Low Positive Affect in Childhood May Lead to Eventual Depression

According to a recent study, low positive affect (PA) may be a premature liability factor for unipolar depressive disorder in at-risk children, and was proven to have a greater impact than high negative affect (NA).

Thomas M. Olino from the University of Pittsburgh School of Medicine and fellow researchers analyzed the developmental trajectories of PA and NA in 202 child participants whose families had histories of depressive disorders. The children’s ages ranged from late infancy to nine years old.

The researchers determined PA and NA in the child participants in up to seven annual structured laboratory tasks.

Of the 140 mothers of the child participants, sixty had a history of juvenile-onset unipolar depressive disorder while eighty had no history of major psychopathology.

The investigators discovered that PA increased in a similar, linear fashion for all of the children as time progressed. Individual differences were seen frequently in early PA.

The children whose mothers suffered from lifetime unipolar depression were found to have perpetually lower levels of PA in comparison to the group of control participants; this finding is a significant connection, and remains so even after the researchers adjusted for current maternal depression and affect displays.

They also observed a significant linear reduction in NA in children across time, but no considerable 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 wrote.

This study is published in the July issue of the Journal of Child Psychology and Psychiatry.