GLP-1 receptor genetics and Parkinson risk on GLP-1 drugs

Design

EHR-based new-user cohort with genetic proxy

Population

7,039 adults ≥50 with type 2 diabetes starting a GLP-1 receptor agonist

Primary outcome

Incident Parkinson disease and related disorders

Effect

HR 0.78 (95% CI 0.62–0.98); rate difference −1.36 per 1,000 person-years

A cohort study in Brain (5 October) used the US All of Us programme to follow 7,039 adults over 50 with type 2 diabetes who started a GLP-1 receptor agonist. A 15-variant genetic score predicting higher GLP-1 receptor expression was used to split them in half.

Over about four years, the high-score group had a lower rate of Parkinson disease and related disorders (hazard ratio 0.78), about 1.4 fewer cases per 1,000 person-years. There was no association with dementia.

The finding supports a biological basis for the mixed trial results of GLP-1 drugs in Parkinson disease, and suggests responders may be identifiable. It is hypothesis-generating and does not support prescribing these drugs to prevent Parkinson disease.

• Higher genetically predicted GLP-1 receptor expression was linked to less Parkinson disease on GLP-1 drugs
• No link was seen with dementia
• Do not prescribe GLP-1 drugs to prevent Parkinson disease on this evidence
• Relevant to future trial design rather than current practice

Why it matters

It offers an explanation for why GLP-1 trials in Parkinson disease have disagreed.

Don't overread it

Genetic association within an observational cohort; it does not show the drugs prevent Parkinson disease.

The statistics, in plain English

HR 0.78 (95% CI 0.62 to 0.98) is a modest association whose upper limit is close to 1. The absolute difference — about 1.4 cases per 1,000 people per year — is small.

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