ABSTRACT
BACKGROUND AND PURPOSE: Impulsivity is an aspect of personality and a major component of multiple neuropsychiatric conditions. In Parkinson's disease, it has been associated with the expression of impulse control disorders, a highly prevalent non-motor complication. Even though multiple tests of impulsivity have been used in this context, the impact of test choice has not been addressed. The aim was to evaluate whether different impulsivity measures in Parkinson's disease share substantial inter-scale and anatomical correlations or rather mirror different underlying phenomena. METHODS: In a consecutive sample of 89 Parkinson's disease patients without impulse control disorders, four common tests were evaluated assessing different aspects of impulsivity: impulsiveness trait, decisions under implicit risk with and without losses, and delay discounting. Correlations among test scores were analysed and each score was used as a regressor in a set of grey matter volume (GMV) voxel-based morphometry analyses to explore their brain structural correlates. RESULTS: No significant correlations were found between the different impulsivity tests. Furthermore, their structural brain correlates were divergent. Impulsiveness trait appeared to be associated with lower GMV in dorsal-lateral prefrontal cortices, implicit risk (with losses) with higher GMV in the left nucleus accumbens and lower left insular GMV, implicit risk (without losses) with higher GMV in the left lingual gyrus and lower GMV in the gyri recti and delay discounting with higher GMV in the left nucleus accumbens. CONCLUSIONS: In Parkinson's disease, different impulsivity measures reflect very dissimilar behavioural and brain structural correlates. Our results suggest that parkinsonian impulsivity is not a unitary phenomenon but rather a heterogeneous entity.
Subject(s)
Impulsive Behavior , Parkinson Disease , Disruptive, Impulse Control, and Conduct Disorders/diagnostic imaging , Disruptive, Impulse Control, and Conduct Disorders/etiology , Gray Matter/diagnostic imaging , Humans , Magnetic Resonance Imaging , Neuroimaging , Parkinson Disease/complications , Parkinson Disease/diagnostic imagingABSTRACT
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Subject(s)
Humans , Female , Adult , Diffuse Cerebral Sclerosis of Schilder/complications , Diffuse Cerebral Sclerosis of Schilder/etiology , Diffuse Cerebral Sclerosis of Schilder , Paresis/diagnosis , Methylprednisolone/therapeutic use , Hydroxymethylglutaryl-CoA Reductase Inhibitors/therapeutic use , Platelet Aggregation Inhibitors/therapeutic use , Diffuse Cerebral Sclerosis of Schilder/drug therapy , Diffuse Cerebral Sclerosis of Schilder/physiopathology , Hypesthesia/complications , Skull/pathology , Skull , Echocardiography , Diagnosis, DifferentialABSTRACT
Impulse control disorders (ICDs) may arise in Parkinson's disease (PD) in relation to the use of dopamine agonists (DA). A dysfunction of reward circuits is considered the main underlying mechanism. Neuroimaging has been largely used in this setting to understand the structure of the reward system and its abnormalities brought by exogenous stimulation in PD. Dopaminergic changes, such as increased dopamine release, reduced dopamine transporter activity and other changes, have been shown to be a consistent feature of ICDs in PD. Beyond the striatum, alterations of prefrontal cortical function may also impact an individuals' propensity for impulsivity. Neuroimaging is advancing our knowledge of the mechanisms involved in the development of these behavioral addictions. An increased understanding of these disorders may lead to the discovery of new therapeutic targets, or the identification of risk factors for the development of these disorders.
