Loss of memory with age is a widespread concern

any older adults have concluded that the only age change really worth caring about is that which slowly robs them of their ability to think.  Generally, muscle weakness, loss of balance and even loss of independence are often rated as less important than the loss of mental capacity that is defined as dementia.  It is important to know that dementia is not a normal age change but rather a neurodegenerative disease that at present has no cure or well defined cause.  Since aging is the main risk factor for disease and since the environment contributes significantly to the rate of aging , not intervening with known strategies will negatively impact memory as well as overall brain function.  Therefore, for longevity building, it becomes especially critical to know the latest and best information that will help preserve brain function.  This blog reviews the science on this topic and relates proven interventions. 

Numerous tests track aging of the brain

Thinking is complicated and so there exist many tests that measure each unique aspect of mental function.  For example, there are tests to measure verbal memory, visual memory, associative memory, source memory, perspective memory, processing speed, spatial navigation, and the most complex, executive function.  Interestingly and importantly, results of many studies that assessed these various brain functions over extended periods of time (more than 30 years in some studies) showed that some components of brain function have the potential to decline while others are quite stable throughout the lifespan.  Thus brain aging appears to be “selective”.   It then becomes important in longevity building to optimize those activities which have a tendency to deteriorate.

Brain functions that remain constant with age

Mental functions that do not change with age include semantic memory, most aspects of language, autobiographical memory, emotional processing, and automatic memory processes. Specifically, semantic memory is the memory of facts and knowledge learned over the lifespan.  This remains stable with age although the speed with which this knowledge is retrieved may be slowed.  Language refers to things such as use of appropriate grammar rules and pronunciation.  These are not forgotten and also remain constant.  Autobiographical memory is an individual’s personal history and it, too, is unwavering with time.  Emotional processing refers to typical emotional responses to problems or difficult situations.  Emotional processing takes many forms e.g. abrupt, calm, thoughtful, anxious etc.  Individual emotional processing modes do  not change with age and for the most part, one’s emotional processing at 90 years will mirror that at 30 years.  Finally, automatic memory processes remain stable over time.  Automatic memory relates to things done with minimal mental input or done by rote or constant repetition e.g. driving a car, riding a bike, making coffee, playing tennis.  They are activities that have become so routine that they seem to be accomplished without thinking.  Instability or loss of automatic memory processes usually signals the presence of neurodegenerative disease.

Brain functions that decline with age; longevity building with proven interventions

Mental functions that weaken with age include a) a slowing of information processing speed, b) a decline in executive function, and c) a decrease in specific memory functions that include encoding and retrieval processes, associative, source finding and prospective retention.  This breaks down into the following: information processing speed refers to the quickness at which one can process and respond to information.  This decrement is highly significant since it is a major reason for accidents, mistakes and even falls.  This means that the mental response to novel situations is slowed and depending on the situation, may result in an unfavorable outcome.  Fortunately, processing speed can be improved with practice (see below).  Executive function encompasses various memory skills and abilities to use information to solve daily problems.  Thus, the age-associated decrease in executive function will impinge on important activities such as shopping, banking/finances, house management, medication oversight and meal preparation.  The decline in specific aspects of memory are not as serious as the reduction of information processing speed and executive function but are frequent complaints of the older adult such as not remembering who told me that or where the information came from (source finding memory) or not remembering the reason for doing something, for example, opening the refrigerator door (encoding and retrieval memory) or working on a project and forgetting about a future task such as to turn the oven on at specific time (prospective retention memory).  Whereas these cognitive activities tend to deteriorate with age, proven interventions of intense learning experiences can significantly reduce their loss.

Longevity building – proven interventions to slow brain aging through brain remodeling

Results of numerous animal studies and now many studies in humans using sophisticated imaging techniques such as an MRI and other scans show that brain aging can be minimized and cognitive function of the older adult can be maximized by

a) a program of aerobic exercise (Insight 4)

b) continued engagement in serious mental stimulation

c) mastery of new skills

d) making sure vision and hearing is the best possible. 

