Low Positive Affect in Childhood Factors Into Eventual Depression

More important factor than high negative affect for children with maternal history of depression

THURSDAY, July 14 (HealthDay News) -- Low positive affect (PA) may be an early vulnerability factor for unipolar depressive disorder in at-risk children, and has more of an impact than high negative affect (NA), according to a study published in the July issue of the Journal of Child Psychology and Psychiatry.

Thomas M. Olino, Ph.D., from the University of Pittsburgh School of Medicine, and colleagues assessed the developmental trajectories of PA and NA in 202 children, aged from late infancy to 9 years, at familial risk for depressive disorders. Of the children's 140 mothers, 60 had a history of juvenile-onset unipolar depressive disorder and 80 had no history of major psychopathology. PA and NA were identified through the children participating in up to seven annual structured laboratory tasks.

The investigators found that PA increased linearly and in a similar fashion for all of the children across time, with individual differences seen in early PA. The children of mothers with lifetime unipolar depression had consistently lower levels of PA compared to the control group, a significant association even after adjusting for current maternal depression and affect displays. A significant linear decrease in NA was observed in children across time, but no significant inter-individual differences were observed in early NA or the rate of change in NA.

"Attenuated PA (rather than excessive NA) may be an early vulnerability factor for eventual unipolar depressive disorder in at-risk children and may represent one pathway through which depression is transmitted," the authors write.

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