Cognitive reserve: what is it and how does it protect us from dementia?

When ill, the brain is able to optimize its functioning to mitigate symptoms.

Brain damage often causes alterations in cognition that manifest themselves in many different ways. Cognitive reserve, which protects us from these types of symptoms, is defined as the resilience of our brain.is defined as our mind's resistance to injury and impairment.

In this article we will examine the concept of cognitive reserve, particularly in the setting in which it is most commonly used: dementia. We will also describe the factors that influence the presence of enhanced cognitive reserve and memory preservation.

Defining cognitive reserve

The concept of "cognitive reserve" is used to refer to the ability to resist brain deterioration without presenting symptoms. Sometimes, even if there is objective damage to the central nervous system that would justify a diagnosis of dementia, the neuropsychological evaluation does not detect cognitive impairment in the person with impairment.

Once they begin to develop neurodegenerative diseases, people with a high cognitive reserve take longer to show symptoms than those with a lower reserve. These effects have been related to the presence of greater cognitive abilities that make up for the behavioral and neuropsychological deficits characteristic of dementia.

However, in these cases, symptoms usually symptoms appear abruptly, in contrast to the typicalin contrast to the typical progression of this type of disease. This has been associated with the joint failure of the strategies used to cope with impairment; at a certain degree of brain damage the person would be unable to put these compensatory skills into action.

In contrast to the term "brain reserve," which emphasizes the resilience of the nervous system, cognitive reserve refers rather to the optimization of brain resources through various strategies that allow performance to decrease to a lesser extent in the presence of neurological damage. Thus, it is a functional concept, not just a structural one.

Cognitive reserve and dementia

In a 1988 study, Katzman and co-workers found that some people with Alzheimer's disease did not show symptoms of dementia, or they were very mild compared to the neurological damage they had. These people also had a greater number of neurons and their brains weighed more than expected.

The results of this and other studies have been attributed to the existence of cognitive reserve, i.e., a of neurons and synapses prior to the development of the disease.. Cognitive reserve is thought to depend on the degree of physical and mental stimulation of the individual; for example, education and employment reduce the risk of dementia.

Twenty-five percent of older people in whom no cognitive impairment is detected before death meet the diagnostic criteria for Alzheimer's disease (Ince, 2001). Thus, even if someone has a clinical picture of dementia at the neuroanatomical level, if his or her cognitive reserve is high, symptoms may not manifest themselves.

Although cognitive reserve is usually discussed in relation to dementia, it can actually be applied to any alteration of brain functions; for example, increased reserve has been found to prevent cognitive manifestations of head trauma, schizophrenia, bipolar disorder or depression..

Factors that prevent deterioration

There are different types of factors that contribute to the increase of cognitive reserve and therefore help prevent the psychological symptoms of dementia and other disorders that affect the brain.

As we will see, these variables are mainly related to the level of activity and stimulation, both physical and mental..

1. Cognitive stimulation

Several studies have found that continuous cognitive stimulation increases the brain's cognitive reserve. A very important factor in this regard is the level of education, which is associated with greater neuronal connectivity and growth throughout life, but especially at an early age.

On the other hand, professions that are more cognitively stimulating are also very beneficial. These effects have been detected especially in jobs that require a complex use of language, mathematics and mathematics. complex use of language, mathematics and reasoning, and are likely to beand are probably related to less atrophy in the hippocampus, a structure involved in memory.

2. Physical activity

Research on the influence of physical activity on cognitive reserve is less conclusive than that on mental stimulation. It is believed that aerobic exercise may improve cerebral Blood supplyThe neurotransmitter function and the growth of neurons.

3. Leisure and free time

This factor is related to the previous two, as well as to social interaction, which also stimulates brain function. Rodríguez-Álvarez and Sánchez-Rodríguez (2004) state that elderly people who engage in more leisure activities show a 38% reduction in the probability of developing symptoms of dementia..

However, correlational research carries a risk of reversal of causality; thus, it could simply be that people with less cognitive impairment engage in more leisure activities, not that these activities prevent the progression of dementia.

4. Bilingualism

According to research by Bialystok, Craik and Freedman (2007), people who use at least two languages on a very regular basis during their lives take on average 4 years longer than monolinguals to show symptoms of dementia, once the brain begins to deteriorate.

The hypothesis proposed by these authors is that competition between languages favors the development of an attentional control mechanism. development of an attentional control mechanism. This would not only explain the benefits of bilingualism for cognitive reserve, but also the improved cognitive functioning of children and adults who master several languages.

Bibliographical references:

• Bialystok, E., Craik, E. I. & Freedman, M. (2007). Bilingualism as a protection against the onset of symptoms of dementia. Neuropsychologia, 45: 459-464.

• Ince, P. G (2001). Pathological correlates of late-onset dementia in a multicenter community-based population in England and Wales. Lancet, 357: 169-175.

• Katzman, R., Terry, R., DeTeresa, R., Brown, T., Davies, P., Fuld, P., Renbing, X. & Peck, A. (1988). Clinical, pathological, and neurochemical changes in dementia: a subgroup with preserved mental status and numerous neocortical plaques. Annals of Neurology, 23(2): 138–44.

• Rodríguez-Álvarez, M. & Sánchez-Rodríguez, J. L. (2004). Reserva cognitiva y demencia. Anales de psicología, 20: 175-186.

• Stern, Y. (2009). Cognitive Reserve. Neuropsychologia, 47(10): 2015-2028.