) were found; mutations I66, L153, X305, and W492 were not found in the 396 subjects. Linkage analysis revealed seven different alleles; the most frequent of these was the wild-type E158-V257-E308 (0.534), followed by K158-V257-G308 (0.199) and K158-V257-E308 (0.192). Subjects with these frequent variants of FMO3, however, did not differ in clozapine N-oxidation or caffeine oxidation compared with the wild-type. CONCLUSION: There are several genetic polymorphisms for the FMO3 enzyme. The effects on the metabolism of caffeine or clozapine could not be shown, indicating that the mutations have only minor functional effects or that substrate affinity is too low to be clinically relevant.

Dopaminergic responsivity in alcoholism: trait, state, or residual marker?

OBJECTIVE: In order to classify neuroendocrine abnormalities in alcohol-dependent patients as trait, state, or residual markers, growth hormone (GH) secretion was assessed longitudinally. METHOD: GH secretion, stimulated by the dopaminergic agonist apomorphine, was evaluated in 21 alcohol-dependent patients (16 men, five women) and 10 healthy comparison subjects (eight men, two women). The patients were tested during early withdrawal, after 8 days of abstinence, and after 3 months. RESULTS: Patients who relapsed within 3 months (N = 8) showed significantly less GH secretion in all neuroendocrine tests than did either the patients who abstained from ethanol consumption for 6 months (N = 13) or the healthy comparison subjects. The relapsers and abstainers did not differ significantly in any of their clinical or pathophysiological data, in the severity of their withdrawal symptoms, or in antecedent or concomitant illnesses associated with alcoholism. CONCLUSIONS: GH blunting appears to be a residual marker of clinical relevance in alcoholism.

Pituitary-adrenal-system regulation and psychopathology during amitriptyline treatment in elderly depressed patients and normal comparison subjects.

OBJECTIVE: This study was done to compare the effects of 6-week treatment with amitriptyline on hypothalamic-pituitary-adrenocortical (HPA) regulation in elderly depressed patients and age-matched comparison subjects. METHOD: A combined dexamethasone-suppression/CRH-stimulation (dexamethasone/CRH) test was administered before initiation of amitriptyline treatment and at the end of weeks 1, 3, and 6 of treatment. Thirty-nine depressed inpatients, mean age = 69 years, completed the study. Fourteen normal volunteers, mean age = 67 years, served as comparison subjects. RESULTS: In relation to the comparison subjects, the depressed patients had a profoundly abnormal HPA response, in particular an exaggerated cortisol release in the dexamethasone/CRH test. This abnormality began to disappear after 1 week of treatment with amitriptyline. In contrast, amitriptyline did not affect neuroendocrine regulation in the comparison subjects at any time during the test period. CONCLUSIONS: The data suggest that amitriptyline affects HPA regulation in hypercortisolemic depression only, and they raise the possibility that normalization of its feedback control is related to the antidepressive effect of amitriptyline.

Long-term therapeutic drug monitoring of clozapine and metabolites in psychiatric in- and outpatients.

RATIONALE: Clozapine is a unique antipsychotic drug, outstanding for its lack of extrapyramidal side-effects and its superior efficacy in refractory schizophrenia. However, an unambiguous concentration-response relationship has not yet been established. OBJECTIVE: We investigated serum concentrations of clozapine, norclozapine and clozapine-N-oxide in psychiatric in- and outpatients to identify particular metabolic patterns in clozapine responders and non-responders and putative threshold levels for clozapine response. METHODS: Psychiatric assessments, CYP2D6 genotype, and weekly serum concentrations of clozapine, norclozapine and clozapine-N-oxide were obtained in 34 adult schizophrenic in-and outpatients (18 men, 16 women) during 10 weeks of clozapine treatment with a naturalistic dose design. RESULTS: Responders (n=21) displayed significantly lower serum concentrations of clozapine corrected for dose compared to non-responders (n=13; P<0.05), while none of the other parameters (absolute clozapine concentration, metabolite ratios, gender) were different. Smokers had significantly lower dose-corrected clozapine concentrations. A positive correlation was observed between age and average steady state clozapine concentrations. CONCLUSIONS: These findings indicate a possible link between CYP activity and response to clozapine that is not mediated through differences in serum concentrations. No clinically meaningful pattern in serum parameters could be identified that differentiates responders from non-responders. Thus, clozapine TDM seems ineffective for predicting clinical response. Smoking behavior is a major determinant of clozapine clearance while CYP2D6 genotype does not impact clozapine disposition.

