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.

Association study of MAO-A, COMT, 5-HT2A, DRD2, and DRD4 polymorphisms with illness time course in mood disorders

The aim of our study was to investigate a possible influence of monoamine oxydase A (MAO-A), catechol-O-methyltransferase (COMT), serotonin receptor 2A (5-HT2A), dopamine receptor D2 (DRD2), and dopamine receptor D4 (DRD4) gene variants on timing of recurrence in mood disorders. Gene variants were determined using PCR-based techniques in 550 inpatients affected by recurrent mood disorders (major depressives: n = 212; bipolars: n = 338), rapid cycling mood disorder (n = 81), and 663 controls. We investigated possible genetic influences by comparing illness time course of subjects subdivided according to genotype using multivariate analysis of variance (MANOVA). We could not observe a significantly different time course. No demographic and clinical variables such as sex, age or polarity of onset, presence of psychotic features, genetic loading, or education level influenced the observed results. Our results suggest that MAO-A, COMT, 5-HT2A, DRD2, and DRD4 gene variants are not involved in susceptibility toward different time courses in mood disorders.

Association of 5-HT(2A) receptor gene polymorphism with major affective disorders: the case of a subgroup of bipolar disorder with low suicide risk

BACKGROUND

The implication of serotonin in suicide and affective disease explains why the 5-HT(2A) receptor gene has been proposed as a candidate gene in these disorders, although with conflicting results.

METHODS

We analysed the distribution of the 5-HT(2A)-1438A/G genetic polymorphism in 192 patients with major affective disorder (127 bipolar disorders and 65 unipolar disorders) compared to 142 healthy control subjects.

RESULTS

We found a higher frequency of the A allele in affected patients than in control subjects (p =.034), this difference being particularly striking for the subgroup of patients with type I bipolar disorder (p =.015). Patients with no personal and/or familial history of suicide attempts mainly accounted for the excess of the A allele in affected patients.

CONCLUSIONS

The association detected in this study suggests that the 5-HT(2A) receptor gene may play a role in the genetic susceptibility to bipolar disorder, through a specific subgroup of bipolar type I patients with lower risk of suicidal behavior.

Serotonin transporter gene associated with lithium prophylaxis in mood disorders

The aim of this study was to investigate the possible association between the functional polymorphism in the upstream regulatory region of the serotonin transporter gene (5-HTTLPR) and the prophylactic efficacy of lithium in mood disorders. Two hundred and one subjects affected by bipolar (n = 167) and major depressive (n = 34) disorder were followed prospectively for an average of 58.2 months and were typed for their 5-HTTLPR variant using polymerase chain reaction techniques. 5-HTTLPR variants were associated with lithium outcome (F = 5.35; df = 2,198; P = 0.005). Subjects with the s/s variant showed a worse response compared to both l/s and l/l variants. Consideration of possible stratification effects such as sex, polarity, age at onset, duration of lithium treatment and previous episodes did not influence the observed association. 5-HTTLPR variants may be a possible influencing factor for the prophylactic efficacy of lithium in mood disorders.

Angiotensin converting enzyme gene insertion/deletion polymorphism: case-control association studies in schizophrenia, major affective disorder, and tardive dyskinesia and a family-based association study in schizophrenia

Angiotensin converting enzyme (ACE) is a candidate gene for psychiatric disorders. We examined the frequency of a functional insertion/deletion (I/D) polymorphism in the 16th intron of the ACE gene (located on chromosome 17q23) in groups of patients with schizophrenia (n = 104 and 113), major depression (n = 55), and bipolar disorder (n = 87) compared to healthy control subjects (n = 87). There was no evidence for allelic or genotypic association of the polymorphism with any of the disorders or with tardive dyskinesia (TD) in patients with schizophrenia. In a sample of nuclear families (n = 61) made up of one or more patients with schizophrenia recruited with their parents, there was no evidence for biased transmission of ACE I/D alleles. Particularly in the case of schizophrenia, these findings do not support an association of the ACE I/D polymorphism with the phenotypes examined.

