Emotion recognition impairment in Parkinson's disease patients without dementia

Purpose: Previous research has shown dementia and mild cognitive impairment to be present in some Parkinson's disease (PD) patients. Nevertheless, it is still not clear whether PD patients are also impaired on facial emotion recognition, nor it is whether this possible deficit is independent other cognitive impairment. The aim of this study is to assess the presence of emotion recognition deficits in a sample of PD patients with normal cognitive abilities, evaluated with several cognitive tasks widely used to detect cognitive impairment in this patient group.

Method: 40 non-demented (MMSE scores>25) PD patients and 19 healthy older adults matched on demographic characteristics took part in the study. All of them were evaluated with a neuropsychological battery including tests aimed to assess the cognitive domains mainly affected by PD, as well as a facial emotion recognition task.

Results: t-test analysis showed significant differences between PD and control groups in 6 cognitive tasks which were introduced in a sequential logistic regression analysis. The results confirmed the existence of a facial emotion recognition deficit in PD patients after controlling for demographic and cognitive characteristics of the participants.

Conclusion: Although none of the PD patients fulfilled criteria for dementia, many of them appeared to present deficits on recognition of facial emotions. This task should therefore be incorporated into future research to study the full range of early cognitive dysfunctions and non-motor symptoms presents in PD patients, and inclusion of this task in assessment protocols should be considered.