Mild cognitive impairment and dementia in early-onset Parkinson’s disease: a comparative study across disease duration

Ana N. Seubert-Ravelo, Residency in Clinical Neuropsychology, Interdisciplinary Research Unit in Health Sciences and Education, Faculty of Higher Studies Iztacala, UNAM, Tlalnepantla, State of Mexico, Mexico
M. Guillermina Yáñez-Téllez, Residency in Clinical Neuropsychology, Interdisciplinary Research Unit in Health Sciences and Education, Faculty of Higher Studies Iztacala, UNAM, Tlalnepantla, State of Mexico, Mexico
Gabriel A. Neri-Nani, Neurology Service, Dr. Bernardo Sepúlveda Gutiérrez Specialty Hospital, Centro Médico Nacional Siglo XXI, IMSS, Mexico City, Mexico
Alejandra Calderón-Vallejo, Neurology Service, Dr. Bernardo Sepúlveda Gutiérrez Specialty Hospital, Centro Médico Nacional Siglo XXI, IMSS, Mexico City, Mexico
Julieta Moreno-Villagómez, Residency in Clinical Neuropsychology, Interdisciplinary Research Unit in Health Sciences and Education, Faculty of Higher Studies Iztacala, UNAM, Tlalnepantla, State of Mexico, Mexico
Mayaro Ortega-Luyando, Residency in Clinical Neuropsychology, Interdisciplinary Research Unit in Health Sciences and Education, Faculty of Higher Studies Iztacala, UNAM, Tlalnepantla, State of Mexico, Mexico

Background: Few studies have analyzed the frequency of Parkinson’s disease (PD) associated mild cognitive impairment (PD-MCI) or dementia (PD-D), and its association with disease duration in the specific population of early-onset PD (EOPD). Objective: To describe and compare the frequency of PD-MCI and PD-D in patients with EOPD with short-, mid-, and long-disease duration. Method: Data from 168 individuals with EOPD who were categorized as having short (1-8 years, n = 44), mid (9-16 years, n = 88), and long disease durations (> 16 years, n = 36) were examined. Disease duration was defined as years from the onset of the first cardinal PD motor symptoms (self-reported and described in the clinical record) to the time of assessment. Patients in each disease duration group were classified according to whether they had normal cognition, PD-MCI, PD-D, and with cognitive impairment + severe depression. Cognitive performance on all tests and the frequency of cognitive statuses were compared between groups. Results: With the exception of the clock drawing test, no significant between-group differences were found in cognitive performance. There were no differences between the groups in terms of the frequency of normal cognition, PD-MCI, or PD-D. Conclusion: In our sample of patients with EOPD, no differences in cognitive performance or frequency of PD-MCI or PD-D were found between disease duration groups. These findings could indicate that MCI in EOPD remains stable and that PD-D is rare in patients under 70 years despite long disease duration, although further longitudinal studies should be carried out.

Keywords: Parkinson's disease. Mild cognitive impairment. Dementia. Cognition. Neuropsychological tests. Nervous system diseases.