Objective: To analyze the effects of levodopa on affective ratings of emotional valence and arousal to rewarding, fearful and neutral stimuli in PD patients and matched controls.

Background: Dopamine and deep brain stimulation (DBS) of the subthalamic nucleus (STN) have been shown to affect different aspects of emotional and motivational processes in Parkinson’s disease (PD). STN DBS increased activity of the aversive motivational system: the valence of fearful stimuli was experienced as more negative with DBS switched on (1). However, it is not known if STN DBS mimics the effects of dopaminergic medication on subjective emotional experience.

Methods: We examined 15 PD patients (all men, aged 58.4 (SD 6) years, disease duration 15(SD 6)) and 20 male controls using the same affective task that was previously used to examine the effects of STN DBS. Patients were tested in the OFF- condition (3-days washout of dopamine agonists and an overnight withdrawal of levodopa) and the ON- condition (on levodopa, best motor improvement) in a balanced order. Subjects rated a series of 84 pictures depicting rewarding, fearful and neutral stimuli according to emotional valence (from unpleasant to pleasant) and arousal (from calm to excited) on separate visual scales ranging from 1 to 9. The effect of levodopa on motor symptoms was assessed using the Unified PD Rating Scale part III (UPDRS III).

Results: The UPDRS III scores decreased from 39.9(SD 10) in the OFF condition to 13.3(SD6) in the ON condition (P<.001). We did not find any significant differences in affective valence and arousal ratings (category specific and overall ratings) between ON- vs. OFF- condition or between the patients and the control group.

Conclusions: In contrast to the previously demonstrated impact of STN DBS on valence ratings to fearful stimuli, in this study we failed to demonstrate the effects of dopamine on subjective ratings of affective valence and arousal to rewarding and fearful stimuli. These results suggest that the effects of STN DBS on emotional processing may be caused by a different mechanism than an increase of dopaminergic input. Supported by GACR 16-13323S and PRVOUK P26/LF1/4. 1. Serranová T. et al. (2011) Subthalamic nucleus stimulation affects incentive salience attribution in Parkinson’s disease. Mov Disord.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/emotional-valence-and-arousal-ratings-from-rewarding-and-fearful-stimuli-are-not-influenced-by-levodopa-in-parkinsons-disease/