Cognitive assessment of a representative community population with Parkinson's disease (PD) using the Cambridge Cognitive Assessment-Revised (CAMCOG-R)

Background: cognitive decline is well recognised in Parkinson's disease (PD) but the best cognitive assessment tool for use in such patients remains unclear. The 30-point Mini-Mental State Examination (MMSE), while quick and straightforward to use, fails to cover a full range of cognitive domains and is recognised to have a ceiling effect. The Cambridge Cognitive Assessment-Revised (CAMCOG-R) is a cognitive screening tool allowing the assessment of a number of different domains of cognition. It has not previously been used specifically on PD subjects. Methods: a prevalent community population of 135 PD patients were assessed cognitively using the MMSE. Those scoring 25 or above on the MMSE were subsequently further assessed using CAMCOG-R. Demographic and disease factors including disease duration, symptom severity, anxiety, depression and the presence of hallucinations were recorded for each participant. Results: 31/135 (23%) demonstrated cognitive impairment on the MMSE (score < 25). Ninety-four of the remaining group (10 were excluded) achieved a median total CAMCOG-R score of 89/104. The results were widely distributed. The subjects scored particularly highly in the cognitive domains of orientation, comprehension and perception but relatively poorly at memory and abstract thinking. Significantly poorer scores (P< 0.05) were seen throughout the cognitive domains with increasing age, increasing PD symptom severity and increasing disease duration, but not with the presence of anxiety, depression or hallucinations in the subjects. Discussion: CAMCOG-R was found to be a viable and useful cognitive screening tool for use in PD. A wide range of cognitive ability was demonstrated in subjects who had been assessed previously by the MMSE as not having significant cognitive impairment. The group performed worse in certain cognitive domains than others and those who were older, with more severe PD symptoms and with symptoms for longer, scored less well.