Relationship between poor decision-making process and fatigue perception in Parkinson's disease patients.

Background: Fatigue is a common non-motor symptom in Parkinson's disease patients. The reasons for its perception are not completely understood. One suggested possibility might be that perceived fatigue is related with abnormal interpretation of somatic symptoms. It has been described that somatic markers misinterpretation leads to poor decision-making. We hypothesized that fatigued Parkinson's disease patients would show poorer performance than non-fatigued in a decision-making task.

Methods: To test our hypothesis, 89 Parkinson's disease patients were assessed for the presence of fatigue using the Parkinson Fatigue Scale. All patients were also administered scales evaluating psychopathology and neuropsychological tests, including the Iowa Gambling Task.

Results: 33 (37.1%) patients fulfilled the established criteria for fatigue. In the univariate analysis, fatigued patients showed higher levels of anxiety (state: p = 0.001, trait: p < 0.001), impulsivity (p = 0.051), and depression (p < 0.001) than non-fatigued patients. No statistically significant differences in other neuropsychological test results (Stroop, Trail Making Test, Tower of London) were found between fatigued and non-fatigued patients except for the Iowa Gambling Task, in which fatigued patients showed poorer performance (p = 0.001) after controlling for confounding factors.

Conclusions: These results suggest that fatigued Parkinson's disease patients may present abnormal decision-making process, which may reflect abnormal processing of somatic markers when faced with an activity that requires effort.