Genetic modification of corticosteroid receptor signalling: novel insights into pathophysiology and treatment strategies of human affective disorders

Every disturbance of the body, either real or imagined, evokes a stress response. Essential to this stress response is the activation of the hypothalamic-pituitary-adrenocortical (HPA) system, finally resulting in the release of glucocorticoid hormones from the adrenal cortex. Glucocorticoid hormones, in turn, feed back to this system by central activation of two types of corticosteroid receptors: the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR) which markedly differ in their neuroanatomical distribution and ligand affinity. Whereas a brief period of controllable stress, experienced with general arousal and excitement, can be a challenge and might thus be beneficial, chronically elevated levels of circulating corticosteroids are believed to enhance vulnerability to a variety of diseases, including affective disorders. Corticosteroids are known to influence emotions and cognitive processes, such as learning and memory. In addition, corticosteroids play extremely important roles in modulating fear and anxiety-related behaviour. The mechanisms by which corticosteroids exert their effects on behaviour are often indirect, by modulating particular sets of neurons or neurotransmitter systems. In addition, the timing of corticosteroid increase (before, during or after exposure to a stressor) determines whether and how behaviour is affected. The cumulative evidence makes a strong case implicating corticosteroid receptor dysfunction in the pathogenesis of affective disorders. Although definitive controlled trials remain to be conducted, there is evidence indicating that cortisol-lowering or corticosteroid receptor antagonist treatments may be of clinical benefit in selected individuals with major depression. A more detailed knowledge of the GR signalling pathways therefore opens up the possibility to specifically target GR function. In recent years, refined molecular technologies and the generation of genetically engineered mice (e.g. "conventional" and "conditional" knock-outs) have allowed to specifically target individual genes involved in corticosteroid receptor signalling and stress hormone regulation. Given the fundamental role of corticosteroid receptors in hippocampal integrity and mental performance during aging and psychiatric disorders, the identification and detailed characterization of these molecular pathways will ultimately lead to the development of novel neuropharmacological intervention strategies.

[Levels and molecular heterogeneity of serotonin transporter protein in platelets of patients with different mental diseases: a comparative analysis with the use of monoclonal and polyclonal antibodies]

Polyclonal (PAb) and monoclonal (MAb) antibodies to CT2-epitope of the C-terminal fragment of serotonin transporter (SERT) protein were used to study the levels and molecular heterogeneity of platelet SERT in healthy donors and patients with affective (AD) and somatoform (SD) disorders, schizoaffective disorder (SAD) and schizophrenia. SERT was found to exist as high molecular wight (HMW) and low molecular weight (LMW) forms separated after electrophoresis. The levels of HMW and LMW forms of SERT were significantly, decreased in mentally ill patients as compared to healthy individuals. Unlike PAb, horse radish peroxidase (HRP)-conjugated MAbs were more sensitive and specific to SERT and could detect the LMW form of SERT as a duplet protein form with MW about 40 and 43 kDa. The MAb to CT2 C-terminal fragment of SERT conjugated with HRP is considered to be a new valuable tool for further investigation of SERT expression, properties, and posttranslation modification in the controls and in patients with different psychopathology.

Pharmacogenetics in affective disorders

Pharmacogenetics will be of substantial help in the field of affective disorders pharmacotherapy. The possible definition of a genetic liability profile for drug side-effects and efficacy will be of great help in treatments that need weeks to months to be effective. During the last few years, a number of groups have reported possible liability genes. The efficacy and time of onset of selective serotonin reuptake inhibitors have been associated with a polymorphism in the promoter region of the transporter (SERTPR) in many independent studies, while variants at the tryptophan hydroxylase gene, 5-HT2a receptor and G-protein beta3 have been associated with them in pilot studies. Lithium long-term prophylactic efficacy has been associated with SERTPR, TPH and inositol polyphosphate 1-phosphatase variants, though in unreplicated samples. A number of further candidate genes were not associated with these treatments. In conclusion, both acute and long-term treatments appear to be, at least to some extent, under genetic influence and preliminary data have identified possible liability genes.

Genetic segregation analysis of recurrent, early-onset major depression: evidence for single major locus transmission

Coordinated efforts are now underway to identify susceptibility genes for unipolar major depressive disorder (MDD) and related disorders. These studies have focused on recurrent, early-onset MDD (RE-MDD), thought to be the most familial form of this disorder. The goal of this study was to conduct a complex segregation analysis of recurrent MDD and other major mood disorders aggregating in families identified by probands with RE-MDD. Eighty-one families were identified through probands over the age of 18 who met criteria for recurrent (> or =2 episodes), early-onset (< or =25 years), nonpsychotic, unipolar MDD (RE-MDD) and included 407 first-degree relatives and 835 extended relatives. Psychiatric diagnoses for probands and their family members who provided blood samples were formulated from structured personal interviews, structured family history assessments, and available medical records. The remaining family members who participated and those who were deceased were evaluated through the family history method augmented by available medical records. Best-estimate diagnoses were made during a consensus conference according to established diagnostic criteria. Segregation analyses were performed using the REGD routine in S.A.G.E. release 4.0. The segregation analysis of recurrent MDD supported a sex-independent Mendelian codominant model. Analysis of major mood disorders supported a sex-independent Mendelian dominant model. Interestingly, inclusion of spousal residual correlations provided better fitting models for recurrent MDD but not the broader phenotype of major mood disorders. Unlike unipolar MDD, the lifetime prevalence of bipolar I disorder in this sample of families did not exceed the reported population prevalence [Zubenko et al., 2001]. Our results suggest that a major locus contributes to the expression of recurrent MDD and possibly other major mood disorders within families identified by probands with RE-MDD. Due to the limitations of the segregation analysis model, our results cannot address whether the same major locus is segregating across families in our sample or whether multiple major loci are involved (genetic heterogeneity). The absence of aggregation of bipolar I disorder in these families strongly suggests that while the genetic determinants of unipolar and bipolar disorders may overlap, they are not identical. Our findings illustrate the advantage of employing families identified by probands with RE-MDD in studies designed to detect susceptibility loci for unipolar MDD and related disorders.

