Siblings of those with mental illness may be at greater risk for depression

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Those who have a brother or sister with a mental illness or a low IQ can be influenced by their illness, according to a new study, possibly putting them at higher risk for bouts of depression and other challenges during their lives.

Data from the Wisconsin Longitudinal Study, a 46-year report that includes 5,800 pairs of siblings, was used for the study, published in the December issue of the Journal of Family Psychology. Researchers from the University of Wisconsin-Madison and Georgia State University focused on 351 men and women who had at least one brother or sister with a low IQ (85 or below) or a mental illness that included a depressive or anxiety disorder. A group of 791 people who didn’t have a mentally disabled sibling acted as a control group.

Among the findings, siblings of adults who had low IQs were 18% more likely to live in the same state with their brother or sister than those in the control group. But they also felt less emotionally close to their siblings and had, on average, fewer contacts than siblings in the control group.

Siblings of those with mental illness were 63% more apt to say they’ve had a depressive incident in their lives versus those in the control group (Researchers defined those incidents as lasting for two weeks or more, and could include feeling lonely, crying and losing their appetite.).

Some gender differences were noted, too. Those who had a mentally ill brother had lower well-being scores than similar pairings in the control group.

Researchers note that having a mentally disabled sibling may not be the sole cause of the differences seen. Other issues could come into play, such as having a genetic predisposition to depression and other mental disorders. Strained family dynamics could play a part as well.

-- Jeannine Stein