New evidence suggests Parkinson’s might start in the gut, not the brain
A new study adds to a growing body of research that suggests we might have been thinking about Parkinson’s disease wrong this whole time.
Instead of being isolated to the brain, new evidence in mice suggests that the condition might actually start in the gut. And it could explain some of the strange coincidences seen in the disease, such as why most Parkinson’s patients complain of constipation up to a decade before other symptoms arise.
Prediagnostic presentations of Parkinson’s disease in primary care: a case-control study
8166 individuals with and 46 755 individuals without Parkinson’s disease were included in the study. Apathy, REM sleep behaviour disorder, anosmia, hypersalivation, and cognitive decline were all reported in less than 1% of people per 1000 person-years and were excluded from further analyses. At 2 years before Parkinson’s disease diagnosis, the incidence of all studied prediagnostic features except neck pain or stiffness was higher in patients who went on to develop Parkinson’s disease (n=7232) than in controls (n=40 541). At 5 years before diagnosis, compared with controls (n=25 544), patients who went on to develop Parkinson’s disease (n=4769) had a higher incidence of tremor (RR 13·70, 95% CI 7·82–24·31), balance impairments (2·19, 1·09–4·16), constipation (2·24, 2·04–2·46), hypotension (3·23, 1·85–5·52), erectile dysfunction (1·30, 1·11–1·51), urinary dysfunction (1·96, 1·34–2·80), dizziness (1·99, 1·67–2·37), fatigue (1·56, 1·27–1·91), depression (1·76, 1·41–2·17), and anxiety (1·41, 1·09–1·79). At 10 years before diagnosis of Parkinson’s disease, the incidence of tremor (RR 7·59, 95% CI 1·11–44·83) and constipation (2·01, 1·62–2·49) was higher in those who went on to develop Parkinson’s disease (n=1680) than in controls (n=8305).
A range of prediagnostic features can be detected several years before diagnosis of Parkinson’s disease in primary care. These data can be incorporated into ongoing efforts to identify individuals at the earliest stages of the disease for inclusion in future trials and to help understand progression in the earliest phase of Parkinson’s disease.