Critical Psychiatry Textbook, Chapter 2: Are Psychiatric Disorders Mainly Genetic or Environmental? (Part Two)


Editor’s Note: Over the next several months, Mad in America is publishing a serialized version of Peter Gøtzsche’s book, Critical Psychiatry Textbook. In this blog, he discusses the problems with observational studies and other flaws in ADHD research. Each Monday, a new section of the book is published, and all chapters are archived here.

Affective disorders

For affective disorders, some authors expressed less certainty than for schizophrenia. In one textbook, the authors claimed that the risk of affective disorder is increased 3-4 times if a parent is depressed,19:210 and the risk of bipolar is increased 4-6 times if a first-degree relative is bipolar,19:216 but they also admitted that it is very difficult to separate inheritance and environment and to investigate if the changes are a cause or consequence of the depressive condition.19:210

A major risk factor for becoming depressed has nothing to do with biological psychiatry but is simply living a depressing life you feel you cannot escape from. There was very little information in the textbooks about this. One book said that stress, living conditions, and trauma can play a role for affective disorders but not how much, in contrast to its claims about the role of genes, which was 50%.17:353 Another textbook mentioned trauma, especially in relation to the first manic episode,18:113 and a third emotional abuse, neglect, and physical abuse with odds ratios as high as 9 to 12.16:263 It also noted that steroids, birth control pills, and oestrogen-blocking drugs increase the risk of depression but there was no mention that psychiatric drugs, e.g. benzodiazepines, depression pills, and ADHD drugs, can also cause depression,7,8,11,34,44,45 even though this is highly relevant, given their widespread use.

This was a general problem with the textbooks. I gave another example just above of the psychiatrists protecting their guild interests by not mentioning that the drugs they use can cause the very disorders they try to treat. This is dishonest and unhelpful.

Illustration depicts a giant glowing brain with tiny people standing all around it

ADHD and the fallibility of observational studies

For the ADHD diagnosis, risk factors included the mother’s prenatal intake of tobacco, alcohol, or cocaine; decreased intrauterine growth; foetal exposure to insecticides, lead, or mercury; pre-eclampsia; premature birth; complicated births with hypoxia; low birth weight; postnatal infections; exposure to heavy metals; and possibly neuroinfections.17:612,18:229

It was claimed that even though environmental factors may contribute, they play a minor role.18:229

It should always be remembered that such claims about causality come from observational studies. They might therefore not be correct, but I did not notice any reservations in the text-books.

In contrast, top researchers in epidemiology have strong reservations about what their colleagues publish. Observational studies are fraught with difficulties, which is easy to realise if we look at nutritional research.46 People who eat little fruit and vegetables, or drink more than others, cannot be compared to vegetarians and teetotalers. They differ from them in all sorts of ways that could influence their longevity. Therefore, if nutritional advice is to be believed, it must come from carefully conducted randomised trials.

If we are to rely on observational evidence, high quality research is required, and the signal must be substantial because there is so much bias in these studies. Top epidemiologists have stated that, because it is so easy to be fooled, any less than stunning results are almost impossible to believe.47 Some said that even a threefold risk increase is not persuasive, and that they can only be persuaded if the lower limit of the 95% confidence interval falls above a threefold increased risk.

When I examine claims made by psychiatrists by looking up the sources, I almost always find that the claims cannot be substantiated. To show you how this works, I examined one of the claimed risk factors for ADHD, low birth weight. I found a relevant article immediately by googling low birth weight ADHD, which mentioned that “Several studies have reported that children with a low or extremely low birth weight are as much as 3.8 times more likely to meet diagnostic criteria for ADHD.”48 This is bad science. If we describe several studies, we should not cherry-pick the one with the most extreme result but should say what they show on average, or what the median result was.

The authors quoted four studies, and I looked up the first one. It included 137 very low birth weight (VLBW) children that were compared at 12 years with a sample of matched peers for several psychiatric symptoms.49 The main risk was ADHD, which was diagnosed in 31/136 (23%) of the VLBW children, compared to 9/148 (6%) of peers.

The risk ratio was 3.75, but I calculated that the 95% confidence interval went from 1.85 to 7.58. This means that the true risk of getting an ADHD diagnosis is likely to be between 2 and 8 times higher for VLBW children than for normal children.

