Early mild cognitive impairment in Parkinson’s increased demential risk

Developing persistent mild cognitive impairment soon after being diagnosed with Parkinson’s disease significantly increased the risk of subsequent dementia, according to a cohort study that examined the natural history of mild cognitive impairment in 178 patients over five years.

After the researchers controlled for age, sex, and education, patients who had persistent mild cognitive impairment (MCI) by one year after their Parkinson’s disease (PD) diagnosis had a 16.6-fold greater odds of subsequent dementia, compared with those who were cognitively normal (95 percent confidence interval, 5.1-54.7; P less than .001). Notably, early MCI significantly predicted dementia even if patients reverted to normal cognition with dopaminergic treatment, as reported by the Norwegian Centre for Movement Disorders at Stavanger (Norway) University Hospital. Early PD-MCI, regardless of persistence or reversion to normal cognition, has prognostic value for predicting dementia in patients with PD,” they concluded.

Their population-based study included white patients from Norway with a confirmed diagnosis of incident PD. Patients repeatedly underwent the Mini-Mental State Examination and a battery of tests of verbal memory, attention, executive functioning, and visuospatial skills.

At baseline, 20 percent of patients had MCI. Among those who did not, cumulative incidence rates of MCI were 10 percent at year 1, 23 percent at year 3, and 29 percent by the end of the study after five years of follow-up. In all, 59 percent of patients with persistent MCI by year 1 developed dementia, compared with seven percent of patients who retained normal cognition at 1 year. About one in four patients with MCI reverted to normal cognition by the end of the study, but they still faced a 10.7 fold greater odds of dementia at the 5-year follow-up, compared with cognitively normal patients (95 percent CI, 1.5-78.5; P=.02).