Not smoking, exercising regularly, having a high intake of plants and practicing stimulating intellectual activities are associated with a reduced risk of developing Alzheimer’s disease at older ages, by promoting cognitive reserve.
Human beings are distinguished from other animals by their intelligence and it is for this reason that we often tend to consider the brain as a separate organ, which has a particular status because of its capacity to generate phenomena as well. complex as thought, emotions, language and memory.
However, as with all organs in the human body, these advanced cognitive functions gradually decline during aging, a trend that accelerates after age 50 and significantly increases the risk of neurodegenerative diseases at older ages. From the age of 65, for example, the risk of developing Alzheimer’s disease doubles every 5 years, reaching almost 50% after the age of 85. These brain dysfunctions have a devastating impact, because they represent direct attacks on our intimate nature and our dignity, an intrusion into the very essence of what constitutes human existence.
Cognitive reserve
Although the increase in the incidence of neurodegenerative diseases has long been considered an inevitable consequence of the aging process, several studies carried out over the last decades have highlighted certain factors associated with the lifestyle of individuals which could make it possible to significantly reduce the risk of developing these diseases, in particular regular physical and intellectual activity (1).
A point common to several of these factors is to promote the formation of what is called a “cognitive reserve”, that is to say an increase in the number of interneuron connections which makes it possible to counteract the loss of neuronal function associated with normal aging. It has in fact been observed that the structural damage typical of Alzheimer’s disease (the appearance of deposits of beta-amyloid and tau proteins in particular) is detectable more than 20 years before the diagnosis of the disease (2).
Autopsy studies found that these deposits were also present in the brains of elderly people who had no apparent symptoms of Alzheimer’s until their death, suggesting that these people developed an Alzheimer’s disease during their lives. cognitive reserve which made it possible to establish neural circuits having the flexibility and adaptability necessary to compensate for the loss of defective neurons.
Anti-Alzheimer’s lifestyle
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A recent study clearly illustrates the crucial role of lifestyle habits in building this cognitive reserve (3). By closely following 586 people for several decades until their death (average age at death 91 years), researchers were able to collect information on several aspects of their lifestyle, regularly assess their cognitive function and analyze the presence of damage structural findings typical of dementias such as Alzheimer’s disease following an autopsy.
The impact of 5 major factors associated with lifestyle on the risk of developing Alzheimer’s disease was evaluated, namely 1) absence of smoking; 2) at least 150 minutes per week of physical activity; 3) a Mediterranean-type diet, rich in plant-based foods; 4) moderate alcohol consumption and 5) engaging in intellectually stimulating activities.
The researchers were able to demonstrate that a higher lifestyle score (i.e. greater adherence to the 5 parameters studied) was associated with better cognitive function, even as death approached. This association was observed even when several markers of Alzheimer’s disease were detected in the brains of the participants, suggesting that these lifestyle factors may allow the acquisition of a cognitive reserve capable of compensating for these molecular abnormalities and to maintain cognitive abilities in older adults.
As with all chronic diseases, Alzheimer’s disease is not an inevitable consequence of aging. In many cases, we can prevent this disease through the adoption of an overall healthy lifestyle which will optimize the function of neurons and counteract the deleterious effects of aging.
(1) Livingston G et coll. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. Lancet 2024; 404: 572-628.
(2) Jia J et coll. Biomarker changes during 20 years preceding Alzheimer’s disease. N. Engl. J. Med. 2024; 390: 712-722.
(3) Dhana K et coll. Healthy lifestyle and cognition in older adults with common neuropathologies of dementia. JAMA Neurol. 2024; 81: 233-239.
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