The tools of the trade: a state of the art "How to Assess Cognition" in the patient with Parkinson's disease.

Cognitive impairment in Parkinson's disease is heterogeneous both in severity and pattern and subject to influences both integral to and external to the disease. Diagnostic Criteria have been developed by the Movement Disorders Society that help to guide clinicians and researchers to an accurate diagnosis of Parkinson's disease - mild cognitive impairment or Parkinson's disease dementia. To operationalize these criteria, and to assess the pattern and severity of cognitive dysfunction we need: (1) Valid measures of cognitive abilities covering the major domains of cognition, (2) amethod to determine whether or not the performance represents a decline from a person's previous level of functioning, and (3) an assessment of how the individual's cognitive abilities enable (or disable) function in day to day activities. This paper will discuss the methods of assessment and the measures that can be used to make a comprehensive assessment of cognition in Parkinson's disease.