First delirium episode in Parkinson's disease and parkinsonism: incidence, predictors, and outcomes.

To define the incidence, predictors and prognosis of the first hospital delirium episode in Parkinson's disease (PD) and atypical parkinsonism (AP), we identified the first hospital episode of delirium after diagnosis in the Parkinsonism Incidence in North-East Scotland (PINE) study, a prospective community-based incidence cohort of parkinsonism, using chart-based criteria to define delirium. Of 296 patients (189=PD, 107=AP [dementia with Lewy bodies, progressive supranuclear palsy, multiple system atrophy, vascular parkinsonism]), 152 developed delirium (PD = 98, AP = 54). Incidence of first hospital delirium episode per 100 person years was 8.1 (95% confidence interval [CI] 6.6-9.9) in PD and 18.5 (95% CI 13.9-24.7) in AP. Independent predictors of delirium were atypical parkinsonism (Hazard ratio [HR] vs PD = 2.83 [95% CI 1.60-5.03], age in PD but not in AP (HR for 10-year increase 2.29 [95% CI 1.74-3.02]), baseline MMSE (HR = 0.94 [95% CI 0.89-0.99]), APOE ε4 in PD (HR 2.16 [95% CI 1.15-4.08]), and MAPT H1/H1 in PD (HR 2.08 [95% CI 1.08-4.00]). Hazards of dementia and death after delirium vs before delirium were increased (dementia: HR = 6.93 [95% CI 4.18-11.48] in parkinsonism; death: HR = 3.76 [95% CI 2.65-5.35] in PD, 1.59 [95% CI 1.04-2.42] in AP). Delirium is a common non-motor feature of PD and AP and is associated with increased hazards of dementia and mortality. Whether interventions for early identification and treatment improve outcomes requires investigation.