Impotence: more than a middle-age metaphor.

More men than previously though experience some degree of impotence, report researchers analyzing data from what they describe as the largest sex survey of the general population in 40 years.

In fact, slightly more than half of the 40-to 70-year-old men questioned had trouble getting or keeping an erection at least once in the six months preceding the interview, say John B. McKinlay of the New England Research Institute in Watertown, Mass., and his team.

To conduct the survey -- part of the 1987 to 1989 Massachusetts Male Aging Study -- trained interviewers went to the men's homes in the Boston area and had them fill out a questionnaire about their sexual activities. They also asked the men about their physical and mental health and drew samples of blood. Almost 1,300 men participated, 95 percent of them white, the researchers report in the January JOURNAL OF UROLOGY.

Earlier studies of the prevalence of impotence were smaller, aimed primarily at men with medical problems, and found lower rates of impotence than this study, says McKinlay. The Boston study did not look at the biological mechanisms responsible for impotence, as some other studies have done (SN: 7/4/92, p.10).

The researchers ranked the men as completely, moderately, or minimally impotent, based on their answers to nine questions about the frequency of their erections and sexual activities and their satisfaction with their sex lives.

The biggest factor correlated with impotence was age, even when considered apart from illness, they report. Only 5 percent of 40-year-olds reported suffering from complete impotence, but 15 percent of 70-year-olds did. While about two-thirds of the 40-year-olds reported no problems with potency, only one-third of the 70-year-olds made that claim.

As other studies have found, heart disease, diabetes, and hypertension increase a man's chances of experiencing impotence. In fact, 39 percent of heart disease patients and 15 percent of hypertension patients in the Boston study were completely impotent, compared to 9.6 percent of the entire group of volunteers. This disease-related impotence may stem from medications -- but only in part, the researchers report.

The combination of heart disease and smoking cigarettes amounts almost to a prescription for impotence, they discovered. Heart patients who smoked were almost three times as likely to suffer total impotence as those who didn't smoke. Hypertensives who didn't smoke proved no more likely to experience complete impotence than others in the study.

Folklore to the contrary, testosterone concentrations failed to correlate with impotence, they report. Yet the study provides another reason for men to improve the concentrations of high-density lipoproteins (HDL) in their blood. Men with high HDLs were less likely to report impotence than other men in the study.

Futhermore, the researchers found, the higher a man's concentration of the pituitary hormone metabolite dehydroepiandrosterone (DHEAS), the lower his risk of impotence. Other research suggests that men with high DHEAS may have a lower incidence of heart disease.

Mental well-being and personality clearly affect potency, the team says. Among men ranking high for suppressing anger -- as measured by such things as fuming -- or expressing anger, about 35 percent had moderate impotence and almost 20 percent experienced complete impotence. Nearly 90 percent of the men who ranked highest on the measurement of depression reported moderate or complete impotence. Men with very dominant personalities -- who, for example, attempt to control others -- reported fewer potency problems than the rest of the group, the researchers report.

The prevalence of impotence makes it "a major health concern," McKinlay concludes. Impotence accounted for some 400,000 outpatient visits and 30,000 hospital visits in 1985 in the United States, they add.