Quality of life in unaffected twins discordant for affective disorder

BACKGROUND: The disability and hardship associated with affective disorder is shared by the family members of affective patients and might affect the family member's quality of life.

METHOD: In a cross-sectional, high-risk, case-control study, monozygotic (MZ) and dizygotic (DZ) twins with (High-Risk twins) and without (the control group/Low-Risk twins) a co-twin history of affective disorder were identified through nationwide registers. The aim of the present study was to investigate the hypothesis that a genetic liability to affective disorder is associated with a lower perception of quality of life.

RESULTS: Univariate analyses showed that quality of life in all domains was impaired for the 121 High-Risk twins compared to the 84 Low-Risk twins. In multiple regression analyses, the differences remained significant after adjustment for sex, age, marital status and years of education. Adjusted for the effect of subclinical anxiety and depressive symptoms, the differences were significant on the domain environment and total WHOQoL-BREF and marginally significant on the domain physical health and overall quality of life.

LIMITATIONS: It is not possible from the cross-sectional analyses to distinguish between subsyndromal state and trait scores.

CONCLUSIONS: Perceived health related quality of life might share common familial vulnerability with affective disorders. Having a co-twin with affective disorder seem to have a negative influence on quality of life of the healthy co-twin and this influence might be due to the genetic liability to affective disorder. These findings need to be replicated in future family studies.