ALZHEIMER´S DISEASE AND PHYSICAL ACTIVITY

                                                                    Evolution from healthy to diseased brain

The word “dementia” is used to talk about a set of neurodegenerative diseases, associated generally with aging. Because of the longer life expectancies, number of people suffering from dementia is rising consistently, with estimated numbers well over 100 million by the year 2050, making it a health priority for the World Health Organization.

Alzheimer´s disease (AD) accounts for 60-70% of dementia cases, and is characterised by a marked cognitive deterioration that affects memory, thinking and behaviour, and unaccountable to a normal ageing process. AD was long explained by the amyloid cascade hypothesis, as observations in brain tissue during post-mortem examination found accumulation of proteins, called amyloids which deposited intracellularly, affecting neuronal synapsis and causing neuronal death. Nowadays the explanation for AD onset is more complex, involving several pathogenic processes, which can be affected by genetic and environmental factors, and that goes beyond this entry.

In the development of AD have been distinguished three stages:

1/ Subjective Cognitive Decline (SCD): preclinical stage, without symptoms.

2/ Mild Cognitive Impairment (MCI): preclinical state, with some symptoms.

3/ Alzheimer´s Disease (AD): cognitive impairment, affecting daily activities.

Worthy to remark that not every individual in the SCD or MCI stages develops AD.

Physical activity (PA) has been considered beneficial on general health, as it decreases the risk of stroke and diabetes, among other diseases. A sedentary lifestyle has been associated with a higher risk of AD, so it was logical to study the effects of PA on it, as it would be an easier intervention than the pharmacological approach.

There are evidences that PA on the SCD stage may be a strategy to delay the AD progression, as it stimulates brain plasticity. Not every PA is the same, as it has been found that the PA related to work activities has not the same beneficial effects than the leisure PA. And for the leisure PA it was found that it offered more benefits when it was combined also with other mental and social activities, as it could be expected.

During lifetime it is obvious that generally there are different patterns regarding PA. Retirement should allow for more leisure time, although it is usually accompanied by a decrease in PA. Individuals with sedentary occupations otherwise generally increase their level of PA, especially if the economic status is good. PA at a higher age would be also beneficial in preventing, or delaying the effects of brain function decay associated with AD.

There have been found some genetic alterations that make people more susceptible of suffering AD (APOE4 for example). In these people is still unclear if a healthy lifestyle including PA could be enough to counteract the detrimental effects of these genetic alterations.

Until recently there were no many studies on PA at latter stages of AD. An article focusing on late running proved that, although the protein abnormal development was not altered in AD patients, it was able to improve memory performance and the agitation that also accompanies the illness.

As a conclusion we can say that PA (whether it is running or not), is useful in preventing and delaying AD at early stages, and also improves some of the symptoms in later stages.

 

Never is too late to exercise your body: it will also contribute to keep your mind and brain healthy.

 

Bibliography:

Late running is not too late against Alzheimer’s pathology

Herring A, Munster Y, Metzdorf J, Bolczek B, Krussel S, Krieter D, et al.

Neurobiol Dis 2016; 94:44-54.

 

Physical Activity and Alzheimer’s disease: A Systematic Review

Brini, S., Sohrabi, H.R., Peiffer, J.J. et al.

Sports Med (2018) 48: 29.

 

Physical Activity in Preventing Alzheimer’s disease and Cognitive Decline: A Narrative Review

Stephen, R., Hongisto, K., Solomon, A., Lönnroos, E.

The Journals of Gerontology: Series A, Volume 72, Issue 6, 1 June 2017, Pages 733–739 

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