Researchers have known for some time that young people whose parents suffer from major depressive disorder (MDD) face a heightened risk for depression — but now they have found that if the family history of MDD extends to grandparents, the risk is increased threefold.
The new data points to the value of screening for MDD in more than just two generations.
"With the use of data from all three generations, it became clear that embedded within the high-risk sample was a group of children at extremely high risk for MDD, namely, the grandchildren with two previous generations affected with MDD," the authors, led by Myrna Weissman, PhD, of Columbia University and New York State Psychiatric Institute, New York City, report.
Until this discovery, no published research on depression has included direct interviews that span three generations of family members.
But in this longitudinal, backward-looking study using data from a 30-year span (January 1982 to June 2015), 251 grandchildren with a mean age of 18 were questioned a roughly two times each. Their biological parents were surveyed a mean of 4.6 times, and the grandparents were interviewed over a period of up to 30 years.
The groups had no significant differences in terms of educational attainment, age, or sex, writes Nancy A. Melville for Medscape.
Sixty-two families chosen from the Yale Depression Research Unit in New Haven, Connecticut were included in the project. The biological children of depressed parents, compared to parents who were not depressed, were twice as likely to have MDD. Young ones with depressed parents also had increased incidences of disruptive disorders, substance dependence, suicidal ideation or gesture, and poor functioning.
Kids who also had one or more grandparents with depression had the highest rates of psychiatric disorders, with 71% having at least one disorder. Of those whose mothers and fathers had depression, but whose grandparents did not, 63% had disorders, and 51.4% of children whose parents and grandparents did not have MDD had disorders.
The risk was almost three times greater when the parent and the grandparent had depression compared to those not having a parent with MDD.
"The take-home message from this is that depression is transmitted across generations and grandchildren, and those with two previously affected generations are at the highest risk," Weissman added.
IAN reports that the study was published in the journal JAMA Psychiatry. Children who have MDD-afflicted parents and grandparents are at such a high rate of risk for MDD that it would be prudent to determine the family history of depression beyond two generations.
Another newly published report has found that there is a slight increase in the number of US teens who are experiencing episodes of depression, writes Sara G. Miller of LiveScience.
From 2013 to 2014, approximately one in nine teenagers in the US had a major depressive episode, which is an increase from the approximate one in 10 teens from 2012-2013, says data from the government's National Surveys on Drug Use and Health.
Weissman notes that it is uncertain if these findings mean the numbers will continue to rise. To know that would necessitate tracking trends over a longer amount of time.
There are three factors that could explain the small increase, said Ardesheer Talati, an assistant professor of clinical neurobiology in psychiatry at Columbia University and New York State Psychiatric Institute. First, the increased awareness of mental illness means more young people are seeing doctors to be evaluated for depression. Next, teens are under much more stress than they were in the past, with stressors such as academic performance, family dysfunction, and social interactions.
And the manner in which depression is diagnosed is changing, with the definition of the condition also becoming broader. Talati adds that this could mean more teens are falling somewhere on the spectrum than was recognized in the past.