30 SCIENTIFIC AMERICAN A P R I L 2 0 0 1

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The six leading killers of Americans—coro-nary heart disease, stroke, lung cancer,colon cancer, diabetes and chronic ob-

structive pulmonary disease—were responsi-ble for 43 percent of all deaths in 1998. Thesesix are also the major “lifestyle” diseases—

that is, diseases that trace mainly to impru-dent living, such as poor diet, obesity, lack ofexercise, and cigarette smoking. Indeed, shiftsin lifestyle account for much of the change inmortality rates over recent decades. Coro-nary heart disease (CHD), stroke and coloncancer rates declined among both sexes.Rates of lung cancer and chronic obstructivepulmonary disease (COPD), both of whichresult overwhelmingly from cigarette smok-ing, declined among men but have been ris-ing among women, a pattern that reflects thelater adoption and subsequent abandonmentof cigarettes by women as compared to use

by men in the years after World War II. Lungcancer and COPD rates among women, how-ever, are expected to turn down eventuallybecause of women’s declining use of ciga-rettes since the 1970s. Diabetes registered abig increase in mortality rates, apparently re-sulting from the growing trend to obesity.

The prospect for future declines in theleading chronic diseases depends in part ontrends in risk factors. Prevalence of cigarettesmoking, which sends more than 400,000Americans a year to a premature death, ap-pears to be stabilizing at about 25 percent ofthe population. More disappointing is the risein obesity. The substantial declines in preva-lence of high serum cholesterol and highblood pressure of recent decades may be dif-ficult to maintain, as those most concernedabout their health have already mended theirdestructive ways, whereas those practicing aless prudent lifestyle will be less inclined tochange. That suggests that mortality rates ofthe major chronic diseases will not decline asfast in the coming years as in the past, but itis likely that the number of deaths fromlifestyle diseases will climb dramatically after2010, when the baby boomers enter old age.

With few exceptions, such as the discov-ery of insulin, “magic bullets” have played aminor role in the prevention, cure and pallia-tion of lifestyle diseases. This could change be-cause of new work now under way, includinggenetic research and promising cancer treat-ments. Such research, if successful, will prob-ably have its greatest impact beginning in thenext decade.

Lifestyle BluesWHEN IT COMES TO COMBATING HEALTH PROBLEMS BROUGHT ON BY HIGH LIVING, THE RECENT IMPROVEMENTS MAY BE OVER BY RODGER DOYLE

BY

THE

NU

MB

ERS

50

40

30

20

10

CIGARETTESMOKING

HYPERTENSION

HIGH SERUMCHOLESTEROL

OBESITY

1960 1970 1980YEAR

PERC

ENT

1990 2000

SOURCE: Centers for Disease Control and Prevention

THE SIX LEADING LIFESTYLE DISEASESDEATHS IN 1998 PERCENT CHANGE IN LEADING RISK FACTORS

(THOUSANDS) MORTALITY RATE , 1980 –1998

CORONARY HEART DISEASE 460 –47 C,H,S,O,PSTROKE 158 –38 C,H,S,OLUNG CANCER 155 +6 SCHRONIC OBSTRUCTIVE PULMONARY DISEASE 113 +34 SDIABETES 65 +35 OCOLON CANCER 57 –24 D,PALL CAUSES 2,337 –19

Risk-factor abbreviations: C = high serum cholesterol; H = hypertension; S = smoking cigarettes; O = obesity; P = physically inactive; D = diet inadequate (for example, insufficient fruits or vegetables)

SOURCE: American Public Health Association. Changes in mortality rates are based on age-adjusted data.

RISK-FACTOR PREVALENCE IN U.S.

High cholesterol is defined asamounts greater than 240

milligrams per deciliter of blood.Hypertension is defined as

having a medically untreated systolic blood pressure (the first

number in a reading) of at least 140 millimeters of mercury or

a diastolic pressure (the secondnumber) of at least 90. Obesity

is defined as a body mass index of30 or greater (calculated by

dividing the weight in kilograms by the square of the height

in meters). Pulmonary diseasemortality includes deaths from

emphysema, chronic bronchitis,asthma and other obstructive

diseases of the lungs.

NEED TO KNOW:BODILY HARM

Copyright 2001 Scientific American, Inc.