Impairment of Emotional Memory and Ability to Identify Emotional States in Patients with Parkinson's Disease

Parkinson's disease (PD) is characterized not only by a progressive movement disorder but also by a variety of mental disorders, which can be arbitrarily divided into cognitive and emotional–personality disorders. The aim of this investigation was to study the relationship between cognitive and emotional–personality disturbances in patients with PD during learning of emotionally significant words and visual recognition of emotional states. The volume and stability of recall of neutral and expressive words were significantly lower in patients than in healthy subjects, whereas the parameters of word recognition were similar in both groups. Unlike in healthy subjects, the characteristics of recall of neutral and expressive words in patients did not differ considerably. Patients with PD significantly more often incorrectly interpreted emotional states shown in pictures, particularly negative emotions. Deficit in retention of expressive words and recognition of emotional states correlated with the severity of motor and cognitive disorders, particularly of attention and executive dysfunction. The results of our study can be explained by a dissociation of the cognitive and motivational–affective functions in PD because of a disconnection between the basal ganglia, the limbic structures, and the frontal cortex. This dissociation tended to increase with progress of the disease.