The efficacy of continuous subcutaneous apomorphine infusion (CSAI) for motor complications of Parkinson's disease (PD) is established. However, its effect on cognition and behavior remains controversial. The main objective of this systematic review was to describe the existing literature on the effects of CSAI on cognition and behavior and to determine the quality for each study.

PubMed/Medline, Embase, APA PsycInfo®, and Cochrane Library databases were searched, following PRISMA recommendations. Only longitudinal studies evaluating the effect of CSAI on cognition (global cognition, executive functions, visuospatial abilities, language, memory, attention, social cognition) and/or behavior (depression, anxiety, apathy, psychotic symptoms, impulse control disorders, neuropsychiatric fluctuations) in PD were included. The quality of the included studies was also assessed with a questionnaire.

Twenty-three longitudinal studies evaluated the effect of CSAI on cognition and/or behavior. Overall, results were suggestive of positive effects, notably on executive functions and emotion recognition. However, there were some reports of cognitive slowing and long-term global cognitive deterioration. At the behavioral level, no study showed significant adverse effect of CSAI. Occasionally, a slight improvement of depression, anxiety, apathy, and neuropsychiatric fluctuations was reported. Nevertheless, only four studies met good quality criteria and controlled study regarding cognition were lacking.

The results suggest that CSAI has no obvious negative effects on cognition and behavior in PD. This treatment even shows promise in reducing certain symptoms such as neuropsychiatric fluctuations. However, due to methodological limitations in many studies, no robust conclusions can be drawn. Further multicenter controlled trials are needed to confirm these results.