Race to a Cure Authors
What Happens to Our Brains As We Age?
“Senior moments”. We’ve all heard of these infamous, tiresome qualities associated with becoming older—such as struggling to remember the name of a coworker, politician, or celebrity, only to have it reappear into our mind only a few hours later when we are no longer actively trying to remember. Although we are all prone to certain lapses in memory on occasion, these so-called “senior moments” do tend to increase as we get older. Contrarily, several cognitive abilities do tend to continue to improve with age and there are individuals who seem to be particularly exceptional when it comes to the effects age has on one’s cognitive, physical, and socio-emotional abilities. For example, neuroscientist Lorraine Tyler from the University of Cambridge had discovered that older adults of eighty years of age perform just as well as younger individuals on memory tasks. So, how do our brains change as we age, and what consequences are associated with this?
Unfortunately, from the biological perspective, the ageing process begins extremely early – as early as our twenties! Although we lose neurons (ie. cells in the nervous system, including the brain) very early on in our lives, this is one of the ways in which our cognitive capabilities are refined (ie. through the process of synaptic pruning). According to the American Psychological Association, In this process, the brain removes extra synapses, which allows for the removal of connections the individual no longer needs, strengthening other more important connections. Even where the losses might be detrimental, the human brain is remarkably adept at compensating for these changes. The miniscule but continuous loss of white matter (ie. decrease in the number of myelinated axons) throughout the years causes a general “slowing down” of everyday abilities. This is because these myelinated axons are responsible to act as pathways that carry information around the brain, so their reduction results in the gradual decrease in thinking and processing speed.
Myelinated sheath (Britannica).
However, as we age, the neurons that survive the process of synaptic pruning are those that are more likely to become damaged. The ageing brain typically is characterized by the presence of two crucial devices; the neurofibrillary tangles and the amyloid plaques. The National Institute on Aging states that Neurofibrillary tangles are clumps of a specific protein called “tau”, which build up inside select neurons (ie. particularly those in the hippocampus). Higher numbers of these proteins have been linked to poorer cognitive performance, and extremely high levels are indicative of Alzheimer’s disease. It has generally been believed that these tangles interfere with signalling within the neuron and therefore may increase the risk of cellular death. Amyloid plaques are lumps of beta amyloid protein that build up between the neurons and are also thought to harm synaptic communication. These are also known to be an important marker of Alzheimer’s disease.
Image is courtesy of ResearchGate.
How Do Changes in the Physiology of the Brain Affect Memory and Other Cognitive Functions?
According to the American Psychological Association, research in neuroscience consistently demonstrates that the cognitive functions most likely to be affected by age are:
Overall thinking speed, such as making quick decisions, processing information and mental math
Executive functions, such as planning, thinking ahead, flexibility, and using complex strategies
Memory, such as remembering the names of individuals
A widely accepted view in neuroscience is that ageing causes more specific changes to the brain; some regions of the brain lose efficiency, while others continue to function at their prime. In an article on Ageing and the Brain by R. Peters, we learn more about the science of how some regions lose efficiency.. Notably, the prefrontal cortex and the hippocampus, which is responsible for memory, are particularly susceptible to the effects of age. Moreover, the frontal lobes of the brain, which is responsible for judgement, critical thinking and decision making, tend to have these effects as well, and this is why as individuals become older, they may tend to take less time to stop and think before making decisions and expressing their thoughts. They may also seem more set in their ways or may get caught up in talking about a particular topic and find it difficult to move on to another topic or task. Planning and thinking ahead may also become more difficult.
Two factors of ageing that can be easily overlooked are diminishing eyesight and hearing loss. Both of these critical senses become less efficient as one ages, and this may have serious consequences for one’s safety. In addition, mental processing is far more effortful, which can lead to a sense of being overwhelmed by excessive cognitive load.
Furthermore, decrease in memory abilities is one of the most common effects of ageing on one’s cognitive abilities. An article in Harvard Health Publishing says that generalized changes include having difficulty remembering information that has no specific meaning, such as strings of unrelated words or numbers (this can happen as early as the thirties), words do not come to mind so easily (this can occur as early as middle adulthood but get significantly more noticeable as individuals transition into old age). In this case, the little pieces of information that they feel they must know may seem completely out of reach. Although these feelings are often frustrating, they are incredibly common and the information tends to come back to the mind after some moments, usually when the individual stops consciously trying to remember the information and moves on to another task. Age is especially disruptive to one’s prospective memory, which allows them to remember to do things at a particular point in the future (e.g. going to an appointment, or buying something on a grocery list etc.). This effect can be particularly worrisome, if the task is an important one, such as forgetting to take one’s medication, for example.
However, in contrast to all the cognitive losses mentioned above, vocabulary, knowledge, and wisdom generally continue to grow. In an article on the Upsides of your aging Brain we see that Everyday problem-solving also tends to be unaffected by age and can even continue to improve, except where there is significant pressure of time. There are also some aspects of memory that seem to be completely unaffected by age; in particular, anything that becomes a well-established routine or habit may be generally well-remembered. Lastly, short-term memory tasks, such as temporarily holding a relatively simple piece of information in the mind (e.g. remembering a short phone number or a sequence of words in a list), also seem to be largely unaffected, as long as there are no distractions in one’s process of memorization.
Article Author: Aneri Buch
Article Editors: Edie Whittington, Sherilyn Wen