Clozapine-induced agranulocytosis in schizophrenic Caucasians: confirming clues for associations with human leukocyte class I and II antigens.

Clozapine-induced agranulocytosis (CA) is still among the least understood adverse drug reactions in psychopharmacology. In particular, its genetic background is far from being clarified. Within the framework of a case-control study, we performed human leukocyte antigen (HLA) genotyping and haplotype analyses in 42 non-Jewish Caucasian schizophrenic patients (N=42) suffering from CA and 75 non-Jewish Caucasian schizophrenic patients treated with clozapine without developing CA. While controlling for age (P<0.0001) and sex (P=0.835), testing of the alleles from both HLA-loci resulted in borderline results for Cw2 (P=0.085, odds ratio (OR)=0.36, 95% confidence interval (CI): 0.08-1.23), Cw7 (P=0.058, OR=2.0, 95% CI: 0.87-4.63) and DRB5*0201 (P=0.005, adjusted OR=22.15). For haplotype analysis, we obtained significant association results with CA for the two-locus haplotypes HLA-Cw-B (P=0.022) and HLA-DRB5-DRB4 (P=0.050), and for the three-locus haplotype HLA-Cw-B-DRB5 (P=0.030). The complex nature of CA implies that many genes might play a role, but currently, only HLA associations with CA are identified as clinically relevant.

[Diabetes and depression]. / Diabetes und Depression.

Cohort studies indicate a high prevalence of depression in patients with diabetes mellitus. Despite numerous investigations, the underlying pathophysiologies of the metabolic abnormalities are poorly understood. A possible role play the increased counter-regulatory hormone release involved in glucose homeostasis, alterations in the glucose transport function and increased inflammatory activation triggered by depression. The diagnose of "depression" in diabetic patients might be hampered by similar symptoms of both conditions as fatigue, psychomotor inhibition, reduced appetite or sexual dysfunction. In treating depressive patients with diabetes one should consider potential induction or worsening of diabetes-like metabolic alterations. Selective serotonin-reuptake-inhibitors, venlafaxin and MAO-Inhibitors constitute a beneficial choice. Atypical antipsychotics like clozapine, olanzapine, quetiapine and risperidone should be given with precaution due to potential effects on glucose homeostasis.

[Health economic aspects of medical care and therapeutic options for schizophrenic and depressive patients in Germany]. / Medizinische Versorgung und therapeutische Optionen unter gesundheitsökonomischen Aspekten bei psychiatrischen Patienten in Deutschland am Beispiel schizophrener und depressiver Störungen.

Optimal and effective medical care of patients suffering from psychiatric disorders and their integration into society leads undoubtedly not only to a higher quality of life of the person affected, but also to a reduction of direct and indirect disease-related costs such as loss of earnings and disability pension. Both schizophrenia and depressive disorder display an early age of onset and inclination to a chronic course under inadequate medical care and thus are interesting examples for diseases with enormous direct and indirect disease-related health costs. We want to illustrate with these diseases the necessity for further effort, more extensive financial support, and the will for change to maintain the standard of medical care for psychiatric patients which has been achieved during the last 20 years in Germany. To achieve this goal, all sectors of the healthcare system have to recognize the health economic effects of inadequate medical care of psychiatric patients either as a result of understaffing, insufficient application of therapeutic options, inadequate exploitation of the care system, or as an effect of inaccurate legislation and to draw the right conclusions together. Furthermore, more research on the care system of psychiatric patients dealing with economic aspects is required.

Neuroleptic malignant syndrome in a patient with succinic semialdehyde dehydrogenase deficiency.

A patient suffering from a rare enzyme deficiency developed a malignant neuroleptic syndrome after having been treated with one single dose of haloperidol. We investigated the patient's serum for all frequent polymorphisms in cytochrome P450 2D6, assuming him to be a poor neuroleptic metabolizer. We will also discuss other potential mechanisms inducing this disturbance and its differential diagnoses.

Genetic determinants of drug-induced agranulocytosis: potential risk of olanzapine?

Whether or not olanzapine causes bone marrow toxicity is still a matter of debate. In spite of pre-marketing and post-marketing clinical trials, and although there have been no cases in animals of olanzapine-induced neutropenia or agranulocytosis, the risk of bone marrow toxicity cannot be excluded. The present paper addresses the following questions: what is the potential background of drug-induced agranulocytosis? Are there any case reports supporting the view that olanzapine has relevant bone marrow toxicity? What strategies might be helpful in identifying the pathological mechanisms underlying this side effect?