Finasteride & Neuroactive Steroids: Human Study

Quick Highlights

• This study looked at 12 men with early hair loss who took 1 mg of finasteride daily for 12 months.
• According to this study, several hormones that can affect mood dropped over time during treatment.
• The biggest drops happened in hormones called dihydrotestosterone and allopregnanolone.
• This study suggests that the drop in these hormones might help explain why some people feel sad or anxious while on finasteride.
• The men in this study did not report feeling depressed themselves.

Study Basics

Full study title

"The influence of low dose finasteride, a type II 5α-reductase inhibitor, on circulating neuroactive steroids"

Who was in the study

• 12 men with early hair loss (average age: about 30 years)
• All had hair loss that started before age 30
• They were seeking hair transplant treatment

What they took

• Dose: 1 mg of finasteride by mouth, once a day
• Duration: 12 months

When they checked hormone levels

• Before starting (baseline)
• After 4 months
• After 8 months
• After 12 months

What They Measured

According to this study, the researchers measured 27 different hormones in blood samples taken in the morning. These included:

• Dihydrotestosterone: A hormone made from testosterone
• Testosterone: The main male hormone
• Allopregnanolone: A hormone that can calm the brain
• Pregnenolone: A building block for many other hormones
• Many other related hormones

The study explains that finasteride blocks an enzyme that normally turns testosterone and other hormones into their "5α-reduced" forms. These 5α-reduced forms include some hormones that can affect how the brain feels and works.

How They Measured These Hormones

This study measured hormones in blood, not directly in the brain. Here is how this works and what it can tell us:

Why measure blood?

• These hormones travel through the bloodstream to reach different parts of the body, including the brain.
• Blood samples are safe and easy to collect from people.
• Blood was drawn from a vein in the arm, between 8:00 and 10:00 in the morning.

The method used

• The researchers used a method called GC-MS (gas chromatography-mass spectrometry).
• This is a very precise lab technique that can detect tiny amounts of hormones.
• It works by separating hormones in a sample and then identifying each one by its unique chemical "fingerprint."
• The team added a known reference hormone to each sample to make sure the results were accurate.

What blood levels can tell us about the brain

• Many of these hormones are made in glands (like the adrenal glands) and then travel through the blood.
• Some of these hormones can cross from the blood into the brain, where they affect mood and calmness.
• When blood levels of these hormones drop, less of them may reach the brain.
• Researchers use blood levels as a "window" to estimate what might be happening inside the brain.

Important to know

• Blood levels do not show exactly what is happening inside the brain at any given moment.
• The brain also makes some of these hormones on its own, which blood tests cannot measure directly.
• Still, studies in animals and humans suggest that blood levels often reflect trends in brain levels.
• This is why a drop in blood hormones can hint at possible changes in the brain, but it does not prove them.

Main Results

Hormones that went down

According to this study, several hormones dropped during the 12 months of treatment:

• Dihydrotestosterone: dropped from about 1.93 to 0.70 (a 64% drop)
• Allopregnanolone: dropped from 0.37 to 0.12 (a 68% drop)
• Androsterone: dropped from 1.66 to 0.81 (about 51% drop)
• Epiandrosterone: dropped from 1.37 to 0.57 (about 58% drop)
• Pregnenolone: dropped from 5.46 to 2.14 (about 61% drop)
• Isopregnanolone: dropped from 0.41 to 0.16 (about 61% drop)

All values are in nmol/L (a unit for measuring hormone amounts in blood).

Hormones that stayed about the same

• Testosterone: changed only slightly (from 25.05 to 29.39)
• Estradiol: stayed stable

Hormones that went up slightly

According to this study, some 5β-reduced hormones (a different type) went up a little bit early in treatment but then stabilized.

Changes Over Time

This study reports that the drops happened gradually:

• At 4 months: Dihydrotestosterone had already dropped to about 1.10 (from 1.93)
• At 8 months: It dropped further to about 0.87
• At 12 months: It reached its lowest point at about 0.70

According to the researchers, most of the brain-calming hormones followed a similar pattern: they kept dropping as treatment continued.

Why This Might Matter

According to this study, some of these hormones (like allopregnanolone) work on special receptors in the brain that help with:

• Feeling calm
• Managing anxiety
• Mood balance

The study mentions that other research has linked finasteride to depression in some users. The researchers suggest that the drop in these brain-active hormones might be one reason why some people feel low while taking finasteride.

Important context from the paper

• The men in this specific study did not report feeling depressed
• The paper notes that not everyone who takes finasteride will feel mood changes
• The researchers suggest that people who already tend toward depression might be more affected

What Other Studies Have Shown

The paper mentions several other reports:

• According to one study mentioned, 128 men taking 1 mg of finasteride daily showed higher depression scores after 2 months
• Another report mentioned in the paper found that some men developed moderate to severe depression after 9 to 19 weeks on finasteride, which went away when they stopped taking it
• Animal studies mentioned in the paper showed that blocking the same enzyme that finasteride blocks led to changes in behavior and mood

Study Limits

• Small group: Only 12 men were studied
• No comparison group: There was no group taking a fake pill to compare against
• No mood tests: The researchers did not use questionnaires to measure how the men felt
• Young and healthy: All participants were relatively young men without major health issues

Direct Quotes from the Paper

Here are some exact quotes from the original study:

"5α-Reduced steroids, e.g., 5α-dihydrotestosterone, androsterone, epiandrosterone, 5α-androstane-3α,17β-diol, allopregnanolone, isopregnanolone, and some 5-ene steroids, such as dehydroepiandrosterone and pregnenolone, decreased gradually during treatment."

"Neuroactive 5α-steroids possess anticonvulsant, antidepressant, and anxiolytic effects in addition to altering aspects of sexual- and alcohol-related behavior."

"The decrease of 5α-reduced steroids, especially of allopregnanediol, dihydrotestosterone, and pregnenolone, is probably one of the factors responsible for the increased occurrence of depression in men treated with finasteride, even at low doses."

"Thus, in men with a predisposition for depression, the decrease of antidepressive and antianxiolytic neurosteroids caused by finasteride treatment could be the key which triggers the depressive mood described by other authors."

"Therefore, this medication should be prescribed with caution for patients with high risk of depression."

From other studies mentioned in the paper

On a study of 128 men: "Finasteride treatment in this study increased depression scores significantly, whereas anxiety scores showed a non-significant increase."

— Rahimi-Ardabili et al., as cited in the paper

"Depression, which significantly impairs socio-familial relations, sleep, and eating behavior, and in some cases is associated with marked anxiety, developed after 9–19 weeks of treatment with finasteride and was promptly resolved after suspension of the drug."

— Altomare and Capella, as cited in the paper

"Animal studies suggest that finasteride might alter 5α-reductase activity in some regions of the brain and lead to behavioral and mood changes."

Key Points from This Study

• This study shows that 1 mg of finasteride per day lowered several brain-active hormones over 12 months
• The biggest drops were in dihydrotestosterone and allopregnanolone
• Testosterone levels did not drop much
• According to this study, the researchers suggest that these hormone changes could help explain why some people feel depressed or anxious while taking finasteride
• The paper recommends that doctors be careful when giving finasteride to people who may be prone to depression

Reference

1. Dušková M, Hill M, Stárka L. "The influence of low dose finasteride, a type II 5α-reductase inhibitor, on circulating neuroactive steroids." Hormone Molecular Biology and Clinical Investigation. 2010;1(2):95–102. Institute of Endocrinology, Prague, Czech Republic.