A Hospital-Based Twin Register of the Heritability of DSM-IV Unipolar Depression

Abstract

Liability to DSM-IV major depression has a substantial heritable component, and there is no evidence of an effect of shared family environment. Some proband characteristics, especially shorter duration of episodes, may be associated with a larger degree of genetic determination.

Major Depressive Disorder in a Community-Based Twin Sample: Are There Different Genetic and Environmental Contributions for Men and Women?

“…10,13 Both studies reported no sex differences in heritability and much higher estimates of heritability (60% 10 to 70% 13 heritability). Though both studies had a large number of clinically ascertained twin pairs (217 clinically ascertained pairs of 486 total pairs 10 and 177 clinically ascertained pairs 13 ), their power to detect modest sex differences in heritability was likely low. Both studies had several important methodological differences from the current study that may contribute to differences in findings.…”

“…[7][8][9] On the other hand, twin studies consistently have supported genetic effects in the development of depression. [10][11][12][13][14] A population-based sample of twins from Virginia showed modest genetic influence (heritability 39%-42%) 11,14 on the development of DSM-III-R major depressive disorder. A similar finding was seen in a sample of male twins recruited from members of the military during the Vietnam War era (heritability 36%).…”

“…In the study by Kendler et al, 10 twins were clinically ascertained and matched with a population-based control group, assessments were done by questionnaire, and both major depressive disorder and bipolar disorder were combined in the analyses. In the report by McGuffin et al, 13 twins were also clinically ascertained, population estimates of lifetime rates of major depressive disorder were used, assessments were a synthesis of personal interviews when available and medical records, and some assessments were not blinded. The simple explanation that twins recruited from a treatment setting for depression had a more severe syndrome and thus a more heritable syndrome cannot explicate the differences in heritability estimates, since we found no increase in heritability with a more stringent definition of depression.…”

The implications of gene–environment interactions in depression: will cause inform cure?

“…8 However, these social factors account for relatively smaller proportion of depression in clinically ascertained samples 9,10 and fail to explain the grater differences in risk of depression between monozygotic compared to dizygotic twins. 11,12 The evidence for genetic influences on depression consists primarily of twin studies. The higher depression concordance rates in monozygotic than in dizygotic twins are replicable, but the degree of genetic contribution gives a mirror image of the social studies: it is larger in clinically ascertained than in community-based samples.…”

Molecular epidemiology of major depressive disorder

“…The heritability of major depressive disorder is likely to be in the range of 31-42% [11]. Similarly, heritability based on twin studies is 40-50% [70][71][72][73][74][75] and adoption studies also support a role for genetic factors [76][77][78]. In comparison, the heritabilities of schizophrenia and bipolar disorder are estimated to be approximately 70% [11].…”