Selective memory impairment on an adapted Mini-Mental State Examination increases risk of future dementia.
OBJECTIVE
To determine whether selective memory impairment (SMI) on an adapted Mini-Mental State Examination (aMMSE) test increases risk of future dementia in a population-based survey of central Spain.


BACKGROUND
SMI is a strong predictor of dementia in the elderly. However, most approaches have used extensive memory batteries, which are not always suitable for screening purposes.


METHODS
The basal cohort consisted of 2982 poorly educated individuals aged 65 or over. Dementia, stroke and parkinsonism cases were previously excluded. At entry, participants received a structured interview including an aMMSE. Two groups were created according to basal cognitive performance, namely: (1) aMMSE > 23 and no word remembered on the aMMSE delayed-recall task (SMI group); and (2) aMMSE > 23 and at least one word remembered on the delayed-recall task (control group). In a three-year follow-up wave, conversion rate to dementia was calculated and logistic regression was performed.


RESULTS
Of a total of 2507 subjects who completed the two evaluations, 280 qualified for SMI at entry. In the SMI group, 25 subjects (8.9%) developed dementia vs 26 subjects (1.2%) in the control group. Taking the two groups together, and once demographic and medical variables had been controlled, a low delayed-recall score increased dementia conversion rate (OR 0.47, 95% CI 0.34-0.64). Alzheimer's disease was the main cause of dementia (79.8%).


CONCLUSIONS
Memory impairment is a risk factor for future dementia in the neurologically-healthy elderly. This can be observed in a subgroup of subjects with SMI defined on the aMMSE delayed-recall subscore. Some other measurements should be added to the SMI construct to improve its predictive validity.
Olazarán
J
J
Neurology Clinic, CEP Hermanos Sangro, Madrid, Spain. javier@mariawolff.es
Trincado
R
R
Bermejo
F
F
Benito-León
J
J
Díaz
J
J
Vega
S
S
D000368:Aged; D000544:Alzheimer Disease / Q000209:etiology / Q000523:psychology; D003071:Cognition; D003072:Cognition Disorders / Q000150:complications / Q000523:psychology; D015331:Cohort Studies; D003704:Dementia / Q000209:etiology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000150:complications* / Q000523:psychology; D011159:Population Surveillance / Q000379:methods; D011379:Prognosis; D011581:Psychological Tests; D012307:Risk Factors