Stressful life events and affective illness

OBJECTIVE

To investigate the association between the occurrence of affective illnesses and the number/type of experienced negative stressful life events in a twin material. A case-control study with an unrelated twin as control to the case and a co-twin control study were both undertaken with the same material.

METHOD

Postal questionnaire responses were used for confirming diagnosis and to inventory stressful life events. Risk ratios (RR) for groups of events were calculated using conditional logistic regression.

RESULTS

A dose-response relationship was observed for the association between stressful life events and affective illness. The RRs for specific groups of exposures were higher in the co-twin control study and higher for dizygotic twin pairs than for monozygotic twin pairs.

CONCLUSION

Individuals with a history of affective illness select themselves into high-risk environments, in part due to their genetic propensity to the disease. Thus, the association represents a classic genotype-environment correlation.

Psychological complexity: barriers to its integration into the neurobiology of major psychiatric disorders

In the authors' experience interactions between clinical and laboratory research have been greatly mutually facilitatory in the understanding and development of new treatments for the major mental illnesses. Examples in the literature are also highlighted to show how cross-disciplinary studies are important in understanding the subtle interactions of genetic and environmental mechanisms in psychiatric illness. Yet, the results of some current science policies encouraging project focus and superspecialization can lead to the separation of clinical and basic investigators, which threatens the integration of psychological complexity into the neurobiology of psychiatry at both a molecular and behavioral level. This paper endorses renewed effort toward the multidisciplinary team approach under the leadership of a physician-scientist in order to better integrate many fields of study critical to ameliorating the effects of psychiatric illness.

Family study of affective spectrum disorder

BACKGROUND

Affective spectrum disorder (ASD) represents a group of psychiatric and medical conditions, each known to respond to several chemical families of antidepressant medications and hence possibly linked by common heritable abnormalities. Forms of ASD include major depressive disorder (MDD), attention-deficit/hyperactivity disorder, bulimia nervosa, cataplexy, dysthymic disorder, fibromyalgia, generalized anxiety disorder, irritable bowel syndrome, migraine, obsessive-compulsive disorder, panic disorder, posttraumatic stress disorder, premenstrual dysphoric disorder, and social phobia. Two predictions of the ASD hypothesis were tested: that ASD, taken as a single entity, would aggregate in families and that MDD would coaggregate with other forms of ASD in families.

METHODS

Probands with and without MDD, together with their first-degree relatives, were interviewed using the Structured Clinical Interview for DSM-IV and a supplemental interview for other forms of ASD. The familial aggregation and coaggregation of disorders were analyzed using proband predictive logistic regression models, including a novel bivariate model for the presence or absence of each of 2 disorders in a relative as predicted by the presence or absence of each of 2 disorders in the associated proband.

RESULTS

In the 178 interviewed relatives of 64 probands with MDD and 152 relatives of 58 probands without MDD, the estimated odds ratio (95% confidence interval) for the familial aggregation of ASD as a whole was 2.5 (1.4-4.3; P =.001) and for the familial coaggregation of MDD with at least one other form of ASD was 1.9 (1.1-3.2; P =.02).

CONCLUSIONS

Affective spectrum disorder aggregates strongly in families, and MDD displays a significant familial coaggregation with other forms of ASD, taken collectively. These results suggest that forms of ASD may share heritable pathophysiologic features.

The serotonin transporter intronic VNTR enhancer correlated with a predisposition to affective disorders has distinct regulatory elements within the domain based on the primary DNA sequence of the repeat unit

We have demonstrated that a variable number tandem repeat domain (VNTR) within intron 2 of the serotonin transporter gene is a transcriptional regulatory domain which is potentially correlated with a predisposition to affective disorders and other behavioural conditions. This correlation based on copy number of the VNTR alone (nine, 10 or 12 copies of 16/17 base-pair element) has been controversial and not reproduced in all studies. We demonstrate that individual repeat elements within the VNTR domain differ in their enhancer activity in an embryonic stem cell model. This has implications for both the mechanism by which these VNTRs are correlated with the progression of the disease and suggests that clinical analysis should now be extended to correlate sequence variation within the VNTR with the disorder. The latter may resolve some of the conflicting data published to date.

