Comparative cognitive and neuropsychiatric profiles between Parkinson's disease, multiple system atrophy and progressive supranuclear palsy.

BACKGROUND: Parkinsonian syndromes are characterized by a wide spectrum of non-motor symptoms. A few studies explored cognitive deficits and neuropsychiatric symptoms in atypical parkinsonism compared to Parkinson's disease (PD). The study was performed to identify cognitive and neuropsychiatric differences between PD, multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) and to evaluate the influence of clinical features, depressive symptomatology and apathy on cognitive performances in the three groups.

METHODS: Fifty-five PD, 44 MSA and 42 PSP patients underwent cognitive tests assessing attention, language, memory, visuospatial and executive functions as well as scales assessing depression and apathy. Out of these patients, 20 PD, 20 MSA and 20 PSP patients were selected to be matched for age, education and global cognitive status. Within each whole patients group, correlational analysis was performed between clinical, behavioural and cognitive parameters.

RESULTS: The main difference among the groups matched was on cognitive tests exploring verbal learning, executive and linguistic functions. The PSP group was more impaired than the PD and MSA groups on cognitive tests assessing executive functions. On the other hand, MSA group obtained similar cognitive performance to the PD group. As to behavioural symptoms, in whole PSP and MSA groups, apathy and depression were more severe than in PD group, while apathy (but not depression) were more severe in the PSP group as compared to the MSA group.

CONCLUSIONS: The present study underlined the pervasiveness of cognitive deficits, apathy and depressive symptoms in PSP, whereas little cognitive differences were found between PD and MSA. The findings indirectly supported a dysfunction of prefronto-subcortical circuitries (i.e., dorsolateral prefrontal and limbic circuits) in PSP and PD. Cognitive similarities between MSA and PD reinforced the pivotal role of altered basal ganglia and corresponding frontal deafferentation in the occurrence of the cognitive deficits.