Neuropsychological features of patients with Parkinson's disease and impulse control disorders

Impulse control disorders (ICDs) are frequent in Parkinson's disease (PD). Aim of the present study was to investigate cognition and behaviour in PD patients with and without ICDs, in order to identify potential early clinical features which might be associated to the development of ICDs. We recruited 17 PD patients with ICDs and 17 without ICDs, matched for several clinical variables, without clinically significant cognitive deficits. Assessments included behavioural scales and a neuropsychological battery, including the Iowa Gambling Task (IGT). In patients with ICDs, the total score of the BIS and the Motor Impulsivity subscore were significantly higher than in patients without ICDs. In patients with ICDs, we observed only statistical trends towards a worse performance on neuropsychological tasks (go-no-go subtest of the Frontal Assessment Battery, oral verb naming task, copying of drawings with landmarks) sensitive to frontal lobe dysfunction (FLD) and on the IGT (loss of a greater amount of money, more risky choices). As compared to patients without ICDs, they reported a more than threefold number of errors on the interference subtest of Stroop test, which is also sensitive to FLD. Although this study did not show any significant difference between PD patients presenting ICDs as compared with patients without ICDs on neuropsychological variables, some preliminary evidence was detected suggesting a trend toward a worse performance of the PD-ICD group on few neuropsychological tasks which are at least partially sensitive to frontal lobe dysfunction, including tasks sensitive to dysfunction of ventral fronto-striatal loops.