Molecular genetics in the analysis of suicide

Each year, one million people die of suicide. Among the different identified risk factors, genetic factors seem to be part of a multidimensional behavior, including psychiatric, psychosocial, biological factors and physical illness. Family studies have provided evidence for familial transmission in suicide, confirmed in twin and adoption studies. At a molecular level, serotonin seems to be one of the key neurotransmitters implicated in suicidal behavior. Therefore, genes coding for proteins involved in serotonergic neurotransmission have been extensively studied in case-control association studies on suicide. Major findings concern Tryptophan hydroxylase (TPH) gene, particularly in violent suicidal behavior. Though they may seem contradictory, studies on Serotonin transporter (5-HTT), Monaomine oxidase (MAOA), Serotonin 2A and 2C receptors (5-HT2A and 5-HT2C) and Tyrosine hydroxylase (TH) genes are promising. In spite of those observations having some limitations, it appears that genetic factors are a serious risk factor, besides environmental aspects of suicidal behavior.

DSM-IV mania symptoms in a prepubertal and early adolescent bipolar disorder phenotype compared to attention-deficit hyperactive and normal controls

OBJECTIVE

To compare the prevalence of Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) mania symptoms in a prepubertal and early adolescent bipolar disorder phenotype (PEA-BP) to those with attention deficit hyperactivity disorder (ADHD) and normal community controls (CC).

METHODS

To optimize generalizeability, subjects with PEA-BP and ADHD were consecutively ascertained from outpatient pediatric and psychiatric sites, and CC subjects were obtained from a random survey. All 268 subjects (93 with PEA-BP, 81 with ADHD, and 94 CC) received comprehensive, blind, baseline research assessments of mothers about their children and of children about themselves. PEA-BP was defined by DSM-IV mania with elation and/or grandiosity as one criterion to ensure that subjects had one of the two cardinal symptoms of mania and to avoid diagnosing mania only by criteria that overlapped with those for ADHD.

RESULTS

Five symptoms (i.e., elation, grandiosity, flight of ideas/racing thoughts, decreased need for sleep, and hypersexuality) provided the best discrimination of PEA-BP subjects from ADHD and CC controls. These five symptoms are also mania-specific in DSM-IV (i.e., they do not overlap with DSM-IV symptoms for ADHD). Irritability, hyperactivity, accelerated speech, and distractibility were very frequent in both PEA-BP and ADHD groups and therefore were not useful for differential diagnosis. Concurrent elation and irritability occurred in 87.1% of subjects with PEA-BP. Data on suicidality, psychosis, mixed mania, and continuous rapid cycling were also provided.

CONCLUSION

Unlike late teenage/adult onset bipolar disorder, even subjects with PEA-BP selected for DSM-IV mania with cardinal symptoms have high rates of comorbid DSM-IV ADHD. High rates of concurrent elation and irritability were similar to those in adult mania.

Dimensional diagnosis of depression: adding the dimension of course to severity, and comparison to the DSM

It has long been debated whether depression is best classified with a categorical or dimensional diagnostic system. There has been surprisingly little discussion, however, of what the contents of a dimensional classification should include, with most studies employing a single dimension based on symptom severity. The present study explored whether a dimension based on prior course of depression increases the validity of a dimensional model based on symptom severity alone and whether the two dimensions combined improve upon the present categorical system (DSM). The sample consisted of 133 patients with a broad spectrum of depressive diagnoses. External validators included family history of mood disorder, assessed using the family history method, and course over a 6-month prospective follow-up period. Prior course contributed significant incremental validity over and above symptom severity in predicting subsequent course and family history of mood disorder. However, the linear combination of symptom severity and prior course provided only a minimal increase in predictive power over and above the DSM diagnoses of major depressive disorder (MDD) and dysthymia.

