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Genetic factors, rearing experiences influence major depression in offspring
Genetic factors and rearing experiences equally impact the parent-offspring resemblance for treated major depression and alters the risk for major depression in the child, according to data published in JAMA Psychiatry.
“Renewed interest in adoption studies of psychiatric disorders has emerged largely owing to the availability of national record linkages in Scandinavia. However, to our knowledge, such studies have used psychiatric diagnoses from hospital admissions and sometimes specialist outpatient care,” Kenneth S. Kendler, MD, from Virginia Institute for Psychiatric and Behavioral Genetics at Virginia Commonwealth University, and colleagues wrote. “For [major depression], such samples are unlikely to be representative because most treated cases of [major depression] are seen solely in outpatient primary care settings.”
Prior research has examined the relationship between sibling resemblance and major depression, but the sources of resemblance across generations remains unknown, according to the researchers. Kendler and colleagues performed a Swedish population-register-based study to determine the significance of genetic and rearing effects on the parent-offspring resemblance for treated major depression. Using data collected from Jan. 1, 1960, through Dec. 31, 2016, the investigators tested for parent-child resemblance for genes plus rearing, genes-only and rearing-only associations among five family types: intact, adoptive, not-lived-with father, stepfather and triparental.
Of 2,269,552 offspring included in the study, the weighted tetrachoric correlations for major depression across family types and across mothers and fathers were: r = 0.17 (95% CI, 0.16-0.17) for genes plus rearing; r = 0.08 (95% CI, 0.06-0.09) for genes-only; and r = 0.08 (95% CI, 0.07-0.09) for rearing-only parent-child associations. Only the genes plus rearing connection varied significantly between mothers (r = 0.18; 95% CI, 0.18-0.18) and fathers (r = 0.15; 95% CI, 0.15-0.16).
The prevalence rate of major depression in child and biological parents were approximately 50% lower in the intact families than in the not-lived-with father, stepfather, adoptive and triparental families, but the rate in stepparents and adoptive parents were like those in intact families. Parents with clinical major depression diagnosis equally affected the risk for major depression in children with intact families. The impact of affected biological and affected adoptive parents on adoptee risk for major depression acted additively in adoptive families.
“Parent-offspring transmission of risk for [major depression] is the result of genetic factors and rearing experiences to an approximately equal degree. These two forms of cross-generational transmission appear to act additively on offspring [major depression] risk,” Kendler and colleagues wrote. “Although much of the genetic research on [major depression] has recently focused on the role of molecular variants, our results suggest that environmental processes also affect appreciably the tendency for [major depression] to aggregate within families.” – by Savannah Demko
Disclosure : The authors report no relevant financial disclosures.