Objective, To test the hypothesis that aspirin and non-steroidal anti-
inflammatory drugs (NSAIDs) may prevent dementia or cognitive impairme
nt. Design. A two-wave longitudinal study over 3.6 years. Setting. A c
ommunity survey of elderly persons living in Canberra, Australia. Part
icipants. There were 1045 elderly persons aged 70 at the start of the
study; cognitive assessment was obtained at both waves on 588. Main ou
tcome measures, Cognitive functioning was measured using the Mini-Ment
al State Examination, an episodic memory test, a test of mental speed
and the National Adult Reading Test, Dementia was assessed using the C
anberra Interview for the Elderly. Results, On cross-sectional data, t
hose who had been taking NSAIDs or aspirin performed no better on the
cognitive tests after account had been taken of other confounding vari
ables. There was no interaction with apolipoprotein E genotype. On lon
gitudinal data, no difference was found between NSAID or aspirin users
and controls, either in cognitive decline or incidence of dementia. C
onclusions, The results do not support the hypothesis that aspirin or
NSAIDs have a protective effect, but it remains possible that various
sources of measurement error may have attenuated an effect of clinical
significance from either type of drug. Conclusive evidence can be obt
ained only by a prospective trial, (C) 1997 John Wiley & Sons, Ltd.