Wisconsin Twin Panel

The Wisconsin Twin Panel was initiated in 1994 to serve a study of the development of childhood mood and behavioral disorders. Families who give birth to twins within the state of Wisconsin are recruited within 6 months of the birth. The panel currently supports three ongoing, longitudinal research projects. Research foci include studying epigenetic contributions to emotional, physical, cognitive, and motoric development of infant and toddler twins; physiological concomitants of childhood temperament; and early risk and resiliency factors related to child psychopathology. All three studies include videotaped observational assessments and biological measures.

The dichotomy of schizophrenia and affective disorders in extended pedigrees

The paper reports the first controlled family study investigating not only 1st but also 2nd and 3rd degree relatives of patients with schizophrenia by direct diagnostic interviews. Regardless of their degree of relationship, all biological relatives of the patients were found to be at an elevated risk of schizophrenia (5.0% in 1st, 3.1% in 2nd, 1.5% in 3rd degree relatives compared to 0.8% among controls). Schizoaffective and affective disorders have also been found to be more common in the three groups of relatives but without a monotone decline of prevalence rates across the groups. Other psychiatric disorders were not found to be at an elevated risk in relatives of patients compared to controls. Thus, our findings support the hypothesis that psychotic, as well as affective disorders, aggregate in families of individuals with schizophrenia.However, in our study, the risk of schizophrenia and the risk of affective disorders correlated. Particularly, the magnitude of the risk of schizophrenia among relatives of probands with schizophrenia varied with the occurrence of affective disorders in relatives. In relatives, the risk of schizophrenia was maximal in absence of a family history of affective disorder. This constellation holds true even if only families of index cases without any affective syndrome during lifetime are considered.

[Molecular genetics of mood disorders]

Mood disorders are common diseases and cause a big burden on society, including suicide. Because there are many treatment resistant cases in mood disorders, it is very important to elucidate the pathophysiology of this condition to establish its prevention and its treatment. Genetic epidemiological studies have shown that genetic factors have an important role in the pathophysiology of mood disorders; therefore the molecular genetics studies of this condition have been extensively performed, such as positional approach (i.e., linkage study) and candidate gene approach (i.e., association study). Linkage studies have shown some candidate locations that have been reproduced in two or more studies, such as 1q21-42, 4p16, 10q21-26, 11p15, 12q23-24, 13q11-32, 18p11, 18q21-22, 22q11-13, Xp11, and Xq24-28. Most association studies have until now focused on the neurotransmitter system as a candidate molecule including serotonin transporter, serotonin receptors, dopamine receptors, tyrosine hydroxylase, MAO-A, COMT, and tryptophan hydroxylase. Moreover, phamacogenetic studies also have been carried out in this field to develop new drugs as well as personalized medicine. Future molecular genetic studies will find out the mood-disorder susceptible genes and open the gate to true treatment and prevention of this disorder as the Human Genome Project attains its goal.

Future of genetics of mood disorders research

This report summarizes the deliberations of a panel with representation from diverse disciplines of relevance to the genetics of mood disorders. The major charge to the panel was to develop a strategic plan to employ the tools of genetics to advance the understanding, treatment, and outcomes for mood disorders. A comprehensive review of the evidence for the role of genetic factors in the etiology of mood disorders was conducted, and the chief impediments for progress in gene identification were identified. The National Institute of Mental Health (NIMH) portfolios in the Genetics Research Branch and the Division of Mental Disorders, Behavioral Sciences, AIDS, and all genetics training activities were reviewed. Despite some promising leads, there are still no confirmed linkage findings for mood disorders. Impediments to gene finding include the lack of phenotypic validity, variation in ascertainment sources and methodology across studies, and genetic complexity. With respect to linkage, the committee recommended that a large-scale, integrated effort be undertaken to examine existing data from linkage and association studies of bipolar disorders using identical phenotypes and statistical methods across studies to determine whether the suggestive linkage findings at some loci can be confirmed. Confirmation would justify more intensive approaches to gene finding. The committee recommended that the NIMH support continued efforts to identify the most heritable subtypes and endophenotypes of major depression using the tools of genetic epidemiology, neuroscience, and behavioral science. The field of genetic epidemiology was identified as an important future direction because population-based, epidemiologic studies of families and unrelated affected individuals assume increasing importance for common chronic diseases. To prepare for shifts to more complex genetic models, the committee recommended that the NIMH develop new interdisciplinary training strategies to prepare for the next generation of genetics research.

