The Aging Brain & Designs for Strong Minds™
By the age of 75, the average adult has half the brain cells in the occipital cortex (visual area) of the average 20-year-old. This massive loss may be due in part to the effect aging has on our eyes. With time, the cornea (the transparent fluid-filled bag in front of the lens) changes in molecular structure. As a result, light rays are bent and scattered more haphazardly which we experience as blurred vision. The shape of the cornea also changes. It flattens so that, by age 60, many of us require the help of eyeglasses or magnifying lens for close, detailed work.
The iris (which controls the size of the pupil) is also altered by aging. Its fibers may atrophy so that the size of the pupil is reduced. This means fewer photons can enter our eyes, requiring more light for close activities such as reading. The atrophy also reduces flexibility so our eyes cannot adjust as quickly to sudden change in light intensity. In other words, we become less sensitive to gradual contrasts in light or shadow.
As we age, our eyes grow more and more lens tissues. Because previous tissues are not removed, the new layers compress the older ones to the center, thus increasing the lens' diameter. Between 20 and 70 years of age, the average lens triples in mass. This is another cause of farsightedness. Moreover, the lens takes on a yellowish hue. It becomes increasingly difficult to distinguish greens, blues, and violets. And yellow itself becomes less "bright." Our color perception is altered.
Of course, these changes don't happen overnight. The changes are so gradual that many times we're more apt to blame something in the environment ("They don't make lights as strong as they used to") or lose interest in activities we once enjoyed than to recognize that our perceptual ability has altered.
Contrast the devastation of the occipital cortex with the vitality of the prefrontal cortex (associated with memory). In most people, the prefrontal lobe shows virtually no loss of brain cells with age. Some studies suggest that memory impairment in the aged is not so much loss of specific facts as it is a reduced ability to readily retrieve what is known. This may be due to a reduction or disconnection of neural pathways.
This raises an interesting possibility regarding the preservation of mental facilities as we age. It is known that an active social life greatly contributes to the maintenance of a healthy brain. Perhaps part of the reason is that interaction with other people provides increased sensory stimulation that keeps brain cells alive and active. It is not the stimuli itself that matters, but the way the stimuli is processed through intentional interaction. In other words, when we relate to other people, we have to engage our frontal lobes (the judgmental and decision making part of the brain) to organize the sensory stimuli we're receiving and to act upon it.
With this possibility in mind, Designs for Strong Minds™ (DSM) programs can provide systematic, progressive training of the visual systems through intentional behavior. DSM does this with graphic puzzles organized to challenge and enhance cognitive and relational thinking skills such as comparative and sequential thinking, part-whole relationships and categorization. In effect, the puzzles encourage participants to exercise the muscles that are most likely to atrophy with age—the ones that enable us to note and observe fine details that enrich our lives. Consequently, DSM helps make people aware of what they have gradually been missing.
© Copyright 2004 Donalee Markus, Ph.D. & Associates