Population aging is bringing about a substantial increase in the prevalence of neurocognitive disorders. Current projections estimate that, by 2050, more that 130 million people will be affected by dementia worldwide. As experts assemble to devise strategies to face this incoming challenge, one conclusion stands out: prevention is crucial.
The goal of prevention is obvious: to promote good health and take action before disease onset, thereby reducing the incidence of disease. And this is obviously better than having to manage a disease and its complications, and losing quality of life – “prevention is better than cure.”
But in order for preventive behaviors to be acquired, knowledge is essential – knowledge of modifiable risk factors and preemptive actions that can be adopted, and knowledge of how effective they really are. Studies addressing the benefit of lifestyle interventions for the prevention of dementia have identified numerous modifiable risk and protective factors and have shown that change can indeed be beneficial.
Modifiable risk factors for cognitive impairment include lifestyle factors such as smoking, high alcohol intake, diet (saturated fats, sugar, processed foods), and poor physical activity; these then manifest in other risk factors that are already a consequence of inadequate lifestyle options, namely vascular and metabolic diseases (cerebrovascular and cardiovascular diseases, diabetes, hypertension, overweight and obesity, high cholesterol). In the end, it all builds up to speed up cognitive decline.
Protective factors include opposite lifestyle choices, such as quitting smoking, moderate alcohol intake, healthier diet (Mediterranean diet, polyunsaturated fatty acids and fish-related fats, vitamins B6 and B12, folate, antioxidant vitamins (A, C and E), vitamin D, physical activity, and mentally stimulating activity.
Still, cognitive disorders are complex, multifactorial conditions – even if you lead the healthiest life, dementia may still strike you. But this should not be an excuse to let go because research shows is that preventive behaviors shift the odds in your favor.
An important aspect of behavioral change is that it should be integrative. Single-domain interventions provide some benefit: physical activity and cognitive training have been positively associated with cognitive performance in multiple studies; also, a recent meta-analysis showed that an increased consumption of fruit and vegetables reduces the risk of cognitive impairment and dementia. But multi-domain interventions, in which multiple risk factors are targeted simultaneously are more likely to deliver better results.
For example, a 2015 Finnish study assessed the effect of a 2-year multimodal intervention in adults aged 60-77 years at risk of cognitive decline but without pronounced cognitive impairment. Four intervention targets were included: diet, exercise, cognitive training, and vascular risk. The program’s design included a diet with high consumption of fruit and vegetables, consumption of wholegrain cereal products and low-fat milk and meat products, low sucrose intake, use of vegetable margarine and rapeseed oil instead of butter, and fish consumption at least two portions per week.
The physical exercise training program included progressive muscle strength training, aerobic exercise, and exercises to improve postural balance. Cognitive training consisted of computer-based training targeting executive processes, working memory, episodic memory, and mental speed. Metabolic and vascular risk factors were monitored throughout the study. Social activities were also stimulated through the numerous group meetings of all intervention components.
The study showed that simultaneous changes in multiple risk factors, even of small magnitude, had beneficial effects on the risk of cognitive decline, on overall cognition, complex memory tasks, executive functioning and processing speed, and on also BMI, dietary habits, and physical activity.
But a timely prevention seems fundamental – these lifestyle interventions may not be as effective once cognitive impairment is manifest. A recent study evaluated the impact of a 3-year omega-3 fatty acid supplementation with or without multi-domain lifestyle interventions on cognitive function in adults aged 70 years or older. These adults already had symptoms of cognitive impairment: either memory complaints, limitations in one instrumental daily living activity, or slow gait speed. The multi-domain intervention included cognitive training, physical activity, nutrition, and management of cardiovascular risk factors.
In this case, neither the omega-3 supplementation alone, nor the combination with the lifestyle interventions were able to reduce cognitive decline. Also, the adherence to lifestyle interventions over time was lower in this study when compared to other studies with younger seniors, with no clinical manifestations of dementia onset. But still, those with increased risk of dementia were the ones who benefited the most.
Early prevention is probably the best strategy. Instead of trying to prevent dementia later in life, focusing on preventing earlier, milder, and more common forms of cognitive impairment may be a better strategy that may end up also preventing cardiovascular and metabolic diseases and, ultimately, dementia. Because they’re all fruits from the same tree.
Andrieu S, et al (2017). Effect of long-term omega 3 polyunsaturated fatty acid supplementation with or without multidomain intervention on cognitive function in elderly adults with memory complaints (MAPT): a randomised, placebo-controlled trial. Lancet Neurol, 16(5):377-389. doi: 10.1016/S1474-4422(17)30040-6
Jiang X, et al (2017). Increased Consumption of Fruit and Vegetables Is Related to a Reduced Risk of Cognitive Impairment and Dementia: Meta-Analysis. Front Aging Neurosci, 9:18. doi: 10.3389/fnagi.2017.00018
Kivipelto M, et al (2017). Can lifestyle changes prevent cognitive impairment? Lancet Neurol, 16(5):338-339. doi: 10.1016/S1474-4422(17)30080-7
Ngandu T, et al (2015). 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, 385(9984):2255-63. doi: 10.1016/S0140-6736(15)60461-5
Shah H, et al (2016). Research priorities to reduce the global burden of dementia by 2025. Lancet Neurol, 15(12):1285-1294. doi: 10.1016/S1474-4422(16)30235-6
Solomon A, et al (2016). Advances in the prevention of Alzheimer’s disease and dementia. J Intern Med, 275(3):229-50. doi: 10.1111/joim.12178
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