Bipolar disorders and affective temperaments: a national family study testing the "endophenotype" and "subaffective" theses using the TEMPS-A Buenos Aires.

Background: The purpose of this study is to examine the prevalence of affective temperaments between clinically unaffected relatives of bipolar patients and secondarily to investigate the impact of these "subaffective" forms on their quality of life (QoL).

Methods: The study was performed in seven sites across Argentina. We administered the scales TEMPS-A and Quality of Life Index to a sample of 114 non-ill first degree relatives of bipolar disorder patients ("cases") and 115 comparison subjects without family history of affective illness ("controls"). We used The Mood Disorder Questionnaire to rule out clinical bipolarity.

Results: Mean scores on all TEMPS-A subscales were significantly higher in cases, except for hyperthymia. The prevalence of affective temperaments, according to Argentinean cut-off points, was also higher, with statistical significance for cyclothymic and anxious temperaments. Regarding QoL, we found no significant differences between both groups, except for interpersonal functioning, which was better in controls. A detailed subanalysis showed significant effects of QoL domains for all temperaments, except for the hyperthymic.

Limitations: We used self-report measures. A larger sample size would have provided us greater statistical power for certain analyses.

Conclusions: Our findings support the concept of a spectrum of subthreshold affective traits or temperaments - especially for the cyclothymic and anxious - in bipolar pedigrees. We further demonstrated that, except for the hyperthymic, quality of life was affected by these temperaments in "clinically well" relatives. Overall, our data are compatible with the "endophenotype" and "subaffective" theses for affective temperaments.