The likelihood of cognitive decline is higher in patients who lose weight after receiving a diagnosis of Parkinson’s disease, suggests a new study published in the journal Neurology.¹

Patients diagnosed with early Parkinson’s disease two years (average) back and were not yet taking anti-Parkinson drugs were included in this observational study. These patients were a part of the Parkinson’s Progression Markers Initiative cohort. Their average age was 61 years. 174 individuals who did not have Parkinson’s disease acted as controls. Cognitive assessment was done at baseline with the Montreal Cognitive Assessment (MoCA) and other neuropsychological tests and then annually for up to 8 years. Patients were also simultaneously evaluated for other non-motor symptoms including autonomic symptoms, neuropsychiatric symptoms and sleep disorders.

The 358 patients included in the study were categorized into three groups based on alterations in weight: weight gain (increase of >3%), weight loss (decrease of >3% body weight during the first year) and weight maintenance (within ±3%). Fifty-nine participants had weight gain, 98 lost weight, while 201 study subjects maintained their weight during the course of the study.

The MoCA scores declined rapidly among those who lost weight compared to patients who continued to maintain their weight. A sharp decline was noted specifically for semantic fluency test scores and MoCA phonemic fluency scores. The Letter-Number Sequencing score (which measures working memory capacity) also dropped. On the other hand, the decline in the Symbol-Digit Modalities Test scores (to assess neurological dysfunction) was slower among patients who gained weight. No such association between change in weight and other non-motor symptoms.

These findings suggest that decline in global cognitive function and executive function in patients with Parkinson’s disease was faster among those who experienced early weight loss. The study however does not establish weight loss as a cause of cognitive impairment. Early weight loss, therefore may be a sign of patients at risk of cognitive decline. The authors have called for further studies to investigate if preventing weight loss could slow down the process of cognitive decline in patients with early Parkinson’s disease.

Reference

1. Kim R, et al. Association of early weight change with cognitive decline in patients with Parkinson disease. Neurology. 2022. DOI: 10.1212/WNL.0000000000201404.