Middle-aged and older men aren’t the only ones experiencing erectile dysfunction. But experts say the number of younger men who have the ailment is likely not as high as recent reports have suggested.

A recent survey in the United Kingdom concluded that about half of men in their 30s struggled to get or maintain an erection. More than a third of men under 30 reported they were affected by erectile dysfunction (ED). Slightly more than 40 percent of men in their 40s and 50s were affected.

But those numbers go against what other studies have found — and the confusion may be over how erectile dysfunction is defined, U.S. sexual health experts told Healthline.

“It’s contrary to many other studies,” said Dr. Irwin Goldstein, director of sexual medicine at Alvarado Hospital in San Diego.

The main causes of ED have to do with cardiovascular issues, he said, which can affect blood flow to the penis and are more likely to happen in middle age and older.

Depends on the definition

Respondents in the survey, conducted by the British chain Coop Pharmacy, cited stress, anxiety, fatigue, and excessive drinking as the most likely reasons for their condition.

Goldstein said that suggests the men were thinking of an occasional problem in bed, rather than ED.

Goldstein said ED is “the persistent and consistent inability to maintain an erection through satisfactory intercourse.”

“If you say someone anytime in their life had a difficult time getting an erection, that wouldn’t be the classic definition,” he said.

Dr. Daniel Shoskes, a Cleveland Clinic urologist, had a similar opinion of the survey.

“Properly conducted studies have shown much lower numbers at those ages, although not zero,” he told Healthline.

Shoskes added that it’s possible the respondents were reporting any sexual dysfunction, possibly even including premature ejaculation.

“Psychological or stress-related episodes of ED are very common and probably have happened to every adult male,” Shoskes added.

Methodological differences between studies on the prevalence of ED have been a problem for a while.

A 2002 review that attempted to give a complete picture of the problem across the general population was “hampered by major methodological differences between studies, particularly in the use of various questionnaires and different definitions of ED.”

It found prevalence ranged from as low as 2 percent in men under 40 to as high as 86 percent in 80-year-olds. But it called for more studies to establish the “true” prevalence.

Younger men and ED

That doesn’t mean young males can’t have ED or that many don’t.

Goldstein said that it’s just that ED is “pretty rare” until around age 50. That’s when prevalence hits about 52 percent — a higher percentage than the U.K. survey found.

Among men under 40, prevalence of moderate to severe ED is 2–26 percent, according to Dr. Amin Herati, director of men’s health at Johns Hopkins University School of Medicine in Maryland.

But, he did say younger men with ED is a population that’s “overlooked.”

Psychological factors can affect younger patients’ ability to get and maintain erections, for instance, particularly through the use of certain drugs such as selective serotonin reuptake inhibitors (SSRIs) used to treat depression.

Young men can also increase their risk of ED through activities such as bike riding, which can damage the arteries that carry blood to the penis.

Herati also cited as factors: alcohol use and overuse of pornography, which other experts have said has contributed to a decrease in the frequency of sex among millennials.