An association between depressive mood and ischemic heart disease has been demonstrated that does not appear to be explained by early-life environmental and genetic factors. A study of 6714 twins who were Danish middle-aged and old was conducted among individuals from 2 large population-based twin cohorts, with the results published in Acta Psychiatrica Scandinavica.
The investigators sought to assess whether the risk for cardiovascular disease among persons with a mood disorder could be supported by shared genetic and early environmental influences. They used Cox proportional hazards regression to perform individual-level and intrapair studies of the relationship between self-reported depression symptomatology and register-based diagnoses of ischemic heart disease. Data from the Longitudinal Study on Aging Danish Twins (LSADT) and the Middle-Aged Danish Twins (MADT) study were included in the analysis.
Among the 6714 twins who were evaluated, a total of 2400 and 4314 individual twins were included from LSADT and MADT, respectively. Overall, 32.9% (2208 of 6714) of the twins studied were monozygotic twins. “The mean age was 65.8 years and 54.5% were women,” the authors wrote. During follow-up, 20% of the twins in LSADT and 13% of the twins in MADT were diagnosed with ischemic heart disease.
The results of the study showed that in the main twin population, participants with a depression score in the 2 highest tertiles had a 27% higher hazard ratio (HR) for ischemic heart disease compared with those with a score in the lowest tertile (95% CI, 1.07-1.51), after adjusting for all covariates. With respect to the affective and somatic symptom scores, participants with a score in the highest tertile likewise had a 25% (95% CI, 1.03-1.53) and a 35% (95% CI, 1.12-1.62) higher HR, respectively, for ischemic heart disease.
In addition, intrapair analyses of the 2300 complete twin pairs in the complete twin pair population demonstrated an association between all 3 types of depression symptomatology scores and ischemic heart disease, which was similar to the main findings of the study. Participants in the highest tertile of the total depression score had a 64% higher HR (95% CI, 0.97-2.76) for ischemic heart disease. The corresponding HRs for the affective and somatic scores were 2.08 (95% CI, 1.18-3.67) and 1.59 (95 CI, 0.87-2.91), respectively.
A major limitation of the current study includes the lack of available information on potential early-life confounders, such as social relationships and childhood health, which may have biased the results. Moreover, power limitations in the intrapair analyses limits stratification according to sex or zygosity status.
The investigators concluded that the current study of 6714 and 2559 twin pairs demonstrated that depressive mood (both total and affective and somatic symptomatology scores) at baseline is associated with a higher incidence of ischemic heart disease in both interpair and intrapair analyses. Thus, shared early-life environmental and genetic factors are not responsible for the link between depressive mood and ischemic heart disease reported among middle-aged and old adults.
Wium-Andersen MK, Wium-Andersen IK, Jørgensen MB, et al. The association between depressive mood and ischemic heart disease: a twin study. Acta Psychiatr Scand. 2019;140(3):265-274.