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Developmental Psychology


At the turn of the last century, only half of all adults in the United States lived to be older than 65 years of age. Today, at the turn of the new century, the majority of U.S. citizens can expect to live well into their seventies, and perhaps beyond. In fact, it is estimated that by the year 2030, there will be more Americans over age 65 than in any other age group (Kail & Cavanaugh, 2000). Advances in nutrition, health care, and technology may allow us to postpone or even eliminate some of the symptoms of physical decline associated with aging.

Although the average human lifetime has increased significantly in the past century, the maximum life span has changed little, peaking at slightly over 100 years. The oldest person on record was Jeanne Calment of Arles, France, who was 121 when she died in 1996. (Calment is quoted as saying that she remembered seeing Vincent Van Gogh when he bought art supplies in her father's store.)

The Aging Brain

Over the years, many of us will lose some brain cells through these natural causes. By late adulthood, losses due to attrition could amount to as much as 5 to 10% of our total brain mass (Coleman & Flood, 1986; Hayflick, 1996). Although this sounds like a significant amount, normal neuron losses rarely result in serious mental impairment. This is partly the result of the extraordinarily large number of neurons with which we started life, and partly due to redundancies (backup systems) present in the brain.

Researchers have observed that the production of neurotransmitters such as acetylcholine, norepinephrine, serotonin, and dopamine often decreases with age (Whitbourne, 1999). Diminished levels of these substances may be partly responsible for changes in memory, mood, motor abilities, and sleep patterns in the elderly.


Dementia is a type of cognitive impairment characterized by memory losses, confusion, and disorientation. It is more prevalent in older adults, occurring in approximately 15% of individuals over age 65 (Elias, Elias, & Elias, 1990). Although people have sometimes mistakenly assumed that with increasing age comes an inexorable mental decline or "senility," the symptoms of dementia are usually the result of brain damage or disease, and are not a natural or direct consequence of aging itself. The concept of inevitable senility in late adulthood now appears to be a myth. There are many possible reasons for the increased risk of dementia in late adulthood, including:

  • Alzheimer's Disease. One of the most devastating afflictions of the aging brain is a condition first described by the German neurologist Alois Alzheimer in 1907. Alzheimer investigated the case of a 51-year-old woman, Auguste D., who suffered from severe dementia. After her death, an autopsy revealed an unusual number of plaques and tangles among the neurons in her brain, with the loss of a significant amount of brain tissue in the cerebral hemispheres. This condition, now known as Alzheimer's Disease, is responsible for more than 60% of all cases of dementia.

    Alzheimer's Disease is a degenerative disorder of the central nervous system that causes severe mental and physical impairment and is eventually fatal; it is the fourth leading cause of death in the United States. Although it is not exclusively a disease of the elderly, the risk of developing Alzheimer's Disease increases dramatically over time, doubling every five years after the age of 60. The chance of being diagnosed with Alzheimer's Disease approaches 50% by age 85.

  • Strokes. Interruptions of the blood supply to the brain are more likely as we age. A cerebral vascular accident (CVA) occurs when there is a blockage or hemorrhage of a cerebral artery supplying the brain with oxygen. We often refer to these catastrophic incidents as strokes. Symptoms of a CVA can range from death to severe loss of functioning (e.g., paralysis or aphasia). Approximately 20% of all cases of dementia in the elderly are caused by some type of vascular problem, usually associated with the complications of strokes, high blood pressure, heart disease, or constriction of the blood vessels that supply blood to the brain.

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