THE ASSOCIATION BETWEEN PERCEPTION OF COGNITIVE DECLINE AND MILD COGNITIVE IMPAIRMENT IN NON-DEMENTED PATIENTS WITH PARKINSON'S DISEASE

Mild cognitive impairment (MCI) is common in patients with Parkinson's disease (PD). The self-report of cognitive decline could facilitate the diagnosis of MCI. However, the perception of a cognitive decline in patients with PD may be limited due to the presence of apathy which is also common in PD. This study is aimed to evaluate the association between self- and informant-perception of cognitive decline, and the objective cognitive decline in non-demented PD patients. 73 non-demented, non-depressed patients with PD were included from Parkinson clinic at Siriraj Hospital. Perception of cognitive decline was assessed by using the Cognitive Change Index (CCI), Thai-version. The Montreal Cognitive Assessment (MoCA) Thai-version was used to assess the objective cognitive decline and to diagnose a mild cognitive impairment (PD-MCI) according to Movement Disorder Society guideline. Association of the diagnosis of PD-MCI, MoCA score and CCI scores obtained from subjects (CCI-S) and their informants (CCI-I) was analyzed. Apathy was diagnosed by the 2009 proposed diagnostic criteria for apathy in Alzheimer's disease and other neuropsychiatric disorders. There were 19 cognitively-normal PD patients (PD-CN) and 54 patients with PD-MCI. CCI-I score was significantly higher in the PD-MCI group as compared to PD-CN (37.7±14.8, 29.4±5.7, respectively, p=0.001), but not the CCI-S (p=0.59). However, both CCI-I and CCI-S scores were not correlated with MoCA score (p=0.82 and 0.36, respectively). 19 (35.2%) participants were diagnosed as having apathy, and all of them were in the PD-MCI group. No patients in the PD-CN group had apathy. Only the informant perception of cognitive decline, as measured by the CCI-I Thai-version, and the diagnosis of apathy are associated with the diagnosis of MCI in Thai patients with PD. Integration of a report of cognitive deficit from an informant and the diagnosis of apathy could help in the diagnosis of PD-MCI. More studies with comprehensive neuropsychiatric tests are needed to demonstrate the relationship between the perception of cognitive decline and objective cognitive performance.