Commonly used antidepressant changes the brain’s fat composition

November 10, 2021

Summary: Depression in children and young adults is on the rise. Depression-related suicides are among the leading causes of death among this age group. As a result, doctors are now more likely to prescribe antidepressants in this age group. Prozac (fluoxetine) is among the most used antidepressants in young adults. However, there are worries that it might cause some irreversible changes in the brain. The new study shows that Prozac can alter the fat content of the healthy brain. It remarkably reduces the levels of PUFAs in the brain. PUFAs are essential for the growing nervous system. Though the study is not conclusive, but it shows a need for greater research into the long-term consequences of using these drugs.

Keywords: depression, childhood depression, depression in adolescents, Prozac, fluoxetine, Prozac side effects

Depression and related illnesses are no longer limited to older adults. Studies show that about one-fifth of children and adolescents are at the risk of developing major depression. In fact, suicide is among the leading causes of death among individuals aged 10 to 24 years. Not only that, the prevalence of other conditions like generalized anxiety disorder (GAD), PTSD, and obsessive-compulsive disorders (OCD) are also widely prevalent in this age group1.

Prescribing antidepressants is the primary way of treating major depression, OCD, and other similar mental disorders in young and old. What is alarming is that these mood disorders are on the rise even in very young children. Studies show that there has been a 40% increase in prescriptions of antidepressants in children aged 5-12 years2.

Although these drugs help in severe conditions like major depression, concerns remain about their long-term impact on brain health. Some studies show that in many individuals, these drugs rather increase the risk of suicidal thoughts. These medications might even cause many other unforeseeable effects on the young brain.

Among the most commonly used antidepressants in children and young adults is fluoxetine (Prozac)3.However, this particular drug is also not free from controversy. It might cause some irreversible changes in the brain composition, especially in children and young adults.

Studying the impact of drugs on human brains is complex and often not possible. Thus, researchers at Skoltech University decided to see how the prolonged use of Prozac affects the brain composition of macaque monkeys.

In the study, they found that Prozac causes significant changes in brain composition. It alters the fat metabolism in the brain. It seems to cause changes in gene expression and lipid metabolism.

This finding is relevant, as it is no secret that the human brain is a fatty organ. In fact, 60% of the brain is made up of fat. Lipids are needed in large amounts for maintaining healthy neurons. Lipids are also essential for the formation of myelin sheaths.

Further, it is known that abnormalities in lipid metabolism are linked with a higher risk of Alzheimer’s, depression, schizophrenia, and other brain disorders later in life.

In the study, researchers measured the levels of 300 lipids in the macaque brain. These were macaque given Prozac for a prolonged time. They compared the lipid composition with macaques that were given a placebo4.

The study found that Prozac has a significant effect on PUFAs metabolism. Omega-3 is one of the better-known PUFA that is good for brain health. And it seems that Prozac may reduce its brain levels.

Content of PUFAs is exceptionally high in children or growing brains. Though their level starts falling with age, nonetheless, it is higher in adolescents compared to older adults. Therefore, it only underlines the importance of high PUFAs levels for brain health.

Although, it is not clear from the study what kind of impact these reduced PUFAs levels might have in the long run. Nonetheless, it demonstrated that some harm is possible, and there is a need to understand the phenomenon better when prescribing Prozac to children.

Researchers noticed that there are certain limitations to the study. For example, in macaque monkeys, PUFAs are mainly produced in the body. And they do not have any significant dietary intake of these fatty acids. On the contrary, a human diet rich in fish, seafood, meat, and certain oils, may provide much more PUFAs. It means that such effects may not necessarily occur in humans or might be prevented through PUFAs supplementation.


1. Dwyer JB, Bloch MH. Antidepressants for Pediatric Patients. Curr Psychiatr. 2019;18(9):26-42F.

2. Robinson J. Number of young children prescribed antidepressants has risen by 41% since 2015. The Pharmaceutical Journal. Accessed October 30, 2021.

3. Luo Y, Kataoka Y, Ostinelli EG, Cipriani A, Furukawa TA. National Prescription Patterns of Antidepressants in the Treatment of Adults With Major Depression in the US Between 1996 and 2015: A Population Representative Survey Based Analysis. Frontiers in Psychiatry. 2020;11:35. doi:10.3389/fpsyt.2020.00035

4. Tkachev A, Stekolshchikova E, Bobrovskiy DM, et al. Long-Term Fluoxetine Administration Causes Substantial Lipidome Alteration of the Juvenile Macaque Brain. International Journal of Molecular Sciences. 2021;22(15):8089. doi:10.3390/ijms22158089

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