Midlife Factors that Affect Quality of Life in Old Age

abstracts &commentary

Sources: Reed DM, et al. Predictors of healthy aging in men with high life expectancies. Am J Public Health 1998;88: 1463-1468; Swan GE, et al. Association of midlife blood pressure to late-life cognitive decline and brain morphology. Neurology 1998;51:986-993.

Healthy aging, defined as surviving to late life free of major life-threatening illnesses and maintaining the ability to function physically and mentally, has become a medical issue of critical importance as the size of the population 65 years of age and older increases. Chronic disease and disability in the elderly have led to unprecedented increases in the cost of medical care. The result is an important need to identify modifiable risk factors for disease and to use this information as the basis for systematic interventions designed to enhance the health of the elderly.

Reed and associates sought to identify risk factors that predict staying healthy in old age. They studied men of Japanese ancestry living in Hawaii, a group with one of the highest life expectancies in the world, at more than 79 years. More than 8000 men were followed for 28 years with repeat examinations and surveillance for deaths and incident clinical illness. Of 6505 healthy men at baseline, 39% died prior to the final examination. Among the 3263 survivors, 41% remained free of major illness, 40% remained free of both physical and cognitive impairment, and 19% were free of both illness and impairment.

The most consistent predictors of healthy aging were: low blood pressure, low serum glucose, not smoking cigarettes, and not being obese. High forced expiratory volume and low alcohol intake were strong predictors of survival, but were not independently related to the other outcomes of freedom from clinical illness and impairment. Physical activity measurements were not associated with any of the outcomes. (See Table.) Reed et al concluded that much of the illness and disability in the elderly is related to risk factors present at midlife.

    Table
    Predictors of Healthy Aging
    Biologic Measures
    Survival
    Function
    High blood pressure
    -
    -
    High serum glucose
    -
    -
    Obesity
    -
    -
    Grip strength
    0
    +
    Lung function
    +
    0
    Health Habits    
    Cigarette use
    -
    -
    Physical activity
    0
    0
    Alcohol use
    -

    - = Indirect association
    + = Statistically significant direct association
    0 = No significant association
    ________________________________________

The study of Swan and associates supports the thesis that midlife risk factors affect old-age health. Swan et al investigated the association between midlife systolic blood pressure (SBP) and late-life cognitive decline and brain morphology. The present study included 392 surviving members of an earlier study in whom SBP had been measured in 1970, 1980, and 1985. They underwent an additional examination, including SBP measurement, neurobehavioral testing, and brain MRI obtained between 1995 and 1997. Subjects with high midlife SBP experienced a greater decline in cognitive performance and had more white matter hyperintensities (WMHI) in late life than did those with low midlife SBP. Decreased brain parenchyma and increased WMHI were associated with a late-life decline in neurobehavioral function that was independent of age, education, and baseline levels of cognition. Therefore, Swan et al concluded that midlife SBP is a significant predictor of both brain atrophy and a decline in cognitive function in late life.

Commentary

In the elderly, beyond biological aging, most physical disability and need for long-term medical care results from clinical illnesses such as heart disease, stroke, diabetes, arthritis, blindness and hip fracture. Both the studies abstracted above indicate that much of the underlying disease pathology in the elderly begins in young or middle adult life. Reed et al’s study indicates that low levels of known risk factors such as hypertension, diabetes, smoking, and obesity, as well as an absence of chronic diseases consistently predict healthy aging. Swan et al provide supporting evidence of the negative effect of hypertension on brain structure, midlife SHP leading to decreased brain volume, increased WMHI, and cognitive decline.

These two studies reflect a growing recognition of the importance of disease prevention. Poor health late in life is not inevitable and modifiable risk factors make a greater contribution than was previously thought. It is never too late to institute blood pressure reduction and stop smoking in the elderly: the earlier the therapeutic intervention, the greater the dividends later in life.