Molecular differentiation of schizoaffective disorder from schizophrenia using BDNF haplotypes

BACKGROUND

Allelic variation in the gene encoding brain-derived neurotrophic factor (BDNF) has been associated with affective disorders, but generally not schizophrenia. Brain-derived neurotrophic factor variants may help clarify the status of schizoaffective disorder.

AIMS

To test the hypothesis that BDNF haplotypes are associated with psychiatric illness marked by a prominent affective component.

METHOD

Frequencies of a 5-marker BDNF haplotype were examined in 600 White participants across four diagnostic categories and healthy controls.

RESULTS

Individuals with schizoaffective disorder and other affective disorders were significantly more likely to carry two copies of the most common BDNF haplotype (containing the valine allele of the Val66Met polymorphism) compared with healthy volunteers. Moreover, when compared with people with schizophrenia, individuals with schizoaffective disorder were significantly more likely to carry two copies of the common haplotype.

CONCLUSIONS

To our knowledge, this is the first candidate gene study to demonstrate association with schizoaffective disorder but not schizophrenia. Variation in the BDNF gene may be associated with the clinical phenotype of affective dysregulation across several DSM-IV diagnostic categories.

Cognitive effects of memantine in postmenopausal women at risk of dementia: a pilot study

BACKGROUND

To determine the effects of memantine on cognition in a normal population of postmenopausal women with putative risk factors for Alzheimer's disease (AD) using a built-in control for the genetic risk factor for AD (apoE-epsilon4 status).

METHODS

A prospective, open-label, 6-month pilot medication trial with memantine and follow-up after discontinuance conducted at the Center for Neuroscience in Women's Health, Stanford University School of Medicine. Neuropsychological data were collected on 22 community-dwelling postmenopausal women (11 apoE-epsilon4 carriers and 11 apoE-epsilon4 non-carriers) with at least one putative risk factor for AD.

RESULTS

ApoE-epsilon4 status was not a significant predictor of change in neuropsychological performance. Changes associated with memantine treatment for entire sample included significant declines in some variables associated with verbal learning and memory that improved upon medication withdrawal. A positive medication effect was noted with executive functions and possibly category fluency. Trend-level improvements were seen in motor dexterity of the non-dominant hand and maintained even after drug discontinuance.

CONCLUSIONS

Treatment with memantine appeared to have differential effects on cognitive performance in a population of women with putative risk factors for AD. ApoE-epsilon4 carrier status did not account for observed changes in cognition.

Genomic landscape of a three-generation pedigree segregating affective disorder

Bipolar disorder (BPD) is a common psychiatric illness with a complex mode of inheritance. Besides traditional linkage and association studies, which require large sample sizes, analysis of common and rare chromosomal copy number variants (CNVs) in extended families may provide novel insights into the genetic susceptibility of complex disorders. Using the Illumina HumanHap550 BeadChip with over 550,000 SNP markers, we genotyped 46 individuals in a three-generation Old Order Amish pedigree with 19 affected (16 BPD and three major depression) and 27 unaffected subjects. Using the PennCNV algorithm, we identified 50 CNV regions that ranged in size from 12 to 885 kb and encompassed at least 10 single nucleotide polymorphisms (SNPs). Of 19 well characterized CNV regions that were available for combined genotype-expression analysis 11 (58%) were associated with expression changes of genes within, partially within or near these CNV regions in fibroblasts or lymphoblastoid cell lines at a nominal P value <0.05. To further investigate the mode of inheritance of CNVs in the large pedigree, we analyzed a set of four CNVs, located at 6q27, 9q21.11, 12p13.31 and 15q11, all of which were enriched in subjects with affective disorders. We additionally show that these variants affect the expression of neuronal genes within or near the rearrangement. Our analysis suggests that family based studies of the combined effect of common and rare CNVs at many loci may represent a useful approach in the genetic analysis of disease susceptibility of mental disorders.