Assuming the result is correct, which we cannot know, as positive results get published more often than negative ones (and I happened to select the most positive one), we may calculate how big the study should have been if the lower limit of the confidence interval should exceed 3. The lower limit becomes 3, if I multiply all numbers by 10. Thus, the study should have been 10 times bigger to arouse any interest among top epidemiologists.

This is a general problem with observational studies. They are usually far too small, and considering their inherent biases, with the additional risk of selective publication of results that happened to be positive by chance, this means that most results from observational studies are misleading. Even if the studies are very large, they are often misleading, as we cannot eliminate the biases, no matter how we try to adjust for them statistically.

The VLBW study was biased. A table showed that parents of VLBW children were socioeconomically disadvantaged compared to the control group. Furthermore, the authors noted that parents with psychiatric disturbances were more likely to have children who were also vulnerable to psychological problems; that mothers of VLBW children were more depressed than mothers of other infants; and that most VLBW children had limited access to their mothers during the first six months of life. The authors found this of particular interest. So do I, as this could be the explanation for their findings rather than low birth weight.

It is not possible to adjust reliably for such differences with statistical methods. An ingenious study, in which a statistician used raw data from two randomised multicentre trials as the basis for observational studies that could have been carried out, showed that the more variables that are included in a logistic regression, the further we are likely to get from the truth.50 The statistician also found that comparisons may sometimes be more biased when the groups appear comparable than when they do not; that adjustment methods rarely adjust adequately for difference in case-mix; and that all adjustment methods can on occasion increase systematic bias. He warned that no empirical studies have ever shown that adjustment, on average, reduces bias.

His study may be the most important one I have come across in my whole career. But I have not met a single researcher who did not know him personally, that was aware of his highly important results.

This is not to say that observational studies cannot be useful. Many things cannot be studied in randomised trials and we therefore have no other option than to do observational research. But it is unacceptable that the textbooks almost always described the results of such studies as if they represented the truth, with no caveats.

Other flaws in the ADHD research

One textbook provided the sobering information that ADHD is defined arbitrarily as one end of a normal distribution curve, and that brain development is delayed but not qualitatively different from that in healthy children.18:229

If this is correct, we would expect more of those children born in December to have an ADHD diagnosis and be in drug treatment than those born in January in the same class, as they have had 11 fewer months to develop their brains. This is exactly the case. A Canadian study of one million school children showed that the prevalence of children in drug treatment increased pretty much linearly over the months from January to December,51 and 50% more of those born in December were in treatment.

There are other studies that show the same. This means that if we approach the children with a little patience that allows them to grow up and mature, far fewer would get an ADHD diagnosis.

The diagnosis arises primarily from teacher complaints and parents are often told that their kid cannot come back to school unless he or she is on an ADHD drug. A general practitioner told me that a schoolmistress had sent most of her pupils for examination on suspicion of ADHD.7:138 It was clearly she who was the problem, not the kids, but as soon as the kids are branded with ADHD, it relieves everyone of any responsibility or incentive to redress the mess they have created, either at school or at home.

We have decided as a society that it is too laborious or expensive to modify the kids’ environment, so we modify the kids’ brain instead. This is cruel, as I shall explain in Chapter 9. The United States spends over 20 billion dollars a year drugging children for ADHD, which is enough to pay the mid-career salaries of an extra 365,000 teachers.52 And this goes up and up. The number of children with an ADHD diagnosis increased by 41% in just 8 years, from 2003 to 2011.53

Only one of the textbooks mentioned any of the important studies of the prevalence of the ADHD diagnosis in school classes according to age.17:51 The belief in the false story about ADHD being a brain disease is so strong that it is close to impossible to correct the harmful narrative.

The indoctrination is very effective. In 2022, one of my colleagues gave a lecture in critical thinking for psychiatry residents. He asked them to review three studies.

One study showed that 16% of those with an ADHD diagnosis had genetic abnormalities (copy number variants), compared with 7% in the controls.54 The researchers concluded that ADHD was a genetic disease. The residents were asked if this small difference was significant and could be applied to ADHD as a diagnostic category.

