Title:
Cognitive impairment in Parkinson disease: impact on quality of life, disability, and caregiver burden.

Abstract:
To compare quality of life, level of disability, and caregiver burden in 3 groups of people with Parkinson disease (PD): those with mild cognitive impairment (PD-MCI), those with dementia (PDD), and those with no cognitive impairment (PD-NC).
Although the cognitive profile of those with PD-MCI and PDD has been well described, little is known about the personal and clinical impact of cognitive impairment and its impact on caregivers.
Quality of life and disability were measured in 3 groups of participants with PD (PD-NC, n=54; PD-MCI, n=48; and PDD, n=25). The PD-MCI group was classified using Movement Disorder Society Task Force consensus criteria. Caregivers (n=102) in the 3 groups were assessed using the Zarit Burden Inventory.
Both quality of life and caregiver burden were similar in the 2 groups without dementia but were significantly different in those with PDD. In contrast, global disability was progressively greater as cognition declined across the 3 PD groups: PD-NC<PD-MCI<PDD and on the Activities of Daily Living scale a step up in impairment was seen with the presence of any cognitive impairment.
The presence of dementia significantly increases caregiver burden and decreases quality of life. However, even mild levels of cognitive impairment increase disability and overall functional impairment progresses in tandem with cognitive decline.