Catechol O-methyltransferase (COMT) VAL158MET functional polymorphism, dental mercury exposure, and self-reported symptoms and mood

Associations were evaluated between a functional single nucleotide polymorphism (Val158Met) in the gene encoding the catecholamine catabolic enzyme catechol O-methyltransferase (COMT), dental mercury exposure, and self-reported symptoms and mood among 183 male dentists and 213 female dental assistants. Self-reported symptoms, mood, and detailed work histories were obtained by computerized questionnaire. Spot urine samples were collected and analyzed for mercury concentrations to evaluate recent exposures, whereas a chronic mercury exposure index for all subjects was created from the work histories. COMT polymorphism status was determined using a polymerase chain reaction (PCR)-based assay. Scores for current, recent, and chronic self-reported symptom groups and six self-reported mood factors were evaluated with respect to recent and chronic mercury exposure and COMT polymorphism status. Multiple regression analysis controlled for age, socioeconomic status, tobacco and alcohol use, self-reported health problems, and medications. Separate evaluations were conducted for dentists and dental assistants. No consistent patterns of association between either urinary mercury concentration or the chronic index of mercury exposure and any category of symptoms were observed. However, consistent and significant associations were found between increased symptoms and the COMT polymorphism involving the double allelic substitution (full mutation) compared to subjects with no substitutions. Associations with mood were limited to polymorphism status among female dental assistants, and were observed for four of six mood factors and overall mood score. These findings extend evidence of genetic factors potentially affecting human susceptibility to the toxic effects of mercury and other environmental chemicals.

The catechol-O-methyl transferase Val158Met polymorphism and experience of reward in the flow of daily life

Genetic moderation of experience of reward in response to environmental stimuli is relevant for the study of many psychiatric disorders. Experience of reward, however, is difficult to capture, as it involves small fluctuations in affect in response to small events in the flow of daily life. This study examined a momentary assessment reward phenotype in relation to the catechol-O-methyl transferase (COMT) Val(158)Met polymorphism. A total of 351 participants from a twin study participated in an Experience Sampling Method procedure to collect daily life experiences concerning events, event appraisals, and affect. Reward experience was operationalized, as the effect of event appraisal on positive affect (PA). Associations between COMT Val(158)Met genotype and event appraisal on the one hand and PA on the other were examined using multilevel random regression analysis. Ability to experience reward increased with the number of 'Met' alleles of the subject, and this differential effect of genotype was greater for events that were experienced as more pleasant. The effect size of genotypic moderation was quite large: subjects with the Val/Val genotype generated almost similar amounts of PA from a 'very pleasant event' as Met/Met subjects did from a 'bit pleasant event'. Genetic variation with functional impact on cortical dopamine tone has a strong influence on reward experience in the flow of daily life. Genetic moderation of ecological measures of reward experience is hypothesized to be of major relevance to the development of various behavioral disorders, including depression and addiction.

The genetics of mammalian circadian order and disorder: implications for physiology and disease

Circadian cycles affect a variety of physiological processes, and disruptions of normal circadian biology therefore have the potential to influence a range of disease-related pathways. The genetic basis of circadian rhythms is well studied in model organisms and, more recently, studies of the genetic basis of circadian disorders has confirmed the conservation of key players in circadian biology from invertebrates to humans. In addition, important advances have been made in understanding how these molecules influence physiological functions in tissues throughout the body. Together, these studies set the scene for applying our knowledge of circadian biology to the understanding and treatment of a range of human diseases, including cancer and metabolic and behavioural disorders.

Behavioral effects of Bcl-2 deficiency: implications for affective disorders

New hypotheses regarding affective disorders suggest a critical role for cellular resilience and plasticity. Bcl-2 is a central protein in these processes and is elevated by mood stabilizers and antidepressants. In previous studies, mice with targeted mutations of Bcl-2 showed anxiety-related behavioral changes. The present study further explored the relationship between Bcl-2 and behavior using mice with a targeted mutation but with a different background strain than previously tested. Bcl-2 heterozygous mice (B6;129S2-Bcl-2<tm1Sjk>/J) were tested in models of depression, mania and anxiety. Compared to Wild Type (WT) controls, mutant mice showed behaviors modeling two facets of mania: increased reward seeking and amphetamine sensitization. Moreover, the sensitization was attenuated by chronic pretreatment with lithium. In contrast to previous data, the mutation did not affect measures of anxiety. Although data are still minimal, it supports additional studies of the role of Bcl-2 in affective and anxiety disorders. The importance of background strain in behavioral phenotypes of mutant mice is known and the current lack of effect on anxiety measures may be related to high baseline anxiety of WTanimals. More precise studies of Bcl-2 in affective and anxiety disorders will be possible when specific pharmacological modulators of Bcl-2 become available.