Preclinical models: status of basic research in depression

Approximately one half-century ago several classes of medications, discovered by serendipity, were introduced for the treatment of depression and bipolar disorder. These highly effective medications revolutionized our approach to mood disorders and helped launch the modern era of psychiatry. Yet our progress since those serendipitous discoveries has been disappointing. We still do not understand with certainty how those medications produce their desired clinical effects. We have not introduced newer medications with fundamentally different mechanisms of action than the older agents. We have not identified the genetic and neurobiological mechanisms underlying depression and mania, nor do we understand the mechanisms by which nongenetic factors influence these disorders. We have only a rudimentary understanding of the circuits in the brain responsible for the normal regulation of mood and affect, and of those circuits that function abnormally in mood disorders. In approaching these gaps in our knowledge, this workgroup highlighted four major areas for future investment. These include developing better animal models of mood disorders; identifying genetic determinants of normal and abnormal mood in humans and animals; discovering novel targets and biomarkers of mood disorders and treatments; and increasing the recruitment of investigators from diverse backgrounds to mood disorders research.

Synaptic plasticity and mood disorders

Recent studies demonstrate that the molecular elements known to regulate neuronal plasticity in models of learning and memory are also involved in the actions of drugs used for the treatment of depression and bipolar disorder. This includes up-regulation of transcription factors, such as the cAMP response element binding protein and neurotrophic factors, such as brain derived neurotrophic factor. These findings raise the possibility that regulation of neural plasticity in specific neuronal circuits is integrally involved in the therapeutic intervention of mood disorders. Atypical antipsychotic drugs, including clozapine and olanzapine, are also effective for the treatment of bipolar disorder, and are used as add-on medication for unipolar depression. The possibility that these atypical antipsychotic drugs also influence the molecular determinants of synaptic plasticity that are involved in the response to drugs used for the treatment of mood disorders, is discussed.

The Munich Vulnerability Study on Affective Disorders: stability of polysomnographic findings over time

BACKGROUND

Some of the sleep abnormalities found in depression also persist in remission, suggesting that these parameters could represent trait or vulnerability markers. In a previous study, we found that about one third of a group of high-risk probands (HRPs) showed sleep patterns that were comparable to those of depressed patients. In the present study, we re-investigated a subsample of these HRPs to evaluate the stability of these findings over time.

METHODS

We investigated the sleep-electroencephalograms of 82 healthy subjects with a high genetic load of affective disorders. We were able to re-investigate 26 of these HRPs after a mean interval of 3.5 years. Thirty-five unrelated control probands and 33 unrelated depressed inpatients that were recruited at the first investigation served as reference groups.

RESULTS

At index investigation, we found that the HRPs showed a significantly increased rapid eye movement (REM) sleep density compared to control subjects. At the second examination, no changes of the polysomnographic observations over time could be observed; in particular, the REM density remained elevated.

CONCLUSIONS

The increased REM density in high-risk subjects for an affective disorder at index investigation was stable over time, so that one of the requirements for a true vulnerability marker is fulfilled.

Do puerperal psychotic episodes identify a more familial subtype of bipolar disorder? Results of a family history study

Bipolar women have a marked vulnerability to puerperal psychosis, an episode of mania or psychosis following childbirth. We have conducted a family history study to examine the question of whether a vulnerability to puerperal episodes of illness is a marker for a more familial form of bipolar disorder. A consecutive series of 103 bipolar disorder probands were recruited in a lithium clinic and given a semi-structured interview, including a detailed family history. For the 52 female probands, information was also obtained about the relationship of episodes to childbirth. The morbid risk of affective disorder in first-degree relatives of bipolar women who had suffered an episode of mania, hypomania or schizoaffective mania with onset within 6 weeks of childbirth was significantly higher than that in relatives of parous bipolar women with no episodes in relation to childbirth (P = 0.0077). Despite relatively small numbers, this study provides evidence to support the hypothesis that puerperal episodes identify a more familial subtype of bipolar disorder.