The second study looked for a genetic abnormality in neuropsychiatric disorders and is often cited for providing evidence of it.55 The researchers reported that there was a common genetic component involved in the pathogenesis of five neuropsychiatric disorders. One of the disorders was ADHD. They found that those with ADHD were three times more likely to have this abnormality. But if you combine the data from two tables, you will find that only 0.3% had the genetic abnormality, so 99.7% didn’t have it. But because only 0.1% of controls had it, the odds ratio was three.

The third study found that children with an ADHD diagnosis have smaller brains than other kids.56 The effect size was 0.1, which means that patients with the diagnosis have a 47% chance of having a brain bigger than normal.57 The effect size is also called the standardised effect size. It is the effect divided by the standard deviation of the measurements. This allows comparisons of measurements on different but similar scales. If, for example a scale has a 10-fold greater range than another scale, the standard deviation will also be 10-fold bigger, and the effect sizes can therefore be combined in meta-analyses.

The residents emphasised that genetic differences were highly significant and said that the brain volume study suggested that ADHD was a neurodevelopmental disease.

My colleague was flabbergasted. He told the residents that the data showed that nearly all the kids diagnosed with ADHD didn’t have a genetic abnormality; that the odds ratio for the five-disorder study was meaningless; and that the brain volume study showed that there was a 96% overlap between kids with the diagnosis and kids without.57

The residents then got hostile. Didn’t the lecturer understand that ADHD and the other dis-orders were biological disorders; that they were illnesses like diabetes or cancer?

My colleague had seen much insanity in psychiatry, but he told me that this was the most hopeless thing he had ever experienced. It is frightening that such people are supposed to take care of psychiatric patients in an evidence-based fashion. They are clearly not able to do this, as it requires that you have a minimum understanding of science.

The study that claimed that children with an ADHD diagnosis have small brains has been widely condemned. Lancet Psychiatry devoted an entire issue to criticisms of the study. Allen Frances, chair of the DSM-IV task force (DSM is the Diagnostic and Statistical Manual of Mental Disorders, issued by the American Psychiatric Association), and Keith Conners, one of the first and most famous researchers on ADHD, re-analysed the data and found no brain differences.58

The original researchers wrote in the discussion that “our results coming from highly powered analysis, confirm that ADHD patients truly have altered brains, i.e. that ADHD is a disorder of the brain. This is a clear message for clinicians to convey to parents and patients, which can help to reduce the stigma that ADHD is just a label for difficult kids and caused by incompetent parenting.”56

The stupidity in this message is heart-breaking. One of the critics wrote in Lancet Psychiatry that “there is no point in conveying that a child with ADHD has a brain disorder.”59 Of course not. It is not true, and it does not reduce stigma to tell such nonsense to clinicians, parents and children; it increases stigma.

The American Academy of Child and Adolescent Psychiatry writes on its homepage:60 “ADHD is a brain disorder. Scientists have shown that there are differences in the brains of children with ADHD … some structures in the brain in children with ADHD can be smaller than those areas of the brain in children without ADHD.”

In September 2021, The World Federation of ADHD International Consensus Statement was published.61 It presented what the authors called “208 evidence-based conclusions about the disorder,” but several of these were incorrect, e.g. “When made by a licensed clinician, the diagnosis of ADHD is well-defined and valid” and that treatment with ADHD medications reduces substance abuse, educational underachievement, and criminal activity (see Chapter 9).

There were 80 authors, so most of them cannot have contributed much to the paper. They did not specify which contributions they made but many of them had numerous conflicts of interest in relation to the drug industry. The paper asserted that there is a “polygenic cause for most cases of ADHD, meaning that many genetic variants, each having a very small effect, combine to increase risk for the disorder. The polygenic risk for ADHD is associated with general psychopathology … and several psychiatric disorders.”

The great deception of doctors and the public occurs, among other reasons, because very small group differences compared to controls are represented as abnormalities found in individuals diagnosed with ADHD, even though the study data, when properly parsed, show that not to be true.57 Once the data are reviewed, it becomes clear that decades of research into possible abnormalities in genes, brain volume, and brain chemicals all turned up negative.


To see the list of all references cited, click here.


Mad in America hosts blogs by a diverse group of writers. These posts are designed to serve as a public forum for a discussion—broadly speaking—of psychiatry and its treatments. The opinions expressed are the writers’ own.