Effect of CAG repeat length on psychiatric disorders in Huntington's disease

There is strong evidence that the length of CAG repeats, in patients with Huntington's disease (HD), govern the age of onset and the rate of clinical progression of neurological symptoms. However, psychiatric manifestations of the disease have not been examined as comprehensively. Seventy two Greek patients with Huntington's disease had DNA testing and were clinically assessed by means of a semi-structured interview (SCID) and four self-rated questionnaires. Genotype-phenotype correlations were examined. The CAG repeat length had a significant negative association with the age of onset of psychiatric disorders, the total level of functioning and the MMSE. However, the probability of developing a psychiatric disorder and the severity of psychiatric symptoms were not determined by the trinucleotide expansion, after controlling for the duration of illness, sex, and age of the subjects. The factors that determine the development of psychiatric symptoms in HD patients seem not to be limited to a dose related toxicity of the expanded Huntington. It is hypothesized that alternative genetic or environmental factors underlie the pathogenesis of the psychiatric phenotype.

Family history of completed suicide and characteristics of major depressive disorder: a STAR*D (sequenced treatment alternatives to relieve depression) study

BACKGROUND

Clinicians routinely ask patients with non-psychotic major depressive disorder (MDD) about their family history of suicide. It is unknown, however, whether patients with a family member who committed suicide differ from those without such a history.

METHODS

Patients were recruited for the STAR*D multicenter trial. At baseline, patients were asked to report first-degree relatives who had died from suicide. Differences in demographic and clinical features for patients with and without a family history of suicide were assessed.

RESULTS

Patients with a family history of suicide (n=142/4001; 3.5%) were more likely to have a family history of MDD, bipolar disorder, or any mood disorder, and familial substance abuse disorder, but not suicidal thoughts as compared to those without such a history. The group with familial suicide had a more pessimistic view of the future and an earlier age of onset of MDD. No other meaningful differences were found in depressive symptoms, severity, recurrence, depressive subtype, or daily function.

CONCLUSIONS

A history of completed suicide in a family member was associated with minimal clinical differences in the cross-sectional presentation of outpatients with MDD. Limitations of the study include lack of information about family members who had attempted suicide and the age of the probands when their family member died. STAR*D assessments were limited to those needed to ascertain diagnosis and treatment response and did not include a broader range of psychological measures.

[CADASIL syndrome - cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy]

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited neurodegenerative disease associated with mutations in the Notch 3 receptor on vascular smooth muscle cells. Clinically the syndrome is manifested as migraine, recurrent subcortical ischaemic events, dementia and mood disorders. CADASIL, considered one of the important causes of "subcortical vascular dementia", is relatively easy to overlook or misdiagnose if it is not taken into consideration in differential diagnosis. Diagnosis of CADASIL is established on the basis of results of skin biopsy and genetic examination. In this article we present a short review of the literature concerning pathogenesis and clinical presentation of the syndrome and provide recommendations for detection, diagnosis and management strategies.

[Epidemiology of mood disorders]

The 12 months and lifetime prevalence of is respectively 5 and 9% in the general population; moreover 10 to 20% of general practice patients are depressed. Depression is involved in about 40 to 80% of suicide and induces one of the greatest social burden. Mood disorders are more frequent in women, individual living alone and people with low socio-economic level. Risk factors are stressfull life events, biological vulnerability (genetic factors), somatic diseases, psychiatric comorbidity including personality disorders and addictions. Depressive disorders are underdiagnosed and undertreated despite efficacious pharmacological and psychotherapeutic strategies in their treatment. It's the reason why public health programs to prevent depression have been promoted by many countries like European Alliance against Depression. Their efficacy must be evaluated as their cost-efficiency.