Pharmacogenetics of antidepressant and mood-stabilizing drugs: a review of candidate-gene studies and future research directions

Heterogeneity of clinical response to antidepressant and mood-stabilizing drugs and susceptibility to adverse effects are major clinical problems. It is reasonable to suggest a genetic contribution to these inter-individual differences. Thus, pharmacogenetic approaches could provide the clinician with tools to individualize pharmacotherapy. In this paper, published reports that address the genetic basis of response to antidepressant drugs and mood-stabilizing drugs are selectively reviewed. There is substantial support for the assumption that genetic factors play a role in response to lithium and a degree of support for a role of such factors in response to antidepressants. Based on a Medline search and access to papers accepted but not yet published, studies on the role of specific candidate genes are comprehensively evaluated. A number of studies from different groups point to a role for polymorphism of the serotonin transporter gene in the therapeutic response to specific serotonin reuptake inhibitors. There are reports of other candidate genes, particularly in the serotonergic system, but these have still to be replicated. There is little evidence thus far that points to a role for specific candidate genes in response to mood-stabilizing drugs. Future research directions including the selection of relevant candidate genes, pivotal issues in the design of studies and high throughput methods of analysis are discussed in the light of the findings. Although pharmacogenetic approaches have great potential in the treatment of major depression and bipolar disorder, substantial further research is needed. Careful attention needs to be paid to research design issues and potential confounding factors such as population stratification. High throughput, genome-wide approaches could greatly accelerate the acquisition of relevant data but their success is dependent on the availability of appropriate clinical samples.

Familial pathways to early-onset suicide attempt: risk for suicidal behavior in offspring of mood-disordered suicide attempters

BACKGROUND

Although adoption, twin, and family studies have shown that suicidal behavior is familial, the risk factors for familial transmission from parent to child remain unclear.

METHODS

A high-risk family study was conducted comparing the offspring of 2 mood-disordered groups: suicide attempters and nonattempters. Recruited from 2 sites, probands were 81 attempters and 55 nonattempters, with 183 and 116 offspring, respectively. Offspring were assessed by investigators masked to proband status. Probands and offspring were assessed with respect to psychopathologic findings, suicide attempt history, impulsive aggression, and exposure to familial environmental stressors.

RESULTS

Offspring of attempters had a 6-fold increased risk of suicide attempts relative to offspring of nonattempters. Familial transmission of suicide attempt was more likely if (1) probands had a history of sexual abuse and (2) offspring were female and had a mood disorder, substance abuse disorder, increased impulsive aggression, and a history of sexual abuse.

CONCLUSIONS

The offspring of mood-disordered suicide attempters are at markedly increased risk for suicide attempts themselves. Familial transmission of suicidal behavior in families with mood disorders almost always requires transmission of a mood disorder and is also related to the offspring's impulsive aggression and the familial transmission of sexual abuse. Early treatment of mood disorders and targeting impulsive aggression and sexual trauma may be helpful in the prevention and treatment of suicidal behavior in families with mood disorders.

The silencer activity of the novel human serotonin transporter linked polymorphic regions

Enhancer/silencer activity of each allelic variant of the human serotonin transporter linked polymorphic region (5-HTTLPR) including newly found ones was measured in several cell lines including raphe-nucleus-derived RN46A. 5-HTTLR variants ligated in pGL-3 promoter vector increased luciferase activity in COS-7 cells and PC12 cells, where no significant differences among the variants were observed. In RN46 cell lines, however, 5-HTTLPRs decreased luciferase activity to 80-30%, acting as silencers not as enhancers. Some allelic variants (15, 19, 20 and 22) showed even significantly stronger silencer activities than others in RN46A. We also examined relationship between allelic frequencies, the enhancer/silencer activities and incidents of mood disorder. The categorized genotypic or allelic frequencies was not significantly different between the mood disorder and the control. No significant difference was detected either when analyzed by silencer activities of each allelic variant.