Serotonin transporter promoter genotype and illness recurrence in mood disorders

We tested the hypothesis that allelic variation of 5-HTT linked polymorphic region (5-HTTLPR) could influence illness onset and recurrence in 129 bipolar and 128 unipolar recurrent patients. Among bipolar patients, homozygotes for the short variant showed an earlier age at onset and a lower recurrence rate than heterozygotes and homozygotes for the long variant. Unipolar patients showed a trend toward the same difference. Data support a role for 5-HTTLPR in course of affective illness.

Premorbid psychiatric risk factors for postictal psychosis

Postictal psychosis (PIP) is a common and clinically significant sequela of inpatient epilepsy monitoring. A series of 622 patients with complex partial epilepsy undergoing video-EEG evaluations as candidates for epilepsy surgery were evaluated, by structured psychiatric interview, for individual and family psychiatric histories, depression, anxiety, and features of personality disorders. No patient had psychotic symptoms at baseline. Twenty-nine developed a PIP episode during monitoring. The a priori hypotheses were that patients with PIP would have higher baseline schizotypal and paranoid personality ratings and a greater prevalence of histories of psychiatric treatment and family history of psychotic illness. However, only a higher prevalence of mood disorder among first- and second-degree relatives distinguished the patients who developed PIP on logistic regression analyses (odds ratio=3.49, P=0.001). Possible mechanisms linking vulnerability toward mood disorders and the development of psychotic symptoms in epilepsy are discussed.

Mood congruent memory bias induced by tryptophan depletion

BACKGROUND

Mood congruent memory bias predicts a more superior recall memory of learnt material congruent with the mood state at the time of learning. The present study is the first report of an experimental study in which a biological mood induction was used to test this hypothesis. The influence of acute tryptophan (TRP) depletion, inducing low serotonin neurotransmission and a depression of mood, on memory bias was evaluated in healthy volunteers (16 with and 11 without a family history of major affective disorder).

METHODS

Twenty-seven subjects received 100 g of an amino acid mixture with and without TRP according to a placebo-controlled, double-blind, balanced, cross-over design. An affective memory test consisting of a 30-word list with words of positive, neutral, and negative affective valence and a mood questionnaire were assessed at 6 and 24 h following treatment administration.

RESULTS

TRP depletion impaired delayed recall of neutral and positive words, but not of negative words. There was no interaction of family history and treatment and there was no post hoc association between the influence of TRP-depletion on mood and on affective memory bias.

CONCLUSION

Experimentally induced serotonergic depletion in normal individuals shifts affective memory bias towards negative affective valent verbal stimuli.

Lithium long-term treatment in mood disorders: clinical and genetic predictors

Lithium is the most widely used long-term treatment for recurrent mood disorders. Despite its proven efficacy, patients show a variable response, ranging from complete efficacy to no influence at all. This paper reviews possible predictors of response focusing on molecular genetic studies. The functional polymorphism in the upstream regulatory region of the serotonin transporter gene (5-HTTLPR) has been associated with lithium long-term efficacy in two independent studies, marginal associations have been reported for tryptophan hydroxylase and inositol polyphosphate 1-phosphatase (INPP1). A number of other candidate genes and anonymous markers did not yield positive associations. Therefore, even though some positive results have been reported, no unequivocal susceptibility gene for lithium efficacy has been identified.

