Baldness drug finasteride 'cuts men's drinking'

“Anti-baldness drug can cause men to lose interest in alcohol,” reports the Mail Online.

This report is based on a small survey of young men who had been taking the drug, finasteride, for hair loss. Impotence and decreased libido are recognised side effects of this anti-male-hormone drug, and all 83 men in this study had experienced sexual side effects that lasted at least three months after they stopped taking it.

The survey found that the men reported drinking less at the time of the survey than before they started taking the drug. However, this was on average five years earlier, so it is not clear how well these men could remember what they drank so far in the past.

Also, as the study had no control group who didn’t take the drug, it’s not possible to say that these changes wouldn’t have happened naturally over time as the men aged. The results may also not be representative of what might be seen in older men, men taking the drug for its other use (enlarged prostate), or men who do not experience the sexual side effects of the drug.

Overall, these findings are inconclusive. Larger studies, ideally with a control group, are needed to assess the effects of the drug on alcohol consumption.

Where did the story come from?

The study was carried out by a single researcher from The George Washington University in the US. No sources of funding were reported. It was published in the peer-reviewed journal Alcoholism: Clinical and Experimental Research.

The Mail Online reports the results of the study, but not any of its fairly extensive limitations.

What kind of research was this?

This was a cross-sectional study reporting on the alcohol consumption among men taking the drug finasteride. This anti-male-hormone drug is licensed to treat benign (non-cancerous) enlargement of the prostate and male pattern hair loss.

The recognised side effects of the drug include sexual problems such as decreased libido, impotence and erectile dysfunction. It may also have effects on the nervous system. The researchers reported that finasteride has been shown to reduce alcohol intake in male mice, but no studies have assessed this in humans.

This study relied on men reporting their own alcohol consumption before and after taking the drug in a single survey. This is likely to be less reliable as men may not accurately remember their consumption in the past. Asking the men to keep an alcohol diary before and after they started taking the drug would be a more reliable approach.

The study also didn’t include a comparison group not taking the drug. Therefore, the result cannot conclusively show that the drug itself is definitely causing a change in alcohol consumption.

What did the research involve?

The researchers surveyed the alcohol consumption habits in 83 men aged under 40, who had been taking finasteride to treat or prevent male pattern hair loss. These men had experienced persistent sexual side effects but were otherwise healthy.

The men were reported to be recruited from the author’s previous studies on persistent sexual side-effects of finasteride. These men had side-effects for at least three months despite stopping finasteride. Men who had sexual dysfunction before taking finasteride, had chronic medical conditions, current or past psychiatric conditions, or had taken psychiatric medication were excluded.

The survey asked about their average weekly alcohol consumption before they started taking finasteride, and at the time of the interview. A glass of wine, can of beer, or shot of hard liquor was considered a standard drink.

What were the basic results?

Sixty-three of the men reported drinking at least one alcoholic drink per week before starting finasteride. Among these men, at the time of the survey:

• 65% reported reduced alcohol consumption 
• 32% reported no change in their alcohol consumption
• 3% reported an increase in their alcohol consumption

On average, of the men who reported drinking alcohol, the average number of drinks per week reduced significantly – from 5.2 before finasteride to 2.0 after finasteride. As the men had stopped taking finasteride, they were not taking the drug at the time of assessment.

The authors reported that although they were not asked about this specifically, some men volunteered the information that they could not tolerate alcohol as well after starting to take finasteride. Eighteen men reported giving up alcohol entirely.

How did the researchers interpret the results?

The researchers concluded that among men who developed persistent sexual side effects from finasteride and stopped taking the drug, almost two-thirds reported reduced alcohol consumption.

Conclusion

This relatively small study in a very select group of men provides only limited evidence of the effects of finasteride on alcohol consumption in men. Its limitations include:

• The study didn’t include a comparison group not taking the drug. Therefore, the result cannot conclusively show that the drug itself is definitely causing a change in alcohol consumption, rather than the men just having changing alcohol tolerance as they got older.
• The study asked men to remember what their alcohol consumption was before taking the drug – on average about five years previously. This is likely to be less reliable as men may not accurately remember their consumption in the past. Asking the men to keep an alcohol diary before and after they started taking the drug would be a more reliable approach.
• The study only used a crude assessment of the number of drinks consumed, the size and alcohol content of these drinks may vary and this could affect comparison of before and after findings.
• The study did not say exactly how men were selected to take part, or whether they knew the purpose of the study. The men’s responses may have altered if they knew that finasteride may have an effect on alcohol consumption.
• The men all had persistent sexual dysfunction following taking finasteride for male pattern hair loss. The results may not apply to other men taking the drug, for example those without these side effects, or those taking it for an enlarged prostate.
• The author reported that many of the men in the study experienced depressive symptoms, and this may have affected their alcohol consumption.

As the author acknowledges, more research would be needed to determine the effects of finasteride on the nervous system and alcohol consumption.