Potential increase in PD incidence reported
medwireNews: A study in Minnesota, USA, has found an increase in the incidence of parkinsonism and Parkinson’s disease (PD) over the past 30 years that may be related to the dramatic reduction in smoking behaviour in the second half of the 20th century or other lifestyle or environmental changes.
“If the trend of increasing rates is genuine and can be replicated in other populations, it has major implications for etiologic research and for public health”, say Walter Rocca (Mayo Clinic, Rochester) and colleagues in JAMA Internal Medicine.
The study of 906 patients with parkinsonism and 464 with PD showed a 24% increase per decade in age-adjusted PD incidence among men, from 18.2 per 100,000 person–years in 1976–1985 to 30.4 per 100,000 person–years in 1996–2005. This increase was predominantly due to a 35% rise per decade among men older than 70 years of age, compared with 5% among younger men. Similar trends, albeit of smaller increases, were also seen for parkinsonism symptoms. For women, however, the rate of PD and parkinsonism remained largely stable.
Birth cohort analysis also indicated an increased risk of PD for men born between 1915 and 1924, compared with during other periods, suggesting the possible effects of early life exposures at this time.
“The epidemiologic observation that cigarette smoking is associated with lower PD risk is robust but the debate over whether the association is causal seems never to be resolved”, says editorialist Honglei Chen (National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA).
“However, results of the [current] study and a similar previous analysis may offer indirect support for causality”.
By Lucy Piper
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