What changes occur to the brain as people age?

Picasso, Georgia O’Keefe and Grandma Moses, artists. Louise Nevelson, sculptor. Albert Einstein, physicist. Giuseppe Verdi, musician. Robert Frost, poet. Each of these great minds worked differently, but they all shared an outstanding trait: they were creative and productive in old age. They defied the popular notion that aging always leads to a pronounced decline and loss of cognitive ability.

Neuroscientists now believe that the brain can remain relatively healthy and fully functioning as it ages, and that diseases are the causes of the most severe decline in memory, intelligence, verbal fluency and other tasks. Researchers are investigating the normal changes that occur over time and the effect that these changes have on reasoning and other intellectual activities.

It appears that the effects of age on brain function vary widely. The vast majority of people get only a bit forgetful in old age, particularly in forming memories of recent events. For example, once you reach your 70s, you may start to forget names or phone numbers, or respond more slowly to conflicting information. This is not disease. However, other individuals develop senile dementia, the progressive and severe impairment in mental function that interferes with daily living. The senile dementias include Alzheimer’s and cerebrovascular diseases and affect about one percent of people younger than age 65, with the incidence increasing to nearly 50 percent in those older than 85. In a small, third group, that includes the Picassos, Einsteins and others, mental functioning seems unaffected by age. The oldest human, Jeanne Calment, was considered to have all her wits during her 122-year lifespan. The wisdom and experience of older people often make up for deficits in performance.

The belief that pronounced and progressive mental decline is inevitable was and still is popular for several reasons. For one, until the 20th century, few people lived to healthy old ages. In 1900, when life expectancy was about 47 years, three million people, or four percent of the population, were older than age 65, and typically they were ill. In 1990, when life expectancy was more than 75 years, 30 million people, or 12 percent of the population, were older than age 65. A generation ago, frailty was seen among people in their 60s; today it is more typical among those in their 80s. Moreover, few people challenged the notion that aging meant inevitable brain decline because scientists knew little about the brain or the aging process.

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