Cognitive deficits are associated with a high risk for the development of incident parkinsonism in patients free from dementia, according to a study published in JAMA Neurology.
Investigators analyzed 7386 dementia- and parkinsonism-free patients from the Rotterdam Study to determine whether future cognitive deficits correlated with a heightened risk for neurologic movement disorders commonly experienced in Parkinson disease (PD). During a median follow-up of 8.3 years, incident parkinsonism developed in a total of 79 patients (1.1%). Of these, dementia developed in 24 (30.4%) and 57 (72.2%) were diagnosed with probable PD.
Patients with poor global cognition at baseline had a higher probability of receiving a diagnosis of incident parkinsonism than those with adequate or normal global cognition (hazard ratio [HR] 1.79; 95% CI, 1.37-2.33). The researchers found that this association continued beyond follow-up of 8 years as well as after removing patients from the analysis in whom dementia was diagnosed prior to parkinsonism onset (HR 1.59; 95% CI, 1.01-2.59 and HR 1.72; 95% CI, 1.28-2.27, respectively).
Additionally, a probable PD diagnosis and a combination of probable PD or dementia with Lewy bodies were both associated with poor cognitive function at baseline (HR 1.52; 95% CI, 1.10-2.08 and HR 1.59; 95% CI, 1.17-2.17, respectively).
The investigators noted that misclassification of parkinsonism diagnoses may have occurred for some patients in the cohort. Despite this potential limitation, the researchers observed similar findings when restricting the study to patients examined by geriatricians and neurologists only.
“Our data provide important insight into the association of cognitive functioning with incident parkinsonism in the general population,” they wrote, “and the findings suggest that cognitive dysfunction can be considered a sign of prodromal PD.”
Darweesh SKL, Wolters FJ, Postuma RB, et al. Association between poor cognitive functioning and risk of incident parkinsonism: the Rotterdam study [published online September 25, 2017]. JAMA Neurol. doi:10.1001/jamaneurol.2017.2248