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Editors

MiiaKivipelto
TiiaNgandu

Risk Factors for and Prevention of Memory Disorders

Risk factors for and prevention of memory disorders

  • The development of memory disorders, of which Alzheimer's disease (AD) is the most common, usually results from a combined effect of the environment and genes.
  • AD is a multifactorial disease with several cardiovascular and lifestyle-related risk factors, such as hypertension, elevated blood cholesterol levels, diabetes, alcohol consumption, smoking, lack of exercise and obesity. These can be influenced by lifestyle and by good treatment of risk factors.
  • It is estimated that at least 40% of memory disorders are associated with modifiable factors and could therefore possibly be prevented.

Risk factors and protective factors

  • The most important risk factor for memory disorders is age.
  • In addition, many risk factors associated with cardiovascular disease and lifestyle are important for memory disorders.
    • Some examples of factors increasing the risk of memory disorders:
      • cerebrovascular disease
      • hypertension in middle age
      • high cholesterol in middle age
      • obesity in middle age
      • diabetes and mild glucose metabolism disorders
      • heavy alcohol use
      • smoking
      • depression
      • head injuries.
    • The brain is protected by:
      • a high level of education
      • physical activity
      • an active lifestyle (active information processing and social interaction)
      • a healthy diet following dietary recommendations (preferring vegetable products, unsaturated fats, wholegrain products and fish)
      • group B vitamins (particularly folate and vitamin B12), antioxidants (vitamin E), vitamin D.
        • These data were obtained from population studies on nutrient intake and blood vitamin levels (not so much from studies on the use of vitamin products).
  • Physical activity and a healthy diet as such protect the brain but they may also lower the risk of memory disorder by affecting other risk factors.
  • The evidence on other risk factors is even more scanty: long-term stress, loneliness, various diseases, such as coronary artery disease, myocardial infarction, pulmonary diseases, sleep apnoea, certain infections and hearing loss, as well as air pollutants have been associated with an increased risk of memory disorders.
  • Antihypertensive medication is associated with a decreased risk.
  • Based on population studies, hormone replacement therapy, non-steroidal anti-inflammatory drugs (NSAIDs) and statins appear to reduce the risk of memory disorders, but in experimental setups no protective effect has been observed Prevention of Dementia by Statins.

The significance of risk factors over the lifespan

  • Changes in the brain associated with Alzheimer's disease start to develop even decades before the disease can be diagnosed.
  • The management of risk factors is important throughout the lifespan.
  • Hypertension, elevated cholesterol levels and obesity in middle age predispose to later memory disorders.
  • Studies in the elderly (> 75 years) have shown that a low blood pressure, low BMI and low cholesterol levels are associated with memory disorders ('reverse causality').
  • Diabetes increases the risk of memory disorders throughout the lifespan.
  • Physical activity reduces the risk in both middle and old age.
  • In the elderly, it is important to ensure sufficient nutrition and to prevent unintentional weight loss.

Memory disorder risk meter

  • This meter is intended for people from 39 to 64 years. It assesses the risk of memory disorder during the following 20 years.
  • The meter considers several risk factors for memory disorders, and the total score obtained shows whether the risk of developing a memory disorder is increased.

Memory disorder risk meter

Risk factorScore
Age
< 47 yrs
47-53 yrs
>53 yrs
0
3
4
Sex
Female
Male
0
1
Education
> 10 yrs
7-9 yrs
< 7 yrs
0
2
3
Systolic blood pressure
HASH(0x2fcf4d8) 140 mmHg
> 140 mmHg
0
2
Total cholesterol
HASH(0x2fcf4d8) 6.5 mmol/l
> 6.5 mmol/l
0
2
Body Mass Index (BMI)
HASH(0x2fcf4d8) 30 kg/m²
> 30 kg/m²
0
2
Physical activity
Active
Inactive
0
1
Total scoreRisk
0-5
6-7
8-9
10-11
12-15
1.0%
1.9%
4.2%
7.4%
16.4%

Combined effect of genetics and lifestyle

  • Carriers of the ε4 allele of the predisposing gene apolipoprotein E (APOE) have an about 2-3 times higher risk of developing AD.
  • About one in three Finns have the APOE ε4 gene.
  • Several lifestyle factors (such as smoking, insufficient physical activity, excessive alcohol consumption and high intake of saturated fatty acids) have been found to increase the risk of memory disorders and AD in these genetically susceptible people, particularly.
  • APOE ε4 carriers could perhaps benefit more from healthy habits than APOE ε4 negative people.

Prevention of memory disorders

  • Memory disorders can probably be prevented or their development delayed by influencing known risk factors.
  • The Finnish FINGER study is the first extensive long-term study worldwide set up to prevent memory disorders by influencing several risk factors simultaneously. The first results from the FINGER study show that by paying attention to multiple factors, such as a healthy diet, physical activity, memory training and control of cardiovascular risk factors, memory and cognitive functions can be improved in the elderly.

Key points

  • Detection and good treatment of all risk factors
  • Taking care of cardiac health
  • Regular physical activity
  • Following dietary recommendations
  • Training of information processing by doing various, preferably challenging, tasks; social activity.

Means

  • Individual tailoring (taking various diseases, functional restrictions and preferences into account)
  • Regular follow-up, encouraging attitude
  • Group activity providing motivation for lifestyle changes (nutritional groups, sports groups)
  • Long-term effective programme to achieve permanent results

    References

    • Ngandu T, Lehtisalo J, Solomon A et al. A 2 year multidomain intervention of diet, exercise, cognitive training, and vascular risk monitoring versus control to prevent cognitive decline in at-risk elderly people (FINGER): a randomised controlled trial. Lancet 2015;385(9984):2255-63. [PubMed]
    • Solomon A, Mangialasche F, Richard E et al. Advances in the prevention of Alzheimer's disease and dementia. J Intern Med 2014;275(3):229-50. [PubMed]
    • Kivipelto M, Ngandu T, Laatikainen T et al. Risk score for the prediction of dementia risk in 20 years among middle aged people: a longitudinal, population-based study. Lancet Neurol 2006;5(9):735-41. [PubMed]
    • Livingston G, Huntley J, Sommerlad A etl al. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Lancet 2020;396(10248):413-446. [PubMed]
    • World Health Organization. Risk reduction of cognitive decline and dementia: WHO guidelines. 2019 http://www.ncbi.nlm.nih.gov/books/NBK542796/