Mad in America has made some changes to the commenting process. You no longer need to login or create an account on our site to comment. The only information needed is your name, email and comment text. Comments made with an account prior to this change will remain visible on the site.


  1. The early experiences of a pre-term low birth weight infant will be at constantly being stuck with needles, not being held/cuddled, being alone in an incubator.
    So this is the ultimate childhood trauma and a rather good proof for an environmental factor.
    Additionally many have neurodevelopmental delays for medical reasons, hypoxia, intracerebral bleeds etc.
    Therefore is a low birth weight not a great example that ADHD is genetic.

    Report comment

  2. I keep thinking a lot about the structure of our society and its influence on science. From childhood to old age we are under control of the state and those getting salaries from controlling us are connected to the state directly or indirectly. Children are forced to learn and adults are forced to work.

    That creates a big group of people that suffer from that and cannot therefore follow those orders. A diagnosis means that you are labeled as “not to be forced as much as others to educate and to work” or “not to be forced at all to educate and to work” or “medicated to let others work and study”.

    There is always a political pressure to get as many people as one can get into the employed workforce. So the main use of the diagnosis system for “neurological disorders” and “mental illnesses” is to divide people in groups that are controlled and handled differently.

    Those with diagnosis defend it passionately, because they know they cannot perform as well as others and will suffer if they are handled under the same rules. Group controlling some other group will defend diagnoses passionately, because medicines give them a tool to make their work easier. For both groups, diagnosis takes the blame away from them. You are not a bad student. You just have a genetic problem. You are not a bad teacher. Those under your care just have sick and disordered people among them.

    So there is a big market for those stories of illnesses and disorders and strong motivations to defend them that matter a lot more than being reasonable. Those people defending something untrue may seem just uneducated fools, but for them their wellbeing is connected to that story. Because medical science has already answered that need, that means those groups with wellbeing connected to some narrative have multiplied with professionals offering services to the original groups.

    Changing the narrative to something that is more truthful means hurting hundreds of millions of people so as a group there is a strong pressure to defend something untrue and to prefer bad research over the quality one.

    Controlling people with medications instead of changing the environment and taking care of individual needs is always easier in a society that creates a pyramid-like hierarchy where smaller groups control bigger groups. Because for each group with similar status their wellbeing is mostly dependent only on those above them and following their decisions, the pressure to change the environment that would come from lower levels of hierarchy is non-existent compared to pressure from higher levels.

    If this abstraction of that phenomenon is correct then the way to change it would be simple – when changing motivations among hierarchy the narrative would change and there would be no more as strong pressure for an invalid stories. That would require some way for the needs of those under a rule to bubble all the way up in hierarchy. The most obvious method is giving those under a rule like students a way to decide some part of a daily salary of those above them in hierarchy.

    In a wider picture that would mean that all structures of power should go in both directions. Those directly ruling some group should also be ruled by those they are ruling. Then that ruling group would again push that motivation of the bigger group under their care to the smaller group that has authority over them. That would repeat all the way up to the upper levels of the pyramid.

    If invalid psychiatric narratives are mainly used as a controlling and self-defense methods instead of changing the environment, this should remove the majority of necessity for them. When the necessity to defend invalid results is lesser and there would be no big market for false information, bad science should start disappearing.

    Report comment

  3. Happiness does not mean that your brain is healthy. It’s metaphore. False empiricism is based on this secret fallacy that there’s something wrong with the brain as if brain and biology were property of monism and consequently of Marxism. Psychosis is not brain illness, depression is not brain illness just because monism wants spiritualism and convenience in life. Do not simplify psyche for the needs of pragmatism. Psyche’s nature is non natural and not empirical. It is what it is. Monism or rather monotheistic man refuse to admit that this is a diabolic treachery. Science based on false assumptions. Science is searching for utopia because monistic people don’t want to admit that pathology is a base of EVERY character. They think that they are good, and that pathology is evil. This MONISTICS fallacy leads to “The ten stages of genocide” by Gregory Stanton. Proper attitude to talk about our psyche should begin – “My pathology which I am not able to cure and then your pathology is incurable also – THIS IS PROPER ATTITUDE. Psyche won’t change just because of monistic claims to it. Psyche is also not a spiritualism or religion. You can not talk about psyche in theological manner, because psyche is not theology. It is politheistic nature of mythic imagination stolen by academic claims. Psychiatry promote the cult of ego, cult of will without inherent psychological influences and thi sis ideological totalitarism. Tabula rasa does not exists. Psychiatry promotes naivety and mental health theory create weak convenient people.

