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Past Psychomotor Symptoms Predict Abnormal Reward-Based Reinforcement Learning in Remitted MDD
A history of psychomotor retardation predicts altered reward-based reinforcement learning in people with remitted major depressive disorder (MDD), according to a study published in the Journal of Psychiatric Research.
“Reward-based reinforcement learning impairments are common in major depressive disorder, but it is unclear which aspects of reward-based reinforcement learning are disrupted in remitted MDD,” wrote lead and corresponding author Allison M. Letkiewicz, PhD, of Northwestern University, and coauthors.
Neurobiological substrates involved in reward-based reinforcement learning are also involved in psychomotor retardation, researchers explained. For the study, they investigated whether 34 individuals with remitted MDD and a history of psychomotor retardation showed differences in reward-based reinforcement learning compared with 44 individuals with remitted MDD but no past psychomotor retardation, as well as 90 healthy control subjects.
Quiz: Are the relatives of patients with MDD at risk of developing the disorder?
Investigators were interested specifically in two parameters of reward-based reinforcement learning: learning rates and reward sensitivity.
During a reward-based reinforcement learning task, individuals with remitted MDD and past psychomotor retardation demonstrated lower learning rates but not reduced sensitivity to rewards, the study showed. Individuals with remitted MDD and no history of psychomotor retardation, however, did not differ significantly from healthy control subjects on learning rates or reward sensitivity.
The findings were not affected by current psychopathology symptoms, follow-up analysis found.
“Abnormal reward-related reinforcement learning may reflect a scar of past depressive episodes that contained psychomotor symptoms,” researchers wrote, “or a trait-like deficit that preceded these episodes.”
Nevertheless, they advised that “targeting residual psychomotor retardation symptoms in individuals with a history of MDD and/or reward-based reinforcement learning in individuals with a history of psychomotor retardation may help to prevent relapse into future depressive episodes,” Psychiatry Advisor reported.
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