Dementia in Parkinson's Disease

Dementia, a known complication in Parkinson’s disease, is estimated to occur in 21 – 37% of patients. Can we predict who will be affected by this difficult complication? Like most of the symptoms of this disease, the only constant is its variability. Yet there are a few risk factors that may be used as predictors.

Age.Not only are those who develop Parkinson’s at an older age (over 60 years old) at a higher risk for cognitive decline but advanced age in general is a factor. In fact, current age is the most important determinant of dementia risk in those that are challenged by PD.

PIGD variant of Parkinson’s. The Postural instability and Gait Disturbance (PIGD) variant of Parkinson’s is characterized by significant balance problems and frequent falls as well as gait problems such as difficulty initiating movement and freezing. Those with this “type” of Parkinson’s are four times more likely to develop dementia compared to those with tremor-dominant disease.

Longer disease duration. The longer you have Parkinson’s disease, the increased chance for developing dementia.

More severe motor symptoms and disability. The combined risk of advanced age and severe disease is significant, one study showing a 12-fold increase in this group compared to younger patients with mild disease.

Male gender. Just as it is a risk factor for Parkinson’s itself, being male also puts you at increased risk for cognitive decline.

Poor response to L-dopa. Dementia seems to be more common in individuals whose symptoms don’t respond well to treatment with standard medications.

Other factors that may be associated with increased risk of developing dementia include:

Depression. Mood disorders are very common in Parkinson’s disease. Having a history of depression seems to be associated with cognitive decline.

REM Sleep Behavior Disorder. This sleep disorder is characterized by movements and dream related vocalizations during the REM stage of sleep.

Excessive daytime sleepiness.

The presence of confusion, visual hallucinations or psychosis as part of the symptoms experienced or their early development while on dopaminergic medication, can be a predictor of dementia in Parkinson’s disease.

Poor results on certain tests that look at learning, reasoning, verbal fluency and picture completion has been associated with future continued cognitive decline.

Having a sibling with Alzheimer’s Dementia increases risk for dementia in Parkinson’s.

Lower educational status.

So the answer to the question of whether or not you are at risk for dementia is that you can’t predict it with any certainty, much like any other aspect of Parkinson’s disease. There may be some factors that are associated with its development, some more significant than others but just because they exist does not mean that dementia is inevitable.

Truthfully no one really knows what the future holds and at some point in time, you have to let go of your fear of the future in order to begin living your present.