Association study of the short tandem repeat in the 5' upstream region of the cholecystokinin gene with mood disorders in the Japanese population

We have recently identified a novel polymorphic short tandem repeat (STR) in the 5' upstream region of the cholecystokinin (CCK) gene and reported its association with panic disorder. A linkage study of affective disorder showed a modest linkage signal on the short arm of chromosome 3, the location of the CCK gene. Furthermore, clinical comorbidity of depression and anxiety disorders have been documented. In the present study, we examined a possible association of the CCK STR with mood disorders. We genotyped 165 subjects with mood disorders consisting of unipolar and bipolar disorders and 253 control samples. However, no significant allelic associations were detected between the STR and either the combined mood disorders (P = 0.885), the unipolar group (P = 0.296), or the bipolar group (P = 0.605). These data suggest that the CCK promoter STR is unlikely to have a major genetic effect on the development of mood disorders in the Japanese population.

Toward molecular diagnostics of mood disorders in psychiatry

Mental disorders are highly prevalent and often difficult to diagnose. There is a significant gap between advances in their pharmacotherapy and the present lack of objective biologic tests for diagnosis. The special complexity of diagnosis in psychiatry is related to the absence of objective diagnostic "gold standards", co-morbidity, heterogeneity and equifinality, quantitative trait loci, and locus heterogeneity. Here, we review recent findings relating to diagnostic, pathophysiological, and linkage markers for mood disorders at the biochemical level involving monoamine neurotransmitters, hormones, and signal-transducing G proteins. Identification of biological diagnostic markers could enable segregating mood disorders to several biologically different subtypes. New-era methods and strategies involving genomics, proteomics, multi-marker approach and single nucleotide polymorphisms have the potential to revolutionize future diagnosis in psychiatry.

Pharmacogenetics of lithium prophylaxis in mood disorders: analysis of COMT, MAO-A, and Gbeta3 variants

We studied the possible association between the prophylactic efficacy of lithium in mood disorders and the following gene variants: catechol-O-methyltransferase (COMT) G158A, monoamine oxydase A (MAO-A) 30-bp repeat, G-protein beta 3-subunit (Gbeta3) C825T. A total of 201 subjects affected by bipolar (n = 160) and major depressive (n = 41) disorder were followed prospectively for an average of 59.8 months and were typed for their gene variants using PCR techniques. COMT, MAO-A, and Gbeta3 variants were not associated with lithium outcome, even when possible stratification effects such as sex, polarity, age at onset, duration of lithium treatment, and previous episodes were included in the model. The pathways influenced by those variants are not therefore involved with long-term lithium outcome in our sample.

Family-based association study of 5-HTTLPR, TPH, MAO-A, and DRD4 polymorphisms in mood disorders

Variants of the functional polymorphism in the serotonin transporter (upstream regulatory region: 5-HTTLPR), the tryptophan hydroxylase (TPH), the monoamine oxidase A (MAO-A), and the dopamine receptor D4 (DRD4) genes have all been associated with mood disorders. The aim of this study was to test those hypotheses by using a family-based association approach. Both diagnoses and psychopathology were used for phenotype definitions. A total of 134 nuclear families with mood disorders, with probands affected by bipolar (n = 103) or major depressive (n = 58) disorders, were included in the study. All subjects were typed for the above-mentioned gene variants using polymerase chain reaction (PCR) technique. No significant transmission disequilibrium was found in the overall sample for any polymorphism. A separate analysis of bipolar subjects only, or the use of continuous psychopathologic traits as affectation status did not influence the observed results. Our study did not support the involvement of 5-HTTLPR, TPH, MAO-A, or DRD4 polymorphisms in mood disorders.