Introduction: Theory-of-mind (ToM) refers to the ability to understand and predict the behaviour of others based on their mental states. Research from brain imaging and lesion studies indicate that the frontal lobes are both involved and necessary to understand mental states.
Methods: A total of 13 people with Parkinson's disease were compared with 11 age-matched controls on tasks involving ToM, based on the hypothesis that the frontal lobes are affected by Parkinson's disease. The four tasks included both ToM and non-ToM components, such as memory, to investigate the specific nature of the deficit.
Results: The group with Parkinson's disease scored significantly lower on three out of four of the ToM components of the tasks, relative to controls, but were not impaired on any of the non-ToM components of the four tasks.
Conclusion: The results suggest the impairment was specific to ToM and thus have implications for a dedicated specific ToM module.