Parkinson's disease dementia: Diagnostic criteria and risk factor review.

Cognitive impairment in Parkinson's disease (PD) greatly affects the morbidity and mortality rates of the disease and can be present as mild executive dysfunction even in the early stages. In advanced PD, the prevalence of dementia (PDD) reaches more than 80%. The Movement Disorders Society (MDS) has proposed diagnostic criteria for PDD and Mild Cognitive Impairment (MCI) in PD, raising the sensibility and specificity of those diagnoses compared with DSM IV, for example. Cognition impairment is an important issue to determine in PD because of therapeutic, epidemiologic, and prognostic factors. These guidelines should be applied to a diagnosis of PD-MCI and PDD as soon as possible in order to provide a correct diagnosis. Another important topic to discuss regarding cognition in PD is which patient would be more likely to develop PDD. There are some risk factors for cognitive impairment in PD with cumulative risk. Important risk factors related to PDD are age, time of diagnosis, rigid-akinetic phenotype, severe impairment, impairment of semantic fluency, genetic factors, low education level, and postural instability. Recognizing them is also important for early diagnosis. We discuss the diagnostic criteria of PD cognitive impairment and some aspects of risk factors related to it in this review.