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Such information could help guide early intervention in individuals considered to be at high familial risk for developing MDD, Lynn MacKenzie, M.A., of Dalhousie University in Halifax, Nova Scotia, and colleagues wrote.
MacKenzie and colleagues compiled data from 54 individual studies that assessed cognition; the studies included 3,246 first-degree relatives of people with MDD (such as children or siblings) and 5,222 people without a first-degree relative diagnosed with MDD, bipolar disorder, or schizophrenia.
The researchers found that compared with the control group, first-degree relatives of individuals with MDD performed worse on several cognitive tests—including assessments of verbal intelligence, perception, memory, and language. First-degree relatives of people with MDD also had slightly lower academic performance on average compared with controls. There were no statistical differences in tests for attention, processing speed, executive function, hot cognition (cognitive ability during an emotionally aroused state), and psychomotor skills such as coordination.
“There are several possible explanations for impaired cognitive performance in first-degree relatives of individuals with MDD. The lower cognitive ability seen in relatives of individuals with MDD may reflect genetic and social factors associated with the risk of MDD,” Mackenzie and colleagues wrote. “Cognition in relatives may also be affected by environmental factors, such as poverty and low socioeconomic status, that may run in families alongside depression and affect even those who do not develop depressive disorders.”
(Image: iStock/skynesher)
