[Impairments of Neurocognitive Mechanisms of Decision-Making in Depression.]

ABSTRACT

A multidisciplinary clinical-psychological-neurophysiological study has been performed in 28 depressive patients (females, aged 18-56) and 50 healthy volunteers (females, aged 18-55) in order to analyze the relationships between the impairments of neurocognitive mechanisms of decision-making based on logics and considerations or on emotional experience (emotional learning) in uncertain situation and clinical and neurophysiological signs of depression. The severity of depression was assessed quantitatively using Hamilton's Depression Rating Scale (HDRS-17). Tests "10 words", Wisconsin Card Sorting Test (WCST), and Iowa Gambling Task (IGT) were used for quantitative assessment of cognitive functions. Multichannel resting EEG was recorded in all depressive patients in order to assess the brain functional state. Neurocognitive deficit was observed in all the patients; its pronounce correlated positively with the severity of depression. The ability to make decisions based on both logic and considerations (in WCST), which is associated with EEG signs of hypofrontality, and on emotional learning (in IGT) was impaired. Only in depressive patients reduced ability to make rational decisions based on logics and considerations resulttd in a compensatory shift towards decision-making based on emotions, which led to relatively higher results of emotional learning. The data suggests that hypofrontality causes difficulties in making decisions that requires logical reasoning and the disinhibition of subcortical (including hippocampal) brain structures, the activation of which provides better results of emotional learning.