Background. Previous longitudinal studies of the association between depression
and cognitive dysfunction have had relatively short follow-up periods. This
report presents a long-term study of the association between baseline syndromal
depression and cognitive outcome measured 9 to 12 years later.
Methods. Self-CARE (D) depression, cognitive function and pre-morbid intelligence
were recorded on 1083 subjects on entry to the Medical Research Council trial of
treatment of hypertension in older adults in 1983–5. In 1994–5, we aimed to
re-interview all survivors to assess cognitive function using the MMSE. We used
multivariate analysis to explore whether baseline depression predicted cognitive outcome
after this long follow-up period.
Results. Baseline depression was crudely associated with poorer cognitive outcome
at time 2. However, this long-term prospective association was no longer apparent
after adjusting for baseline cognitive performance, which was associated with baseline
depression and robustly predicted cognitive outcome at time 2. We found that gender
modified the association between depression and poorer cognitive outcome, so that
the association was statistically significant only among men.
Conclusion. Propensity for depression and failing cognition may have common
determinants that still need to be established by future neurobiological
investigations in conjunction with further long-term prospective epidemiological