For patients with Parkinson disease, 9 risk factors were identified that could increase the risk for cognitive impairment, according to a study published in Movement Disorders.

Researchers completed a comprehensive systematic review and a meta-analysis using PubMed and the Cochrane Library to identify prospective cohort studies to recognize potentially modifiable risk factors that lead to cognitive impairment in patients with Parkinson disease. All studies included provided either odds ratio or relative risk (RR) calculations of potential risk factors.

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Of the studies that met inclusion criteria for the meta-analysis, there were 11,761 patients (48.29% men; mean age, 68.31 years; mean follow-up time, 4.07 years). Postural-instability-gait disorder (RR, 3.76; 95% CI, 1.36-10.40; P <.01), hallucinations (RR, 3.09; 95% CI, 1.61-5.93; P =.08) and orthostatic hypotension (RR, 2.98; 95% CI, 1.41-6.28; P =.21) were motor subtypes of Parkinson disease associated with increased risk for cognitive impairment.

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Alcohol consumption (RR, 1.32; 95% CI, 1.15-1.52; P =.58) and ever being a smoker (RR, 1.31; 95% CI, 1.14-1.50; P =.38) were lifestyle risk factors associated with increased risk for cognitive impairment. Cerebrovascular disease (RR, 1.52; 95% CI, 1.01-2.28; P <.01), diabetes (RR, 1.47; 95% CI, 1.13-1.92; P =.47), obesity (RR, 1.38; 95% CI, 1.15-1.65; P =.58), and cardiac disease (RR, 1.35; 95% CI, 1.17-1.5; P =.47) were comorbidities associated with increased risk for cognitive impairment. In the systematic review, these 9 risk factors and 1 protective factor — physical activity — were identified to have an association with the risk for cognitive impairment in patients with Parkinson disease.

Limitations of this study include the inability to prove causality due to using observational cohort studies, the lack of consistent risk factors involved across all the included studies, and heterogeneity of patients and tests.

The researchers concluded that “effective interventions in [Parkinson disease] symptoms, comorbidities, and lifestyle may be promising to reduce [Parkinson disease with cognitive impairment] risk.”


Guo Y, Xu W, Liu FT, et al. Modifiable risk factors for cognitive impairment in Parkinson’s disease: a systematic review and meta-analysis of prospective cohort studies [published on March 14, 2019]. Mov Disord. doi: 10.1002/mds.27665