Progression to Cognitive Impairment in Parkinson Disease: A Gender Gap

“This study provides evidence for sex differences in the progression to cognitive impairment in PD, while specific cognitive features become more important indicators of progression with impending conversion to PD dementia,” wrote first author Brenna Cholerton, PhD, of Stanford University, and colleagues.¹

Most people with PD develop cognitive impairment at some point; one study suggests that over 80% of patients become affected over 20 years’ followup.² Yet progression of cognitive impairment varies widely across patients. Knowing specific patient factors that predict onset and progression may be important for caregivers and may help guide clinical management.

Participants were seen at clinics in the Udall Center Clinical Consortium (University of Washington, Oregon Health Sciences University, or Johns Hopkins University). They were assessed over time for 10 different cognitive variables involving mental processing speed, memory, and recall.

Men had almost 4.5 times increased risk for cognitive progression compared to women (OR 4.47, p=0.004), and they also progressed more rapidly (p=0.01).

Disease duration and verbal fluency were independent risk factors for cognitive progression in women.

Controlling vascular risk factors for dementia is also important, the authors noted. But the study had limited data on this variable. Further study is needed to determine how vascular factors contribute to onset and progression of cognitive impairment in PD.

• Study found that male sex is the primary predictive factor for transition from no cognitive impairment to cognitive impairment in PD.
• Cognitive impairment in men generally progresses faster than in women.
• Impaired processing speed and impaired working memory at baseline predict progression from mild cognitive impairment to dementia in PD.
• Knowing factors that predict cognitive progression in PD may be important for caregiver planning and clinical management.

REFERENCES
1. Cholerton B, Johnson CO, Fish B, et al. Sex differences in progression to mild cognitive impairment and dementia in Parkinson's disease. Parkinsonism Relat Disord. 2018;Feb 9. pii: S1353-8020(18)30043-9.
2. Hely MA, Reid WG, Adena MA, et al. The Sydney multicenter study of Parkinson's disease: the inevitability of dementia at 20 years. Mov Disord. 2008;23:837-844.