Three new factors added to dementia risk timeline

Morgan Liotta

31/07/2020 3:11:32 PM

Excessive alcohol consumption, traumatic brain injury and air pollution have been added to existing risk factors.

Two middle-aged men toasting glasses of red wine.
Excessive alcohol consumption in mid-life has been shown to increase a person’s dementia risk.

Almost half (40%) of dementia cases could be prevented or delayed by targeting 12 lifestyle risk factors, according to latest data collated by Australian and international experts.
Published in The Lancet, the new research builds on existing 2017 Lancet Commission studies that identify nine potentially modifiable risk factors for developing dementia:

  • Hypertension
  • Hearing impairment
  • Smoking
  • Obesity
  • Depression
  • Physical inactivity
  • Limited education
  • Diabetes
  • Low social contact
Researchers have now added three more to the list:
  • Head injuries in mid-life
  • Excessive alcohol consumption in mid-life
  • Exposure to air pollution later in life
These three factors combined account for around 6% of dementia cases, with an estimated 3% of cases attributable to head injuries in mid-life, 1% of cases to excessive alcohol consumption (of more than 21 units per week) in mid-life, and 2% to exposure to air pollution in later life.
The original nine risk factors combined are estimated to contribute to 35% of all dementia cases.
These findings are based on systematic reviews, meta-analyses and individual studies to produce a framework of evidence on dementia risk in various countries, risks and protective factors, detection, multimorbidity and interventions for people with dementia.
However, as the researchers note that nearly all of the evidence for dementia is from studies in high-income countries, risks might differ for low-income and middle-income countries. For example, in China they might account for 40% of cases, 41% in India and 56% in Latin America.
The researchers also cautioned that these estimates could be higher because the three new risk factors were not included in previous studies.
There are around 50 million people living with dementia globally, with approximately 10 million new cases every year.
Despite figures expected to rise particularly in low- and middle-income countries, the proportion of older people with dementia has fallen, according to the new research.
These findings are likely due to improvements in education, nutrition, healthcare, and lifestyle changes, demonstrating the possibility of reducing dementia through preventive measures.
As part of a life-course model of dementia prevention, researchers have identified the following lifestyle interventions as key to addressing dementia risk.
  • Aim to maintain systolic blood pressure of 130 mm Hg or less in mid-life from around age 40 years
  • Encourage use of hearing aids for hearing loss and reduce hearing loss by protecting ears from high-noise levels
  • Reduce exposure to air pollution and second-hand tobacco smoke
  • Prevent head injury (particularly by targeting high-risk occupations and transport)
  • Prevent alcohol misuse and limit drinking to less than 21 units per week
  • Prevent smoking uptake and support individuals to quit smoking
  • Provide all children with primary and secondary education
  • Lead an active life where possible
  • Prevent and reduce rates of obesity and diabetes
These interventions may require modification to best support cultural and environmental diversity, lead author Professor Gill Livingston from University College London said, but are likely to have the biggest impact on those who are disproportionately affected by dementia risk factors, like those in low- and middle-income countries and vulnerable populations.
‘Our report shows that it is within the power of policymakers and individuals to prevent and delay a significant proportion of dementia, with opportunities to make an impact at each stage of a person’s life,’ Professor Livingston said.
‘Our new life-course model and evidence synthesis has paramount worldwide policy implications. It is never too early and never too late in the life course for dementia prevention.
‘We can reduce risks by creating active and healthy environments for communities, where physical activity is the norm, better diet is accessible for all, and exposure to excessive alcohol is minimised.’
RACGP resources
  • SNAP guide – provides guidance for general practice teams to work with patients on the lifestyle risk factors of smoking, nutrition, alcohol and physical activity (SNAP)
  • Red Book – provides guidance for general practice teams on opportunistic and proactive preventive care, including a chapter on dementia risk assessment
  • Silver Book – comprehensive aged care clinical guide, including sections on dementia screening and management
  • National guide to a preventive health assessment for Aboriginal and Torres Strait Islander peopledementia risk assessment included in the health of older people chapter
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