Life long changes in cognitive ability are associated with prescribed medications in old age

To determine the association between prescribed medication and life long changes in cognitive ability.

Retrospective cohort study.

Community residents of a largely urban region of South East Scotland.

Four hundred and seventy-eight survivors of the 1932 Scottish Mental Health Survey (n=87,498) without dementia.

The Moray House Test (MHT) of intelligence administered at age 11 and age 80 years. Hospital Anxiety and Depression Scale (HADS) score, history of disease and current prescribed medications age 80 years.

After adjusting for sex, neuroactive drugs had a detrimental effect on life long cognitive change age (F=12.2, p=0.001, partial eta-squared=0.026), statins a beneficial effect (F=5.78, p=0.017, partial eta-squared=0.013) and polypharmacy a detrimental effect (F=6.46, p=0.011, partial eta-squared=0.014). In the optimal model estimated marginal means revealed: a relative improvement for statin users, IQ age 11=93.2 (95% CI 87.9-98.4) and age 80=100.6 (95% CI 95.3-105.9); compared with non-users, IQ age 11=100.9 (95% CI 99.4-102.3) and age 80=100.0 (95% CI 98.6-101.5).

Clinically, the degree to which drugs impair cognition in relatively fit, older people may not be apparent. However, in population terms, medication use, particularly polypharmacy, is important. Statins, used as currently indicated for cardiovascular disease, appear promising in ameliorating cognitive decline in older people. However, firm recommendation of their use should await the outcome of ongoing randomised clinical trials.