This study by Willis et al. is highly informative about demographics and life expectancy in Parkinson's disease. The main findings are that life expectancy is shorter than might have been reported before, and that dementia is very common and is a significant contributor to mortality risk.

Previous estimates of dementia in PD have ranged from 25-75 percent (Buter et al., 2008; Emre, 2003; and others). The current report suggests it is closer to the 75 percent estimate. Also, this study now gives an estimate of how much dementia contributes to mortality. In fact, it appears that dementia is a leading contributor to mortality in PD. It has been reported by us and others that cognitive and functional decline are related in PD, and that cognitive decline is a risk factor for functional decline, but how it contributed to mortality had not been reported.

The study has a PD population that is older than other PD cohorts. The average onset is age 60, and the mean age is around 67. This...  Read more

This study by Willis et al. is highly informative about demographics and life expectancy in Parkinson's disease. The main findings are that life expectancy is shorter than might have been reported before, and that dementia is very common and is a significant contributor to mortality risk.

Previous estimates of dementia in PD have ranged from 25-75 percent (Buter et al., 2008; Emre, 2003; and others). The current report suggests it is closer to the 75 percent estimate. Also, this study now gives an estimate of how much dementia contributes to mortality. In fact, it appears that dementia is a leading contributor to mortality in PD. It has been reported by us and others that cognitive and functional decline are related in PD, and that cognitive decline is a risk factor for functional decline, but how it contributed to mortality had not been reported.

The study has a PD population that is older than other PD cohorts. The average onset is age 60, and the mean age is around 67. This cohort has a mean age (estimated, not reported) of around 75. The age might contribute to a shortened life expectancy and an increase risk of dementia. Parkinson's disease dementia (PDD) seems to have many etiologies. Our group previously reported that AD pathology represents about half of PDD. This report represents around two-thirds. AD is well known to be associated with an increased risk of mortality.

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