Risk for major depressive disorder was highest among grandchildren with two previous generations affected by the disorder, suggesting the potential significance of family history of depression beyond two generations.
“The increased risk of psychiatric disorders in the offspring of depressed parents is well known. Whether this risk is transmitted beyond two generations is less well known. This information is important for detecting individuals who may benefit from early intervention and may be candidates for biological marker studies,” Myrna M. Weissman, PhD, of Columbia University, New York City, and colleagues wrote. “There are no published studies of depression examining three generations with grandchildren in the age of risk for depression and with direct interviews of all family members.”
To assess familial aggregation of psychiatric disorder and functioning in grandchildren by their biological parents’ and grandparents’ depression status, researchers interviewed a longitudinal retrospective cohort family sample of 251 grandchildren a mean of two times and their biological parents a mean of 4.6 times and grandparents up to 30 years.
Biological children of parents with depression had significantly higher risk for major depressive disorder (MDD) (HR = 2.02; 95% CI, 1.08-3.79; P = .03), any disruptive disorder (HR = 1.7; 95% CI, 1.05-2.75; P = .03), substance dependence (HR = 2.96; 95% CI, 1.24-7.08; P = .01), any suicidal ideation or gesture (HR = 2.44; 95% CI, 1.28-4.66; P = .007), and poor functioning (P < .001), compared with children of parents without depression.
When three generations were assessed stratified by parental and grandparental depression status, association between parental MDD and grandchild’s MDD varied with grandparental depression status. Risk for MDD was highest among grandchildren with parents and grandparents with depression.
Among grandchildren with grandparents without depression, those with parents with depression had overall poorer functioning compared with their peers with parents without depression (P = .01). Rates for all other disorders were not higher among grandchildren with grandparents without depression and parents with depression.
Potential confounding variables did not significantly affect the association between grandchild outcomes and parental or grandparental depression, according to researchers.
“These findings show the potential value of extending family history of depression beyond two generations. There is now considerable data showing the positive effects on children of successful treatment of a depressed parent. The specificity of the transmission of depression across three generations suggests that this group might be a homogeneous sample for future biological marker studies,” the researchers concluded. – by Amanda Oldt
Weissman reports receiving funding from the NIMH, National Institute on Drug Abuse, National Alliance for Research on Schizophrenia and Depression, Sackler Institute for Developmental Psychobiology, and John Templeton Foundation and receiving royalties from Oxford University Press, Perseus Books Group, APA Publishing, and Multi-Health Systems (all in the past 3 years). Please see the full study for a list of all authors’ relevant financial disclosures.