Cognitive decline is faster in Lewy body variant than in Alzheimer's disease.
OBJECTIVE
To quantify the rate of cognitive decline on the Mini-Mental State Examination (MMSE) in autopsy-diagnosed Lewy body variant (LBV) of Alzheimer's disease (AD) cases. We hypothesized that LBV patients would have a faster cognitive decline and shorter survival compared with patients with pure AD.


BACKGROUND
Prior reports have shown extrapyramidal signs to be associated with a poorer prognosis in AD. It has been suggested that LBV is often characterized by a rapidly progressive course. Few data are available regarding the rate of cognitive decline in autopsy-confirmed LBV dementia cases.


METHODS
We searched the databases of the University of California-San Diego Alzheimer's Disease Research Center and the Consortium to Establish a Registry in Alzheimer's Disease (CERAD) for dementia cases with 1) an autopsy diagnosis of definite or probable AD (CERAD criteria) with concomitant Lewy bodies and 2) longitudinal MMSE assessments. This resulted in a series of 40 LBV cases and 148 AD cases without Lewy bodies, with comparable baseline MMSE scores, age, and education. The rate of cognitive decline was calculated as the baseline MMSE -- final MMSE. Methods were devised to reduce floor effects on the MMSE.


RESULTS
The average rate of cognitive decline was -5.8 +/- 4.5 points/y in LBV and -4.1 +/- 3.0 points/y in AD (t-test, p < 0.01). The LBV group declined a similar amount on the MMSE (means, -10.0 versus -9.6 points) over a significantly shorter time interval (1.9 versus 2.7 years; p = 0.005) than did AD patients. At baseline, the mean MMSE scores were nearly identical (18.2 in LBV; 17.8 in AD), but on follow-up examinations approximately 1, 2, and 3 years later, there were intergroup mean differences of 1.8 points (two-tailed p = 0.19), 4.2 points (p = 0.04), and 5.6 points (p = 0.03), respectively. The LBV cases had shorter survival time from the onset of cognitive symptoms (7.7 +/- 3.0 years versus 9.3 +/- 3.5 years; p = 0.007) and a shorter mean survival after entry/baseline, which was of marginal significance (3.6 versus 4.1 years; p = 0.11).


CONCLUSIONS
This study demonstrates that LBV is characterized by a faster cognitive decline and accelerated mortality compared with AD.
Olichney
J M
JM
Department of Neurosciences, University of California, San Diego and San Diego Veteran's Affairs Medical Center, 92161, USA.
Galasko
D
D
Salmon
D P
DP
Hofstetter
C R
CR
Hansen
L A
LA
Katzman
R
R
Thal
L J
LJ
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000523:psychology*; D003072:Cognition Disorders / Q000209:etiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000523:psychology*; D011379:Prognosis