Mild cognitive impairment is common in Parkinson's disease patients with normal Mini-Mental State Examination (MMSE) scores.
OBJECTIVE
Cognitive impairment occurs in the majority of Parkinson's disease (PD) patients, but little is known about detection of mild cognitive impairment (MCI) in this population. We report on the frequency and characteristics of cognitive deficits in PD patients with intact global cognition based on Mini-Mental State Examination (MMSE) performance.


METHODS
One hundred and six PD patients with normal age- and education-adjusted MMSE scores (mean [SD] score=29.1 [1.1]) were administered standardized neuropsychological tests assessing memory, executive function, and attention. Impairment on a cognitive domain was a low score (i.e., >or=1.5 SD below the published normative mean) on at least two measures or tests (for memory and executive abilities) or a single measure (for attention).


RESULTS
Mild cognitive impairment was found in 29.2% of PD patients, with 17.9% demonstrating single domain and 11.3% multiple domain impairment. Memory and attention impairment were most common (15.1% and 17.0%, respectively), followed by executive impairment (8.5%). Depending on the measure of disease severity chosen, increasing age and disease severity, anti-anxiety medication use, and a suggestion for increasing severity of daytime sleepiness were independent predictors of cognitive impairment.


CONCLUSIONS
Cognitive deficits are common in PD patients with "normal" cognition based on MMSE performance, suggesting that MCI is under-recognized in clinical practice due to routine use of insensitive screening instruments. In contrast with some previous reports, early memory impairment may be as common as either executive or attentional deficits in PD. In addition, psychiatric medication use and daytime sleepiness may be reversible or treatable contributors to cognitive impairment.
Mamikonyan
Eugenia
E
Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA.
Moberg
Paul J
PJ
Siderowf
Andrew
A
Duda
John E
JE
Have
Tom Ten
TT
Hurtig
Howard I
HI
Stern
Matthew B
MB
Weintraub
Daniel
D
D000368:Aged; D001288:Attention / Q000502:physiology; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008609:Mental Status Schedule; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications*; D011340:Problem Solving / Q000502:physiology