24 July 2020

Evidence is in on ways to reduce Alzheimer’s risk

Clinical Neurology Smoking

Depression is one of 10 risk factors researchers have identified that can be targeted to reduce the risk of Alzheimer’s disease.

Fears of an oncoming wave of dementia have been escalating as our population ages – but more recent studies have suggested that the opposite may be happening.

There appears some evidence that rates of Alzheimer’s disease are declining, possibly due to healthier lifestyles and better education, say the authors of a recently published systematic review and meta-analysis.

An international group of researchers led by Professor Jin-Tai Yu at Fudan University in China, analysed 243 observational prospective studies and 152 randomised controlled trials to identify factors that had evidence of a protective effect against developing the disease.

The team said this was the most comprehensive and large-scale systematic review and meta-analysis for Alzheimer’s disease to date.

They identified 21 possible interventions that could reduce the risk of Alzheimer’s disease, 10 of which had strong supporting evidence:

  • Undertaking mentally stimulating activities, such as reading and playing chess
  • Avoiding daily stress
  • Avoiding diabetes with a healthier lifestyle
  • Managing and treat depression
  • Avoiding low BMI for those aged 65 and over
  • Avoiding head trauma
  • Managing and treat hypertension particularly in those aged under 65
  • Managing and treat orthostatic hypotension
  • Avoiding hyperhomocysteinaemia: regularly test serum homocysteine level, and treat hyperhomocysteinaemia with vitamin B and/or folic acid
  • Receiving as much education as possible in early life.

Nine suggestions had slightly weaker supporting evidence, but were nonetheless strongly recommended. These included:

  • Regularly exercising, especially for over-65s
  • Sleeping well
  • Quitting smoking and avoiding tobacco smoke in the environment
  • Maintaining a healthy BMI for under-65s
  • Avoiding losing weight in late life
  • Maintaining good heart health in older age including treating stroke risk factors such as atrial fibrillation
  • Ensuring adequate vitamin C intake, either in the diet or as supplements
  • Staying strong in late life – increasing frailty is linked with cognitive decline

The review did not find evidence supporting interventions such as oestrogen replacement therapy or acetylcholinesterase inhibitors.

“Nearly two-thirds of these suggestions target vascular risk factors and lifestyle, strengthening the importance of keeping a good vascular condition and maintaining a healthy lifestyle for preventing Alzheimer’s disease,” the authors wrote, adding the caveats that observational studies cannot prove causal relationships and RCTs are not always generalisable.

Evidence on the way social determinants and frailty affect the risk of Alzheimer’s disease is still lacking, they said.

Journal of Neurology, Neurosurgery & Psychiatry 2020, 20 July

COVID-19 live update