Emotion appraisal is modulated by the genetic polymorphism of the serotonin transporter

We investigated the relationship between the genetic polymorphism of the promoter of the serotonin transporter gene (SLC64A) and emotion appraisal profiles for fear, sadness, and joy in 114 healthy volunteers. Results revealed that carriers of the s-allele achieved higher scores than non-carriers for unpleasantness and goal-hindrance but scored lower for coping ability in the case of fear and sadness. There were no such differences in the case of joy. These results indicate that the s-allele of the serotonin transporter gene is associated with a vulnerable cognitive style related to the appraisal of negative emotions.

Interaction between BDNF and serotonin: role in mood disorders

Brain-derived neurotrophic factor (BDNF) and serotonin (5-hydroxytryptamine, 5-HT) are two seemingly distinct signaling systems that play regulatory roles in many neuronal functions including survival, neurogenesis, and synaptic plasticity. A common feature of the two systems is their ability to regulate the development and plasticity of neural circuits involved in mood disorders such as depression and anxiety. BDNF promotes the survival and differentiation of 5-HT neurons. Conversely, administration of antidepressant selective serotonin reuptake inhibitors (SSRIs) enhances BDNF gene expression. There is also evidence for synergism between the two systems in affective behaviors and genetic epitasis between BDNF and the serotonin transporter genes.

Serotonin receptor 1A C(-1019)G polymorphism associated with premenstrual dysphoric disorder

OBJECTIVE

To assess whether the G allele of the serotonin receptor 1A C(-1019)G polymorphism is associated with premenstrual dysphoric disorder.

METHODS

The study sample comprised 53 women with clinically diagnosed premenstrual dysphoric disorder (age range 27-46 years, mean 37.7 years) and 51 healthy control subjects (age range 22-48 years, mean 36.2 years). The serotonin receptor 1A C(-1019)G polymorphism was genotyped and compared between the two groups.

RESULTS

In contrast to the postulated "high-risk" G/G genotype, there was a marked overrepresentation of the C/C genotype in the premenstrual dysphoric disorder group (P=.034; odds ratio 3.63, 95% confidence interval 1.22-10.78). The presence of at least one C allele was associated with a 2.5-fold increased risk of premenstrual dysphoric disorder (P=.053; odds ratio 2.46, 95% confidence interval 1.03-5.88).

CONCLUSION

Our hypothesis that the high-risk G allele is associated with the occurrence of premenstrual dysphoria was not proved in this study. However, due to the increased prevalence of the C variant, we suggest that the C(-1019) allele may contribute to the risk of premenstrual dysphoria.

LEVEL OF EVIDENCE

II.

Spousal concordance for substance use and anxiety disorders

Assortative mating -- the tendency for mate selection to occur on the basis of similar traits -- plays an essential role in understanding the genetic contribution to psychiatric illness. It also carries significant impact on clinical prognosis and is an important mechanism explaining spousal concordance. This study uses a family study design ascertaining 225 probands with substance abuse/dependence, anxiety disorders, and controls to address: (1) Is there spousal concordance or cross-concordance for substance use and/or anxiety disorders? (2) Is the spousal concordance or cross-concordance associated with worse clinical outcomes? (3) What is the mechanism of the concordance or cross-concordance? Results show a high magnitude of spousal concordance for substance use disorders with a third of the substance probands' spouses also substance dependent. In contrast, there was no spousal concordance for anxiety disorders. Couples were also concordant for having "no disorders." Both substance use and anxiety disorder concordance were associated with poorer global functioning and persistent illness. Assortative mating is a likely mechanism for spousal concordance given the elevated rate of substance use disorders among the relatives of spouses' of substance probands. Implications for family/genetic studies and the transmission of substance use disorders and "no disorders" include: (1) at the individual level, spousal concordance influences probands' course of illness, couples' marital functioning, and offspring's genetic and environmental context; and (2) at the population level, it shifts the general distribution of substance use disorders and "no disorders" by reducing the "average" couple concordance and increasing the number concordant and discordant couples at extremes of the distribution.

Evidence of an association between the vasopressin V1b receptor gene (AVPR1B) and childhood-onset mood disorders

CONTEXT

Disturbances in stress hormones have been implicated in mood disorders, in particular in the hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. Arginine vasopressin (AVP) plays a crucial role in modulating the HPA axis under stress and does so through a G protein-coupled receptor, vasopressin V1b receptor (AVPR1b).

OBJECTIVE

To determine if genetic variation in AVPR1B could be contributing to vulnerability to mood disorders.

