These results provide evidence for ToM impairments early in the course of PD. Recognition of ToM impairments in early PD is important, as these deficits may impact patients' social interactions and quality of life.

We evaluated whether patients with early-onset Parkinson's disease (EOPD) have a different clinical profile and pharmacological response than those with late-onset disease (LOPD). We performed a retrospective analysis and an acute pharmacological challenge with L-Dopa in 34 EOPD (age at onset between 21 and 40 years) and 34 LOPD (onset after age 60) patients. All patients completed a structured questionnaire cross-checked against medical record charts and underwent an acute levodopa test. Most significant differences were in the mode of onset, time of diagnosis, and degree of initial improvement. We did not observe differences with regard to motor fluctuations. The acute levodopa test showed no differences in latency to response onset between groups. However, the magnitude of the response was greater and the duration shorter in EOPD patients. Younger patients had greater reductions in bradykinesia scores, whereas posture/gait symptomatology was less responsive in older patients. The type and severity of dyskinesias also differed significantly between groups. Our findings suggest that central pharmacokinetics, pharmacodynamics, and possibly, nondopaminergic systems play a role in the age-related differences observed in Parkinson's disease.

BackgroundWe recently demonstrated that decline in fluid intelligence is a substantial contributor to frontal deficits. For some classical ‘executive’ tasks, such as the Wisconsin Card Sorting Test (WCST) and Verbal Fluency, frontal deficits were entirely explained by fluid intelligence. However, on a second set of frontal tasks, deficits remained even after statistically controlling for this factor. These tasks included tests of theory of mind and multitasking. As frontal dysfunction is the most frequent cognitive deficit observed in early Parkinson's disease (PD), the present study aimed to determine the role of fluid intelligence in such deficits.MethodWe assessed patients with PD (n=32) and control subjects (n=22) with the aforementioned frontal tests and with a test of fluid intelligence. Group performance was compared and fluid intelligence was introduced as a covariate to determine its role in frontal deficits shown by PD patients.ResultsIn line with our previous results, scores on the WCST and Verbal Fluency were closely linked to fluid intelligence. Significant patient–control differences were eliminated or at least substantially reduced once fluid intelligence was introduced as a covariate. However, for tasks of theory of mind and multitasking, deficits remained even after fluid intelligence was statistically controlled.ConclusionsThe present results suggest that clinical assessment of neuropsychological deficits in PD should include tests of fluid intelligence, together with one or more specific tasks that allow for the assessment of residual frontal deficits associated with theory of mind and multitasking.

Objective: To demonstrate the usefulness of incorporating the Executive and Social Cognition Battery (ESCB) to detect executive and social cognition deficits, which are otherwise not captured by more “classical” executive tests in early Parkinson disease (PD). Background: PD is a neurodegenerative disorder that includes executive and social cognition deficits. While cognitive assessment in PD still relies on classical executive tasks to detect frontal deficits, these traditional tests often fail to uncover subtle, yet relevant, frontal impairment. Methods: We evaluated 39 PD patients and 47 controls with a battery of classical executive tests and the ESCB. The ESCB includes a series of tasks that more closely resemble real-life activities and have been previously shown to be useful in detecting executive deficits in other neuropsychiatric disorders with frontal involvement. Results: We observed that both batteries used in a complementary way yielded better results, as 15 of the 39 patients presented deficits only on some of the ESCB tests, but not on the classical battery, while 5 patients presented deficits only on some tests of the classical battery, but not on the ESCB. Fourteen patients presented deficits on some tests of either battery, and 5 patients did not present deficits on any of the tests. Conclusions: We found that, used along with traditional neuropsychological tasks, the ESCB may be useful in providing a more comprehensive evaluation of frontal dysfunction among patients with PD, thus contributing to the early diagnosis of cognitive disorders in this patient population.