Have we been treating depression the wrong way for decades? | CBC News

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This is an excerpt from Second Opinion, a weekly analysis of health and medical science news. If you haven’t subscribed yet, you can do so by clicking here.


A new analysis of the cause of depression has apparently changed what we know about this common condition and has called the use of antidepressants into question. But it can also leave patients with more questions than answers as the science evolves.

A systematic overview of 17 studies published in molecular psychology on July 20 analyzed the decades-old theory that depression is caused by low levels of serotonin and found that there was “no consistent evidence” of “an association between serotonin and depression.”

The theory that depression is caused by a chemical imbalance in the brain has been around since the 1960s. But for years, many experts have doubted this, feeling it oversimplified a complex condition.

“The serotonin theory is very old and has been very popular since the 1990s when the pharmaceutical industry started promoting it,” said Dr. Joanna Moncrieff, a professor of psychiatry at University College London and lead author of the study.

“But since around 2005, probably a little bit before that, there’s been kind of a buzz that actually the evidence isn’t very strong or it’s inconsistent. Some studies are positive, some studies are negative, but no one really has that evidence.” nowhere”. .”

Moncrieff and his team set out to challenge the serotonin theory in a systematic review of the available research. They also went a step further in their conclusion by suggesting that antidepressants are not effective in treating depression and have worked largely like a placebo.

“Evidence from placebo-controlled trials shows that antidepressants are a little better than a sugar tablet,” he said. “And if that little difference doesn’t have to do with rectifying a chemical imbalance, improving low serotonin levels, what does it have to do with it?”

The research paints a compelling picture that depression is not caused solely by low serotonin levels. Many experts say this is now widely accepted, and it’s also true that antidepressants can be extremely beneficial for some patients, even if we don’t know exactly why.

So where does this leave patients and doctors, and could the analysis affect how we treat depression in the future?

Are antidepressants effective against depression?

Antidepressants are widely believed to affect the behavior of neurotransmitters, chemical messengers in the brain such as serotonin and dopamine, in a way that can alter emotions and mood to help improve symptoms of depression in some patients.

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People with depression can face a wide range of symptoms, including persistent feelings of sadness and hopelessness, changes in appetite, lack of sleep, fatigue, irritability, and loss of interest in hobbies and social connections that can affect daily life.

While it’s not clear exactly how antidepressants work biologically to alleviate these symptoms, it’s clear that they can still be of great help to some patients.

“It’s a typical discovery in medicine: you find a drug that works, but you’re not quite sure why,” said Dr. Phil Cowen, a professor of psychopharmacology at the University of Oxford.

“[The review] it’s a debunking exercise, and in a way they’re criticizing earlier studies that were difficult to do,” he said. “These [older] The studies were clearly very roundabout and messy, and I don’t think anyone thought they were that good.”

Moncrieff’s team found that some depressed patients actually had higher levels of serotonin in certain areas of the brain, and in some cases, long-term use of antidepressants may actually lower the amount of serotonin, although the findings were “inconsistent.” “.

“I think it makes a big difference, because how [antidepressants] the work actually influences whether they work,” he said. “It influences how useful we think they are.”

The findings have caused quite a stir in the media and scientific community, with hundreds of media outlets covering the study, quickly placing it in the top five percent of all research rated by Altmetrica company that analyzes where published research is shared.

Findings of this perceived magnitude may have a seismic impact on how we understand and treat a pervasive condition like depression, which affects an estimated one in eight Canadians at some point in their lives.

While the research questions the very nature of what we know about depression, many doctors are hesitant to change the way we treat it.

Antidepressants can be a “lifesaver” for some

Dr. David Juurlink, director of clinical pharmacology at the Sunnybrook Health Sciences Center in Toronto, said he’s not surprised by the findings, because the chemical imbalance theory for depression is now seen as an “obvious oversimplification” of a condition complex.

“While I think doctors are prescribing serotonin-enhancing antidepressants far too often, in part because of this oversimplification, it’s important to recognize that they do improve well-being in some patients,” he said in an email.

“How exactly they do it is not as clear as we have been led to believe.”

A bottle of antidepressants is displayed in Miami, Florida. A new analysis suggests that depression is not caused by low serotonin levels and that antidepressants are not effective in treating it. (Joe Raedle/Getty Images)

Dr. David Gratzer, a psychiatrist and attending physician at the Center for Addiction and Mental Health (CAMH) in Toronto, said he wasn’t surprised by the findings, just that they received as much attention as they did.

“This suggestion that depression has to do with serotonin all the time hasn’t been accepted by psychiatrists for many years, probably many decades,” he said, adding that researchers are “terribly biased” in their evaluation of antidepressants. .

“Their article shows that things are much more complicated than serotonin, no wonder, and then they turn around and say, ‘See, that’s another example of the fact that antidepressants don’t really work.’ One does not necessarily give rise to the other.

Gratzer said he still regularly prescribes antidepressants as a treatment option for depression, and has no plans to stop based on research.

“That’s not going to change. These drugs work,” he said.

“An antidepressant is not necessarily [recommended] in all people who have depression; In fact, some people may do better with talk therapy, but it’s definitely a tool in our toolkit and, to be frank, it’s a lifesaver for some of our patients.”

Research casts doubt on antidepressants

Moncrieff said the research found that another way antidepressants may work is by desensitizing the brain to the negative emotions associated with depression. In theory, that could also affect other feelings.

He said that one of the effects that previous studies have reported in patients is “emotional numbing,” in which they not only don’t have unwanted emotions like depression and anxiety, but positive emotions like joy and happiness.

“There might be some people who feel like that’s the effect they want. But I think in general people aren’t going to want to be emotionally numb, not for long periods anyway, so I think it totally changes the type of decisions … people might think about antidepressants,” Moncrieff said.

Chris Davey, head of the psychiatry department at the University of Melbourne, said in an email that undermining the trust that people with depression have in their treatment can be “very damaging.”

“People stop taking their medications suddenly, without supervision,” he said, “which can cause a dramatic deterioration in their mental health.”

Davey said he’s concerned that the document downplays a treatment option that can be incredibly beneficial for some patients, especially when alternatives aren’t always available for those at risk of major depression.

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“East [research] it should not make any difference in the treatment of depression. I hope it makes people realize that depression is a very complex condition with no simple explanation,” Davey said.

“Everyone should know that improving their diet, getting more exercise and paying attention to their sleep can help. Everyone should have access to psychotherapy. And for those people who don’t find those things helpful, that’s when we think of medication.” .

Gratzer said there are many new areas of research on treatment options for depression that may be beneficial, including novel ways of delivering psychotherapy, emerging medications, and discoveries such as the use of ketamine.

Ketamine is a general anesthetic first approved in Canada in the 1960s for medical or veterinary surgery, as well as a psychedelic party drug sold on the illicit market. It is also increasingly used as an effective, fast-acting treatment for depression at low doses, by working to restore synapses in the brain that are destroyed by stress.

There is “an understanding that certain life experiences might be more connected, so research is very active. Maybe at the end of the day, we understand that depression is not a disease,” Gratzer said.

“As is often the case with mental health care, these are early days.”

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