DESIGN

We genotyped single nucleotide polymorphisms (SNPs) across the AVPR1B gene in a family-based sample with childhood-onset mood disorders. Six SNPs were genotyped; 2 were novel nonsynonymous polymorphisms, and the other 4 were constituents of a haplotype that was previously shown to be protective against depression.

SETTING

Twenty-three mental health facilities in Hungary.

PARTICIPANTS

The sample was composed of 382 Hungarian nuclear families ascertained through affected probands with a diagnosis of childhood-onset mood disorder.

MAIN OUTCOME MEASURES

Association with childhood-onset mood disorders was tested using the transmission disequilibrium test, which measures the transmission frequency of alleles, or haplotypes, from parents to affected offspring.

RESULTS

Two of the AVPR1B SNPs showed association individually (Lys65Asn: chi(2) = 7.81, P = .005; S4: chi(2) = 4.58, P = .03); of particular interest is Lys65Asn, which causes an amino acid change in an intracellular protein domain. Haplotype analysis demonstrated significant overtransmission of the most frequent haplotype (chi(2)(3) = 22.42, P <.001). Furthermore, stratifying the sample by sex established that the association was predominantly in affected females, which is consistent with previous observations.

CONCLUSIONS

We have found evidence to implicate the AVPR1B gene in the etiology of mood disorders, particularly in females. Antagonists of AVPR1b exhibit antidepressant qualities; hence, genetic variation in AVPR1B may have implications in HPA axis dysregulation in mood disorders.

Risk for premenstrual dysphoric disorder is associated with genetic variation in ESR1, the estrogen receptor alpha gene

BACKGROUND

Premenstrual dysphoric disorder (PMDD) is a heritable mood disorder that is triggered by gonadal steroids during the luteal phase in susceptible women.

METHODS

We performed haplotype analyses of estrogen receptors alpha and beta (ESR1 and ESR2) in 91 women with prospectively confirmed PMDD and 56 control subjects to investigate possible sources of the genetic susceptibility to affective dysregulation induced by normal levels of gonadal steroids. We also examined associations with the valine (Val)158methionine (Met) single nucleotide polymorphism (SNP) of the gene for catechol-O-methyltransferase (COMT), an enzyme involved in estrogen metabolism and prefrontal cortical activation.

RESULTS

Four SNPs in intron 4 of ESR1 showed significantly different genotype and allele distributions between patients and control subjects. Significant case-control differences were seen in sliding-window analyses of two-, three-, and four-marker haplotypes but only in those haplotypes containing SNPs in intron 4 that were positive in the single-locus analysis. No significant associations were observed with ESR2 or with the COMT Val158Met polymorphism, although the significant associations with ESR1 were observed only in those with the Val/Val genotype.

CONCLUSIONS

These are the first positive (albeit preliminary) genetic findings in this reproductive endocrine-related mood disorder and involve the receptor for a hormone that is pathogenically relevant.

d-Amino acid oxidase (DAO) genotype and mood symptomatology in schizophrenia

A series of genetic studies have identified the D-amino acid oxidase (DAO) gene as potentially contributing to schizophrenia susceptibility. An interacting gene, D-amino acid oxidase activator (DAOA) has also been implicated and it has been suggested that variation at these genes may influence the efficiency of glutamate gating at N-methyl-D-aspartate-type (NMDA) receptors. However, recent data suggests that DAOA may influence susceptibility to mood episodes across the spectrum of psychotic disorders rather than contributing to a specific psychosis phenotype. The aim of this study was to determine whether risk variation at DAO is similarly associated with affective or other clinical symptoms in psychosis. We have previously reported association between risk variation at DAO and schizophrenia in an Irish case-control sample. In this study we investigated the relationship between a defined genetic risk variant at DAO and PANSS-derived clinical symptom factors in a sample of 249 patients using principal component and Kruskal-Wallis analyses. Carriers of the DAO risk variant scored significantly higher on the 'depression/anxiety' factor than non-carriers (H=9.02, d.f.=2, p=0.01). These data suggest a potential role for DAO in susceptibility to depressive symptoms in schizophrenia, but a more general role for DAO in affective disorders cannot be excluded.