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Weight loss soon after Parkinson's disease diagnosis was tied to faster decline in global cognitive function and executive function, an observational study showed.

Parkinson's patients who lost more than 3% of their body weight in the first year after diagnosis had a faster decline in Montreal Cognitive Assessment (MoCA) scores than those who maintained their weight (β -0.19, 95% CI -0.28 to -0.10), reported Jin-Sun Jun, MD, of the Kangnam Sacred Heart Hospital in Seoul, Korea, and co-authors.

Likewise, early weight loss was tied to a steeper decline in semantic fluency (β -0.37, 95% CI -0.66 to -0.08) and phonemic fluency test scores (β -0.18, 95% CI -0.31 to -0.05), the researchers wrote in .

Parkinson's patients who gained more than 3% of their body weight in the first year after diagnosis had a slower decline in processing speed and attention scores (β 0.34, 95% CI 0.05-0.63), but not in MoCA scores.

Besides the defining motor symptoms of Parkinson's, cognitive impairment or other non-motor symptoms can emerge throughout the disease course.

"Although many epidemiologic studies report associations of both weight loss and weight gain with subsequent dementia in elderly populations, the evidence connecting early weight change and cognitive decline in patients with Parkinson's disease is still lacking," Jun told 乌鸦传媒.

"Our results provide evidence that early weight loss and weight gain have different implications for cognitive decline in patients with Parkinson's," Jun continued.

"The impact of early weight change on non-motor symptoms appeared to be specific to cognition," Jun noted. "Further studies are warranted to investigate whether targeted dietary interventions for weight loss slow cognitive decline in patients with Parkinson's disease."

Jun and colleagues studied 358 participants in the Parkinson's Progression Markers Initiative (), an ongoing multicenter biomarker study, following them for up to 8 years. After 8 years, 44% of the cohort remained in the study.

The PPMI recruited patients who were recently diagnosed with idiopathic Parkinson's disease but not treated for it. At baseline, participants had a stage of 2 or less and abnormal dopamine transporter imaging. Baseline mean age was 61.5 and age at Parkinson's onset was 59.6. Most participants (66%) were men.

Participants had annual assessments of neuropsychiatric, sleep-related, and autonomic symptoms, including MoCA and detailed neuropsychological tests, with more frequent evaluations in the early years after diagnosis.

The researchers grouped participants into three groups: weight-loss (98 people who lost 3% or more of their body weight in the year after diagnosis), weight-maintenance (201 people who stayed within 3% during that first year), and weight-gain (59 people who gained 3% or more of their body weight in the first year).

At 1 year, the weight-loss group lost an average of -7.1% of their body weight, while the weight-gain group gained 6.1%. There was no association between weight change and any other non-motor symptoms besides cognition.

The researchers also assessed 174 controls without Parkinson's and found that weight changes in these healthy older adults were not associated with longitudinal changes in cognition.

The rates of cognitive decline seen in this study appeared small, possibly because participants were relatively younger at baseline and highly educated, Jun and colleagues noted. The study could not determine whether effects of weight changes on cognition were similar in underweight or obese people, or whether weight changes were intentional, the team acknowledged.

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