No evidence for physical anhedonia as a candidate symptom or an endophenotype in bipolar affective disorder.

OBJECTIVES: Bipolar affective disorder (BPAD) is clinically and genetically heterogeneous and the affected phenotype is poorly defined, hampering studies of its genetic basis. Studies of specific, familial, clinical indicators of BPAD may be useful for identifying heritable forms. Homogeneous forms of the disease may be identified in patients (candidate symptom approach) and some vulnerability markers may be sought in unaffected relatives of patients (intermediate traits or endophenotypes). Physical anhedonia (PA) is considered a possible candidate symptom and endophenotype in schizophrenia, but has never been specifically investigated in BPAD. METHODS: Physical anhedonia scores (measured using Chapman's Physical Anhedonia Scale) were compared in 351 euthymic bipolar patients, 130 of their first-degree relatives and 170 healthy controls with no personal or familial history of schizophrenia, mood disorders or suicidal behavior. We investigated intrafamilial resemblance of PA and compared the progressive and clinical characteristics of hedonic and anhedonic bipolar probands. RESULTS: Physical anhedonia was a stable trait in normothymic bipolar patients and significant intrafamilial correlation of PA scores was observed in bipolar families. However, PA scores were similar in unaffected relatives and controls and the clinical characteristics of anhedonic and hedonic patients did not differ significantly. Physical anhedonia was not associated with an increased familial risk for bipolar disorder. CONCLUSIONS: Physical anhedonia is a stable, familial dimension in BPAD families. It cannot be considered an endophenotype because unaffected relatives of bipolar patients and healthy controls have similar PA scores. It also cannot be considered a candidate symptom because it does not identify a homogeneous clinical and familial sub-group of bipolar patients. Given the results of previous studies, PA might be a specific candidate symptom (and endophenotype) to schizophrenia. However, the validation of this hypothesis requires replication studies in bipolar disorder and schizophrenia and further investigations in other psychiatric diseases (in particular across the mood disorder spectrum).

Bipolar patients with suicidal behavior: toward the identification of a clinical subgroup.

BACKGROUND: Suicide is the most severe and frequent complication of bipolar disorder, but little is known about the clinical characteristics of bipolar patients at risk of suicide. The purpose of this study was to identify those characteristics. METHOD: We studied 307 prospectively recruited DSM-IV-diagnosed bipolar I or II patients from November 1994 through October 2001. Semi-structured diagnostic interviews (the Diagnostic Interview for Genetic Studies and the Family Interview for Genetic Studies) were used to determine the diagnosis of bipolar disorder and its lifetime description, lifetime comorbid Axis I disorder diagnoses, familial history of psychiatric disorders and demographic characteristics. RESULTS: One hundred twenty-nine bipolar patients (42%) had made at least 1 suicide attempt in their life. Lifetime history of suicidal behavior was associated with history of suicidal behavior in first-degree relatives but not with a familial history of mood disorder. Early age at onset of mood disorder, total number of previous depressive episodes, alcohol and tobacco use, social phobia, antidepressant-induced mania, and personal history of head injury were associated with suicidal behavior. No association was observed with gender or diagnosis of bipolar I or II disorder. Social phobias, tobacco use, and personal history of head injury were no longer associated with suicidal behavior in the multivariate analysis. CONCLUSION: Bipolar patients with early age at bipolar disorder onset, high number of depressive episodes, personal history of antidepressant-induced mania, comorbid alcohol abuse, and suicidal behavior constitute a clinical subgroup at risk of suicidal behavior. This information, as well as familial history of suicide behavior, should improve suicide risk assessment in bipolar patients.

Lack of association between 5HT2A receptor gene haplotype, bipolar disorder and its clinical subtypes in a West European sample.

Bipolar affective disorder (BPAD) is a complex psychiatric disorder with a major genetic contribution. Abnormalities in serotonergic function have been implicated in its aetiology. The 5HT2A receptor (5HT2AR) gene is a strong candidate gene for involvement in BPAD, but previous association studies have reported conflicting results. These data are difficult to interpret because most negative results were obtained with small samples. The aim of this study was to test the association between the 5HT2AR gene and BPAD in a large West European sample. We studied the -1438G/A and the His452Tyr polymorphisms, for haplotype analysis to increase both informativity and the likelihood of detecting an association between BPAD and the 5HT2AR gene. We analysed the genotype, allele and haplotype distributions of two 5HT2AR gene variants in a population of 356 BPAD patients, which we compared with 208 healthy controls. We also carried out exploratory analysis in clinical subgroups of patients defined according to personal history of mood disorders, suicidal behaviour, comorbid psychiatric disorders and family history of affective disorders. We found no difference between BPAD patients and controls for allele, genotype and haplotype distributions. Exploratory analysis in subgroups of BPAD patients showed only a marginal difference in haplotype distribution between controls and BPAD patients with antidepressant-induced mania (P = 0.018). This difference was not significant after correction for multiple testing. Our study suggests that the 5HT2AR gene is unlikely to be involved in genetic susceptibility to BPAD but should be further investigated in a pharmacogenetic study.