Objective The aim of this study was to examine whether low-dose acetylsalicylic acid (ASA) influences the rate of cognitive change in elderly women.

Design Prospective, population-based cohort study.

Setting The city of Gothenburg, Sweden, including those living in private households as well as in residential care.

Participants The sample was derived from the Prospective Population Study of Women and from the H70 Birth Cohort Study in Gothenburg, Sweden. Both samples were obtained from the Swedish Population Register, based on birth date, and included 789 (response rate 71%) women aged 70–92 years. After the exclusion of individuals with dementia and users of warfarin, clopidogrel or heparin at baseline, 681 women were examined. Among all participants, 95.4% (N=601) had a high cardiovascular risk (CVD), defined as 10% or higher 10-year risk of any CVD event according to the Framingham heart study and 129 used low-dose ASA (75–160 mg daily) at baseline. After 5 years a follow-up was completed by 489 women.

Primary outcome and secondary outcome measures Cognitive decline and dementia incidence in relation to the use of low-dose ASA and cardiovascular risk factors. Cognition was measured using the Mini Mental State Examination (MMSE), word fluency, naming ability and memory word tests. Dementia was diagnosed according to the DSM-III-R criterion. As secondary outcome incidence of stroke and peptic ulcer in relation to low-dose ASA use was studied.

Results Women on regular low-dose ASA declined less on MMSE at follow-up than those not on ASA. This difference was even more pronounced in those who had ASA at both examinations (p=0.004 compared with never users; n=66 vs n=338). All other cognitive tests showed the same trends. There were no differences between the groups regarding short-term risk for dementia (N=41).

Conclusion Low-dose ASA treatment may have a neuroprotective effect in elderly women at high cardiovascular risk.