Hi @Triptoqueen
This is a common misunderstanding and in general placebo effects are often misunderstood.
When we say ADs are 15% better than placebo what we mean is that in randomized clinical trials where people were randomly assigned to take either a sugar-pill without any active ingredient (placebo) or the tested pill (ADs in this case) on average 60 out of 100 people given dummy pills got better and 75 out of people on the AD got better. So 15 more people out of 100 got better because of the AD. The number needed to treat (NNT) which means how many people need to take these drugs in order for one person to benefit for ADs is 7. For insulin it's 1. Note that ALL these trials are conducted on people who are moderately or severely depressed, not just mild cases of depression or anxiety. Most of these studies are done for 6 weeks.
What is more interesting is that in most of these trials there is what we call a run-in phase where ALL people in both arms of the clinical trial i.e. those that were assigned to take the placebo and those that were assigned to take the drug are initially given only sugar pills for the first two weeks and those who improve during those two weeks are then taken out of the trial, so placebo responders are weeded out first. Which means that placebo responses are even higher than documented in the trial.
So the conclusion then is that of the 75 people who got better on ADs, 60 would have gotten better with only sugar pills. Why do they get better with just sugar pills? We don't exactly know. It is possible that depression by itself resolves without pills in most people if given enough time. Or it may be the pills give people hope that the depression is curable that makes the body mobilize itself. It may be the attention that people get from the doctor. We simply don't know. But placebo effects exist.
People suspected that a placebo effect existed for a long time but its power was clearly demonstrated when a doctor gave women with morning sickness ipecac a substance whose effect is to induce vomiting. He told the women that this was a drug that actually cured morning sickness. And sure enough for a substantial percentage of the women their morning sickness went away DESPITE being given a substance that should have made it worse BECAUSE the women were told that it would.
Placebo effects are prominent in trials of pain, anxiety, Parkinson's disease but also in cancer and diabetes - virtually every area of medicine. That is why we test drugs against placebo before approval - to be sure that the effect we observe is due to the drug and not just to our belief in it. Because drugs have serious side effects, we want to know that the benefits justify the costs. Placebo effects exist in surgery as well. Some sham surgeries provide as much improvement as the real surgery. Given that a surgery is very 'costly' and 'risky' we need to know that it has an impact. However, not all surgeries are tested against placebo the way drugs are.
To approve/license a drug the FDA requires that it is better than placebo in 2 trials ONLY. The company can run 15 trials of which 13 show that the drug is not better than placebo or that it is worse than placebo but as long as the company can show that the drug is better than placebo in 2 trials the drug gets approved. If you look at the totality of the trials submitted to the FDA the majority of the AD trials are negative - i.e. they do not show that the drug is better than the placebo and in some cases they show that the drug is worse than the placebo - i.e. more people in the placebo arm of the trial get better than people in the AD arm. Note that companies have to disclose all trials that they have run to the FDA but they don't have to disclose all these negative trials to doctors or patients. These statistics are obtained by a Freedom of Information act from the FDA and listed in the paper below:
Now the fact that a when we say that a drug is not better than placebo does NOT mean that it has no effect on the body. Take as an example a chemotherapy drug that is being tested on breast cancer and fails against placebo. The trial shows that the drug is not better than a sugar pill IN TREATING CANCER - 20% of people on the sugar pill get better and 18% of the people on the tested drug get better. BUT it also doesn't mean that the drug did not have an effect on the body. Chemotherapy drugs are often toxic and this drug may have damaged someone's heart or kidneys or killed them. What we mean when we say it is no better than placebo is that it was not better for the effect that we tested - could be depression or anxiety or OCD. In our case if a drug is no better than placebo then that means it did not improve depression symptoms better than the placebo. It doesn't mean that a drug that is no better than placebo in treating depression can't cause dependence. Lots of ADHD or cancer drugs are no better at treating depression than sugar pills but they do have an effect on the heart and do cause physical dependence the way that ADs cause physical dependence.
Antidepressants do have effects on the body. In fact they can have routinely have severe start-up effects - they often increase anxiety and worsen symptoms such as sleep in the first few weeks. That is why when people say that they immediately made them feel better, I would suspect that it is more likely to be a placebo effect than a true physiological response. But for any individual it is impossible to say whether the effect was a placebo effect or a genuine physiological effect.
ADs also numb people's feelings which is probably what many people find helpful. But they don't numb just anxiety and depression, they also numb sexual feelings, they numb joy, they numb anger, they numb love for spouses and children (things people are not very willing to admit), they numb ambition and motivation. Helen Fisher has videos and a book about their effect on romantic relationships.
As many people have said this is an effect that works for them, especially those who find themselves in situations that are not fixable or easily fixable - bad marriages without financial independence and with care responsibilities were one example given - life can be cruel to many of us. They can be a band-aid that helps people function. But the vast majority of the people prescribed these medicines are not in these situations - they can change their circumstances - quit a bad job, get a divorce, create more social connection, exercise, see a therapist, treat an underlying disease etc. Different things work for different people. A lot of women who are prescribed these medicines have vitamin deficiencies, thyroid issues, are going through menopause. These drugs are too costly in terms of side effects and physical dependence to justify the risk of prescription for hot flashes (there are also better treatments). Yet 30% of women who go to their GP with menopause symptoms are offered these drugs. [Guardian article, can look up] They end up being a good way to shut women up at the doctor's office and when they get angry about the injustices of the world such as what is demanded of them. 75% of ADs are prescribed to women.
SSRIs and even more likely SNRIs can also create feelings of euphoria, recklessness and general activation in people taking them. That is why your chance of being diagnosed with bipolar disorder increases if you are already on SSRIs. This doesn't mean that they 'unmasked' a latent bipolar disorder, it means that they caused activation and mania that was then misdiagnosed as bipolar disorder. The incidence of bipolar disorder in the general population has risen with the incidence of SSRI/SNRI prescriptions. [Check Out the book Anatomy of an Epidemic by Robert Whitaker, an award winning journalist for the Boston Globe). And it is not because people did not go to be diagnosed with bipolar because of stigma before - bipolar is so debilitating that it is unlikely that so many people were underdiagnosed before the advent of ADs (similar to schizophrenia).