The MRC Cognitive Function and Ageing Study (CFAS) was a large-scale, long-term investigation into the health and cognitive functioning of older adults. The study, led by Professor Carol Brayne, undertook interviews in populations aged 65+ years in six cities in England and Wales between 1989–1994 (CFAS I), and two decades later between 2008–2011 (CFASII). Initially focused on understanding how cognitive decline and dementia affect the ageing population, CFAS expanded its aims to explore various aspects, including descriptive epidemiology, neuropathology, policy, molecular epidemiology, and ethics.

Key findings and impact:

• The prevalence of dementia. Before CFAS there were no population figures which could be confidently applied nationally and to specific geographical areas. The research showed that dementia was common and more prevalent than previously thought affecting 6.6% of those over 65 and rising sharply to 25.3% among the 85-89 age group.
• However, the second stage of CFAS provided compelling evidence of a reduction in the prevalence of dementia in the older population over two decades.
• The cost of care. The study demonstrated the high cost of informal care in supporting people with dementia, which was much greater than previously estimated.
• Risk factors for dementia CFAS demonstrated a relationship between demographic and lifestyle factors and risk of cognitive impairment, including age, stroke and Parkinson's disease, and the protective effect of higher education and of self-reported `good' or `excellent' health.
• Neuropathology insights. CFAS has been a major contributor to a unique population representative brain resource, with the first brain donated in 1993 and more than 500 donations of participant’s brains after death. This repository has enabled researchers to explore the complex determinants of dementia and cognitive decline more deeply.