Supervisors info:
Λεωνίδας Στεφανής, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ.
Ελένη-Κλεάνθη Κατσουγιάννη, Καθηγήτρια , Ιατρική Σχολή, ΕΚΠΑ.
Παναγιώτα Τουλούμη, Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ.
Summary:
Background: Cognitive impairment is one of the most widespread non-motor symptoms of Parkinson’s disease. The Montreal Cognitive Assessment (MoCA) is a neuropsychological test often used to track mild cognitive impairment as well as dementia in Parkinson’s disease. In the Vavougios et al (2019) study, 5 phenotypes of cognitive impairment are highlighted, having as criteria the overall score in the MoCA test(MoCA total score) at the beginning of the follow up and the rate of cognitive impairment after 3 years. This survey examines these phenotypes with relation to the different dimensions of cognitive function, as they are determined by the subscales of the MoCA scale.
Methods: The data for this survey were drawn from the PPMI (Parkinson’s Progression Markers Initiative), a multi-centred observational clinical study, in which clinical and imaging data are collected and used by scientists to study the Parkinson’s disease progress. In particular, this survey analyses measurements of 350 patients with Parkinson’s disease who underwent the MoCA test in the beginning of the follow up and after the lapse of three years. This survey studies the phenotypes highlighted by the Vavougios et al (2019) study in respect of their form and progress through time, as well as the patient age and sex. The criterion for their form examination was the tracking of their performance in the MoCA subtests to which they are related. The application of the MCA (Multiple Correspondence Analysis) was chosen, aiming at finding patterns constituting combinations of performance in the subtests of the MoCA test, which are clustered, and also examining whether the phenotypes relate to these patterns.
Results: The 5 cognitive function declining phenotypes in patients with Parkinson’s disease highlighted in the Vavougios et al (2019) study are: a) Minimally Impaired Declining (MID), b) Cognitively Unimpaired Declining (CUD), c) Cognitively Unimpaired Stable (CUS), d) Minimally Impaired Stable (MIS) and e) Significantly Impaired Stable (SIS). This study has shown: The differences in the MID is that in the beginning, apart from the common features in both time periods (failure in Delayed Recall and Naming-Rhino), it is characterized by lack of Verbal Fluency and moderate performance in calculations, and, after a period of three years, by a lack of Abstraction, difficulty in Visuoconstructional Skills subtests and also difficulty in Attention and Concentration. In the CUD phenotype, apart from the lack of long-term memory- and maybe a slight decline-, after the period of three years there appears to be a failure in even more subtests (Visuoconstructional Skills, Verbal Fluency, Abstraction and Spatial and Temporal Orientation), therefore an overall cognitive functions decline. Patients of the CUS phenotype appear to have very good performance during the early and the late stages in the MoCA subtests (including Delayed Recall, Visuoconstructional Skills and Verbal Fluency), the only difference being that in the beginning they are characterized by performing well in the Vigilance subtest, while later, apart from the common characteristics of both periods, they show good Spatial and Temporal Orientation. In the SIS phenotype there appears to be an improvement, as it is characterized by failure in more subtests in the beginning than after the period of three years. Still, failure in Delayed Recall, Alternating Trail Making and Visuoconstructional Skills is observed both in the beginning and after the three-year period. Patients of the MIS phenotype, despite not showing good long-term memory in the beginning, are observed to succeed in the relevant subtest after the three-year period lapse. They are also characterized by failure in other subtests (Verbal Fluency and Sentence Repetition) in the beginning, but after three years they succeed in Successive Subtraction by 7, Visuoconstructional Skills and Backward Digit Span). Finally, age is related to the MID, CUD, and CUS phenotypes, unlike the MIS and SIS phenotypes. Sex is significantly related to the MID (male) phenotype and CUS (female) phenotype.
Conclusions: From the results of this study no predictions for future performance can be made based on the initial characteristics and MoCA subtest performance. However, some assumptions can be made: a) male patients with Parkinson’s disease, in their mid-60’s with mild cognitive impairment initially(diagnosed with Parkinson’s disease 2 years at most before the application of MoCA), failure in Delayed Recall, failure in Naming-Rhino and lack of Verbal Fluency, are assumed to exhibit a decline in their Cognitive Function (MID category), b) patients irrespective of sex and age, who are also characterized by mild cognitive impairment initially, with failure in Delayed Recall and lack of Verbal Fluency like the previous case but also with failure in Sentence Repetition mainly and not in Naming-Rhino (without being excluded, though) are assumed not to suffer any further decline (maybe even show some improvement) (MIS category), c) patients in their late-60’s with unimpaired cognitive function initially, with success in Delayed Recall, are assumed to suffer a decline in their cognitive function after three years (CUD category), d) female patients with Parkinson’s disease, in their late-50’s with unimpaired cognitive function initially, with success in most subtests, are assumed not to suffer cognitive function decline after three years (CUS category), e) patients irrespective of sex and age, characterized by significant cognitive impairment initially and failure in most subtests, are assumed to exhibit stabilized cognitive function (and maybe a slight improvement) after three years (SIS category).