These lifestyle choices improve/maintain the connections between brain cells (neurons) and assure their survival.  The effect on the brain is referred to as brain remodeling or positive neuroplasticity. Thus these specific interventions physically alter or remodel the brain in a favorable way.

1) Longevity building with aerobic exercise

Aerobic exercise yields many benefits.  With regard to cognitive function, aerobic exercise improves blood flow to and throughout the brain, promotes formation of new blood vessels, and  improves brain metabolism, thereby reducing accumulations of neurotoxins, substances that harm or kill nerve cells.  Recently, results of animal studies, now supported by data obtained in man not only in young but also older individuals, show increased formation of nerve cells as well as more nerve connections in specific brain regions (brain remodeling).  This supports earlier studies that show a correlation with fitness and cognitive function such that the higher the fitness level, the better the score on various cognitive tests (mentioned above) and the better the brain activity as recorded by a functional MRI scan (a scan that can localize which part of the brain is doing the thinking).

2) Longevity building with participation in intellectually complex work

There is considerable debate as to whether retirement harms brain function.  Initial findings reported a significant decline in brain activity following retirement.  This implied that loss of work-related brain stimulation was a major factor in brain aging and that the continuation of intellectually complex work after retirement served to prevent this loss.  Continuation with complex intellectual activities remains important but current data point to a high degree of variability regarding brain stability after retirement.  The best studies indicate that decline in brain function is evident following retirement but the onset and rate of this decline is highly variable and depends on many factors, for example, complexity of job, health at retirement, satisfaction with the job, educational level.  What is not disputed is that:  part time work post retirement preserves cognition for a significant period of time, hence continuation of complex intellectual activities remains of importance.  Additionally, several small clinical studies show that engagement in solving of complex abstract problems reduces brain aging.

3) Longevity building with learning a new skill

Skill training is specific training for a specific task.  It includes, for example, learning a new language, learning to play a musical instrument, learning computer skills, learning to crochet, and learning to ski.   Learning a new skill, although relatively easy for an adolescent and young adult,  has generally been considered more challenging for the older adult.  However, skill learning prevents decline in brain function.  This is confirmed by studies using brain scans that show positive brain remodeling in the older adult equal to that of the young adult.  Furthermore, it is now known  that for a) skill mastery and b) long term retention, the older adult benefits from training sessions that are seriously challenging and complicated.  This approach favors the best outcome for the older adult. 

Two important clinical trials (ACTIVE, IMPACT) evaluated the effect of proprietary computer programs to improve memory, reasoning and processing speed with specific practice exercises over a 10 week period.  Both studies yielded positive results such that practice test scores in memory, reasoning and processing speed increased with these programs.   The extent to which these improvements are maintained over time has not been studied as yet but would be important to know.

4)  Longevity building with sensory enhancement

There are a number of age changes that diminish the sight and hearing of the older adult.  In the absence of disease these age changes are correctable but unfortunately, they are frequently ignored.  As a result, eye sight and hearing are compromised.  The denial of hearing loss is especially common.  What is not appreciated is that failure to correct these sensory deficiencies is a big factor promoting cognitive decline.  This is because  these deficits reduce the quality of information that is received.  Referred to as “noisy processing” the brain receives inaccurate or fuzzy information which does nothing to promote learning and intellectual stimulation.  Over the long term, little knowledge is gained, and little thinking is done, with the outcome of accelerating brain aging.  Corrective lenses and hearing aids will add measurably to optimizing brain function.

5)  Adequate sleep

Adequate sleep is an important factor in preserving cognition.  This will be the topic of my next blog which points out the relation between adequate sleep and the newly discovered filtration system in the brain that removes neurotoxins.  This is a potential link between sleep, cognitive decline and neurodegenerative diseases.