The Connection Between Aging, Cognitive Performance, and Oxidative Stress

Cognitive performance is a critical capability that allows individuals to function accordingly in their everyday lives; it provides humans with the capacity for sustenance and self-preservation and the free will to engage in activities of their choice. However, many researchers have posed a question regarding the sustainability of the human body’s cognitive performance, particularly because cognition may not be an all-enduring ability and is subject to different levels of degradation.

Several studies have proposed this concept, and research shows that several factors could affect a person’s cognitive ability, along with the discovery that multiple types of cognition correlate to specific functionality in the human body.

After several assessments of this proposed thesis, oxidative stress was considered one of the most significant factors correlated to a decrease in cognitive performance. This type of degradation is associated with the inherent decline of the body – aging.

Understanding Aging
As defined by a 2020 study by Kandlur, Satyamoorthy, and Gangadharan, aging is a long process that “involves the systemic loss of functioning.” Considering the inevitability of this phase in the human life cycle, many industry stakeholders are interested in understanding the various mechanisms behind aging and how they can be slowed or even prevented.

Aging is one of the most notable factors associated with a neurodegenerative decline, including the development of conditions such as Alzheimer’s and Parkinson’s disease. Experts believe this is due to the changes brought about by aging, such as an increase in amyloid plaques, accumulation of alpha-synuclein in the brain, loss of brain volume, misfiring neurons, and neurofibrillary tangles.

Many theories have been proposed to explain the connection between aging and the loss of cognitive performance. Still, one proposition that holds the most promise is the theory that the overproduction of free radicals within an aging body results in the accumulation of damage and the degradation of critical neurological pathways.

Cognitive Aging

Cognitive aging is a state wherein individuals gradually lose their cognitive function due to an assumed deterioration in the structures of the nervous system – resulting in an evident decrease in cognition and functionality, i.e., poor memory, difficulties in activities requiring spatial awareness, impaired speech, and loss of attention.

The process and symptoms of cognitive aging are not the same in every individual, as several factors can either slow down or hasten brain aging. For instance, genetic factors are crucial in determining the resilience of an individual’s cellular composition – allowing for resistance against accumulative damage and preventing any evident signs of decline far longer than in other individuals who may be more susceptible to these changes.

Defining Oxidative Stress

Oxidative stress is observed when there is an accumulation of damage within the body – particularly in the brain – due to an increased number of free radicals or reactive oxygen species (ROS) present.

Reactive oxygen species are typically addressed by the presence of antioxidants within the body, i.e., glutathione. Glutathione is a significant antioxidant in the body’s tissues which helps remove generated reactive oxygen species, such as peroxides, aldehydes, and other toxic chemicals that might enter the human body.

Oxidative Stress as a Driver for Decreased Cognitive Performance

2018 study by Hajjar et al. conducted a longitudinal examination of middle-aged patients (mean age of 49) to determine whether glutathione levels within the body correlate with a decrease in cognitive functionality.

Upon analyzing the data, it became evident that there was a direct correlation between the decreasing levels of glutathione in the body as the patient ages and the functionality of the brain’s cognitive domain. In addition, the amount of oxidized glutathione (those reacted with the free radicals present in the body) had an inverse relationship with the memory scores of the patients.

From these results, it is evident that although there could be several other components associated with aging and the loss of cognitive function, there seems to be an overwhelming dominance of reactive oxygen species within the body as humans age – resulting in a decreased level of antioxidants that could prevent degradation.

The findings that age-related oxidative stress contributes to declines in cognitive function and performance pose many questions for researchers investigating this relationship; how can this be prevented? How can individual susceptibility to oxidative stress be determined? And finally, which clinical interventions can be used today to mitigate the effects of oxidative stress tomorrow?