Validating the Montreal Cognitive Assessment for the Diagnosis of Mild Cognitive Impairment in Parkinson's Disease
Cognitive Deficits and Mood Disorders in Parkinson's Disease, 2008
Dementia affects up to 80 percent of Parkinson’s disease patients, and the prevalence of other dementias including Alzheimer’s disease is high in this age group. A need exists for a brief tool that can detect early cognitive impairment. The Montreal Cognitive Assessment (MoCA) is a 10-minute assessment developed to identify patients with mild cognitive impairment (MCI). Our pilot data strongly suggests that the MoCA is better able to detect cognitive impairment in PD patients than the currently used instruments.
In this project we will determine the ability of the MoCA for detecting MCI in PD patients and for following cognitive abilities by administering the MoCA and a series of cognitive tests to 140 PD patients. We will repeat the evaluations yearly for two years.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
A rapid screening test sensitive to cognitive impairment in PD is needed to optimize early detection of this disabling problem, to prompt full investigation, to trigger initiation of Symptoms & Side Effects treatment and to follow response to treatment. Also, once therapies become available to slow the progression of cognitive impairment in PD, early detection will be even more important. Because it is brief and easily administered, the MoCA has the potential to be the standard screening tool for cognitive impairment in PD if it has appropriate sensitivity and specificity.
By establishing the validity of the MoCA for the assessment of cognitive dysfunction in PD patients this study has the potential to improve the clinical care of PD patients by establishing the MoCA as a practical clinical tool to detect early cognitive impairment and to follow the efficacy of treatments over time.
We recruited 139 patients with Parkinson’s disease without dementia. Seventy one (51%) met criteria for mild cognitive impairment. We found that the cutoff that provides maximal accuracy for diagnosing mild cognitive impairment (MCI) was 26/27. At that cutoff, 71% of the patients were correctly classified as having MCI or not. At that cutoff, the MoCA detected 85% of individuals who had mild cognitive impairment according to our gold standard, however it incorrectly classified 44% of those without MCI as having MCI. The MMSE and the SCOPA-Cog’s maximal % correctly classified were somewhat less, at 65 and 63% respectively. Considering the purpose of the tests to screen for possible MCI the MoCA provides the best overall performance to correctly identify individuals with mild cognitive impairment when compared with the SCOPA-Cog or the MMSE. However, a substantial number of individuals without MCI will be flagged as possibly having cognitive impairment. Therefore an additional level of evaluation is required to confirm the disorder after screening with any of these tests.
Presentations & Publications
1. "Validating the Montreal Cognitive Assessment for the Diagnosis of Mild Cognitive Impairment in Parkinson's Disease" was presented at the American Academy of Neurology 63rd Annual Meeting, April 9 to April 16, 2011 at Honolulu, Hawaii.
2. What’s in a hippo? The meaning of a hippo response on the Montreal Cognitive Assessment, presented at the International Congress of Movement Disorders, 2011 in Toronto, Canada. This work has also been submitted for peer review in manuscript form.
Associate Professor at University Health Network, University of Toronto
Location: Toronto, Canada