Malignancy of recurrent, early-onset major depression: a family study

Coordinated efforts to identify susceptibility genes for unipolar major depressive disorder (MDD) and related disorders are now underway. These studies have focused on recurrent, early-onset MDD (RE-MDD), the most heritable form of this disorder. The goal of this study was to characterize the burden of MDD and other mood disorders, comorbid mental disorders, and excess mortality in RE-MDD families. A total of 81 families were identified through probands over the age of 18, who met criteria for recurrent (> or = 2 episodes), early-onset (< or = 25 years), nonpsychotic, unipolar MDD (RE-MDD), and included 407 first-degree relatives and 835 extended relatives. Psychiatric diagnoses for probands and their family members who provided blood samples were formulated from structured personal interviews, structured family history assessments, and available medical records. The remaining family members who participated and those who were deceased were evaluated through the family history method augmented by available medical records. Best estimate diagnoses were made during a consensus conference according to established diagnostic criteria. Approximately half of the first-degree relatives and a quarter of extended relatives of RE-MDD probands suffered from at least one mood disorder, typically MDD. As commonly observed for other oligogenic, multifactorial disorders, the severity of MDD reflected by age at onset and number of episodes attenuated with increasing familial/genetic distance from the proband. A substantial fraction of RE-MDD probands and their first-degree relatives met diagnostic criteria for additional psychiatric disorders that include prominent disturbances of mood. The deceased relatives of RE-MDD probands died at a median age that was 8 years earlier than for the local population; over 40% died before reaching age 65. These differences in mortality statistics resulted from a shift toward younger ages at death across the lifespan, including a fivefold increase in the proportion of individuals who died in the first year of life. Several-fold increases in the proportion of deaths by suicide, homicide, and liver disease were observed among the relatives of RE-MDD probands. However, the rank order of the three most common causes of death-heart disease, cancer, and stroke-remained unchanged and differences in the proportions of deaths from the remaining causes were small. RE-MDD is a strongly familial condition with a high rate of psychiatric comorbidity, whose malignant effects have a significant negative impact on the health and longevity of patients and their family members.

Association study between cannabinoid receptor gene (CNR1) and pathogenesis and psychotic symptoms of mood disorders

Cannabis can induce mood change and sometimes psychotic symptoms in normal persons. In brain, the main active ingredient of cannabis acts via the cannabinoid CB1 receptor (CNR1) which is located on chromosome 6q14-15. Linkage studies have suggested the presence of a bipolar disorder susceptibility locus on chromosome 6q. In this population based association study, we tested the hypothesis that a microsatellite polymorphism in the promoter region of the CNR1 gene confers susceptibility to mood disorders and psychotic features. We genotyped the CNR1 gene is 154 mood disorder patients and 165 normal controls. The results showed that the triplet repeat polymorphism in the promoter region of the CNR1 gene was not likely to be involved in the pathogenesis or in the psychotic symptoms of mood disorders.

Combining genetic and genomic approaches to study mood disorders

Recent technological advances in genetic manipulations and DNA microarrays are profoundly altering the landscape of biological research, offering opportunities to investigate biological questions that were only dreamed of a few years ago. With this revolution comes the hope of being able to tackle some of the more arduous challenges that the central nervous system has presented to the research community. Specifically, a major goal in the study of neuropsychiatric disorders has been to identify underlying mechanisms of brain dysfunction with the expectation that these insights may allow a better diagnosis, prevention and effective treatments for these disorders. For the most part, treatments of these disorders have relied on serendipitous discovery of pharmacological entities with therapeutic efficacy, while the causes of the disorders have remained unknown. The serotonin system, and the serotonin(1A) (5-HT(1A)) receptor in particular, have been under intense investigation, mostly due to the fact that serotonergic drugs that directly or indirectly affect the 5-HT(1A) receptor, are effective therapeutic agents in treating patients with various neuropsychiatric disorders, including anxiety and depression. Genetic deletion of the receptor in mouse results in increased anxiety, thus supporting an active role for this receptor in mood regulation. However, the analysis of genetic deletion experiments can be confounded by hidden developmental roles of the missing receptor, by adaptive compensatory mechanisms, as well by the fact that the genes or gene products that are responsible for the cellular and molecular aspects of the phenotype may be several steps removed from the genetic intervention. Here, we present a combined methodological approach of tissue specific and conditional genetic manipulations, with large-scale search for altered gene expression, as an experimental framework to investigate the role of genes with complex functions and/or complex expression patterns. The 5-HT(1A) receptor is used as a model of gene product with complex functions and distributions, and as a prototypical system to which these new genetic approaches are currently being applied.

Genetics of affective disorders

Despite substantial evidence for heritability in affective disorders the contributing genes have proven elusive. Here we discuss the genetic epidemiology of depression, as well as methodological issues and results from molecular genetic studies. There has been rapid advances in genetics, genomics and statistical modelling, facilitating the search for molecular mechanisms underlying affective disorders and several strategies reviewed in this paper hold promise to provide progress in the field. Considering the poorly understood biological basis of vulnerability to affective disorders, the identification of genes involved in the pathophysiology will unravel mechanisms and pathways that could permit more personalized therapeutic strategies and result in new targets for pharmacological intervention.