Almost half of American women and a third of men experience sexual problems, according to the first major study of American sexual dysfunction in 50 years.

The study of more than 3,000 men and women found that 43% of women and 31% of men experienced sexual difficulties, ranging from impotence to lack of desire and pain during intercourse.

Despite the fact that new impotence cures are mostly targeted at men, it is younger women who are most likely to experience sexual problems. They along with older men experience the greatest difficulties.

The University of Chicago report, published in the Journal of the American Medical Association, analysed information from the National Health and Social Life Survey.

The researchers say older men have problems with impotence and lack of desire, while young women are more likely to have a higher turnover of sexual partners as well as spells of sexual inactivity.

This instability, as well as sexual inexperience or traumatic sexual experiences in the past, contribute to sexual dysfunction, says the report.

Sexual pleasure

Women were more likely to complain of lack of interest in sex, with some 22% reporting low sex drive.

For men, premature ejaculation was a major problem, with 21% complaining of this, compared to 14% who said they lacked interest in sex. Five per cent said they were impotent.

The report also found that:

• Poverty and few educational qualifications were major factors in sexual dysfunction. Women without a high school diploma were twice as likely to have a low sex drive, suffer painful intercourse and have problems achieving orgasm;
• Married people are less likely to have sexual problems;
• Stress influences sexual performance and enjoyment;
• White women tend to suffer pain more than black women, but are less likely to experience low desire, while Hispanic women suffer consistently fewer sexual problems than all other women. Differences between men were less clear-cut, but were similar to women.

The researchers say their results are significant given increased interest in sexual dysfunction due to the growing number of new treatments coming onto the market - such as the impotence drug Viagra.

They call for more recognition of the problem.

"This report provides the first population-based assessment of sexual dysfunction in the half-century since the Kinsey report.

"With the strong association between sexual dysfunction and impaired quality of life, this problem warrants recognition as a significant health concern."