As we already know, an optimal state of physical and mental health acts as a preventive factor against the cognitive deterioration experienced with age. When we refer to the type of factors that prevent deterioration, we often refer to a concept called “reserves”.But… what do we know about the cognitive reserve and the brain reserve ? what is their influence on impairment?

In the following article we will discuss the reserve types available to our brain and explain their contribution as a preventive factor against deterioration .

Brain reserve and cognitive reserve

The reserve capacity is that which enables the brain to cope with changes due to normal ageing or neuropathological processes by delaying the appearance of clinical symptoms.

According to Arenaza-Urquijo and Bartrés-Faz (2013) there are two interrelated theoretical models for the study of the reserve :

1. Brain reserve model

This type of reserve corresponds to the passive model , which refers to the anatomical potential of the brain : brain size, number of neurons, synaptic density, etc. This type of reserve poses a static and invariable model, since it emphasizes genetic and anatomical factors.

2. Cognitive reserve model

It corresponds to the active or functional model, referring to the individual ability to use pre-existing or alternative (compensatory) cognitive processes or neural networks to optimally perform a task. Since this reserve can be increased due to the influence of various environmental factors to which we are exposed throughout our lives (they will be explained later), it could be said that this model, unlike the previous one, responds to a dynamic character.

What is the influence of the reserve on aging?

Now that we know both types of reserve, v we want to explain their contribution to the ageing process or to the normal or pathological ageing process.

Brain reserve

Brains that have a high degree of this reserve have a greater base substrate , which will allow them greater resistance to brain damage in the face of pathological phenomena or during aging, thus favoring a prolongation of the preclinical state in the processes of pre-dementia and dementia (Arenaza-Urquijo and Bartrés-Faz, 2013).

As for regulatory ageing, higher reserve estimates will correspond to more structurally preserved brains.

Through neuroimaging techniques such as anatomical magnetic resonance, we can detect brain changes in people with high cognitive reserve that can serve as indicators of a pathological disorder in old age before it has manifested itself clinically, such as in Alzheimer’s disease.

Cognitive reserve

The cognitive reserve refers to cognitive processing capacity . Such reserve allows the use of neuronal networks in an effective way trying to diminish the impact of the changes associated to aging and neuropathological processes (Arenaza-Urquijo y Bartrés-Faz, 2013). It could be said that the cognitive reserve enhances plasticity and interneuronal connectivity.

Several studies have shown that a high cognitive reserve acts as a preventive factor against deterioration and, in the case of dementias, will generally delay the appearance of symptoms and, consequently, the diagnosis. However, the underlying pathological progress will be the same regardless of its cognitive reserve, therefore, the symptoms will be presented when the pathological process is more advanced and, consequently, the progression of the disease will be more rapid once the threshold of clinical and cerebral involvement has been exceeded .

This is because a brain with high cognitive reserve will present more facility for the use of alternative neural networks when the normally used networks are damaged, however, this compensation will end when the neurodegenerative disease becomes more severe (Pousada and De la Fuente, 2006).

In terms of normative ageing, cognitive reserve means better performance , a more functionally efficient brain, which is why it is important to maintain activities that stimulate our cognitive functions throughout life. In several studies (Arenaza-Urquijo and Bartrés-Faz, 2013), high levels of mental activity have been associated with up to 50% less risk of developing dementia .

Therefore it is essential to take into account cognitive training as an intervention to minimize the risk of cognitive impairment associated with age and/or dementia. Likewise, it has been shown that there are also other types of environmental factors that contribute as a protective factor against cognitive decline, such as: the state of physical and mental health, occupation, sleeping hours, diet, leisure activities and the maintenance of social relationships.

This type of reserve can be analysed by means of a functional magnetic resonance imaging (fMRI) or by means of positron emission tomography (PET).

Some conclusions

In conclusion, it has been shown that the reserve capacity acts as a protective factor against the manifestation of the brain changes underlying the aging process or the disease by tolerating further damage to their brains and minimizing, in turn, the impact of the disease on its clinical manifestations.

This fact is of great importance since, although the underlying process is the same, the patient will maintain a quality of life longer. The reserve, therefore, turns out to be one of the many factors that demonstrate why there is interindividual variability in terms of the symptomatic manifestation of the same brain disorder.

It is therefore interesting to stress the need to carry out future research focused on the exhaustive study of specific activities that contribute to increasing the cognitive reserve and to analyse their consequent interaction with biological factors.

Bibliographic references:

  • Arenaza-Urquijo, E.M., and Bartrés-Faz, D. (2013). Cognitive reserve. In Redolar-Ripoll, D. (Ed.), Neurociencia cognitiva (1st ed., pp. 185-200). Madrid: Editorial Médica Panamericana.
  • Pousada, M., and De la Fuente, J. (2006). Memory and attention. In Villar, F., and Triadó, C., Psicologia de la vejez (1ªed., pp. 114-140). Madrid: Alianza Editorial, S.A.