The landmark FINGER trial (Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability), published in The Lancet in 2015, was the first large randomized controlled trial to show that a multi-domain lifestyle intervention - diet, exercise, cognitive training, and vascular risk monitoring - produced measurable improvements in cognition in at-risk older adults compared to a control group.
The 2024 Lancet Commission on dementia prevention identified 14 modifiable risk factors that together account for nearly half of dementia cases worldwide. The biggest contributors are hearing loss in midlife, less education in early life, high LDL cholesterol, smoking, social isolation, depression, and physical inactivity - every one of which is addressable.
Sleep is the single most under-rated lever. During slow-wave sleep, the glymphatic system clears beta-amyloid and tau - the same proteins implicated in Alzheimer's disease - at roughly twice the daytime rate, according to research from the University of Rochester Medical Center (Nedergaard lab, Science 2013). Chronic sleep restriction below 6 hours is associated with measurable next-day cognitive decline equivalent to mild intoxication.
Aerobic exercise is the most reliably brain-protective behavior we have studied. Mayo Clinic and Harvard T.H. Chan School of Public Health both cite ≥150 minutes/week of moderate cardiovascular activity as the threshold associated with reduced dementia risk and increased hippocampal volume - the brain region most central to memory formation.