    I expect wisdom and courage and they giving me their useless handkerchief all the time.
    Post Kraepelinians should grow up. Diagnosis is convenient escape from things WE ARE NOT ABLE TO CHANGE. Things that possses ego, things that are more important tha ego will.
    Things That are not personal. Grow up to this. Mental health, apollonian ego people are extremely cowards. Apollonians are a shame for psychological reality. The character of apollonians is based oin things they can buy. That is why people with real identity have nothing in empty reality of things. Materialism is good if we remember who is in charge and this is not Wall Street. This is not psychiatry, and this is not useless medical empiriscism.

    Report comment


    Peter you also may like to watch this video (linked above). I sent a comment on it to Robert Whitaker, click on my name to read it but it is in the comment section under his article on Fernando de Freitas. This video garnered 84,000 views so far. And the comments are all glowing. Worth watching till the end when these men start talking on anxiety and depression and how this repurposed pharmaceutical could be used to stop those. Regulating receptors is spoken of. And so I thought where have I heard this before?

    I am tapering off my antipsychotic with the blessing of my psychiatrist and psychiatric nurse, who have given me the liquid form of abilify. This is the second time I am coming off antipsychotics, the first time I quit cold turkey and had horrible withdrawals for about four months, less severe ones for a year and a half. But I stayed off for three long years. It wasnt easy as my schizophrenia did not go anywhere and so I still had to suffer that. So now I am coming off the antipsychotic freight train the slowly slowly way, tapering incrementally, it will be interesting to me to note if there is going to be a mellower withdrawal process. I doubt it but I hope so. Good to have done it BOTH ways. But yeah, them drugs do nothing for me. That said, I was suicidally distraught when I went back on them.

    Warm wishes to you.

    Report comment

  5. ” It also noted that steroids, birth control pills, and oestrogen-blocking drugs increase the risk of depression but there was no mention that psychiatric drugs, e.g. benzodiazepines, depression pills, and ADHD drugs, can also cause depression,7,8,11,34,44,45 even though this is highly relevant, given their widespread use.”

    With so many illegal and legal drug to indulge in it is quite convenient to ignore these drugs and the drug use and the rise in “instability’ plaguing America. All these psychotropic drugs change brain structure and alter the trajectory of millions of victims. This is just good business for Psychiatry since failure is success as you have patients for life and research that will go on and on forever with little discovered – the ultimate job program.

    Report comment

  6. I am not in the preference to advice, but the story of the colleague berated by being critical and CORRECT moved me. Aware that AIU the colleague was caught off guard, victim of the unexpected and appauling.

    I advise doing the following, how and when to do it, I can not advice:

    1.- When expecting to confront the mental illness is like diabetes, be graphic, carry and show graphs that show something like glucose levels in normal population vs persons with diabetes. Or insulin levels, or something that shows in a graph, an image, how truly different those populations are. Try if possible and useful to ask if psychitric disease have something like that: an objective, i.e. not intersubjective MEASURE of the difference.

    If safe and desirable to be sarcastic provide an image that conveys the difference in “strucutred”, “talk” or clinical psychiatry diagnosis and the technological marble a single high throughput laboratory medicine machine is. Just that word vs “interview” makes my hair dance on its own.

    If situationally adecuate expand on how that machine goes from quantum mechanics to economics, nanothechnology, etc. If sarcasm is due, refer how even people without any knwoledge of what the machine does and how it does it, can nevertheless operate it and get results that are scientifically unimpeachable, most of the time. Sprinkle something like: “Valid in every court in this country”, but it might be a double edge sword.

    If tough crowd mention in passing how psychiatry has to train for years to never, ever approach that level of “technique”. Appear to improvise, like you just seached for at that moment giving the impression it wasn’t difficult at all, a breezeless effort, to use a word play between technique, technology and fraud.

    Compare it to the psychiatrical method: it has the sophisticated technology of the double entry book at best. You can come up with better comparisons, I am sure. Be prolific in research, resourcefullness and imagination. Be graphic and word playfull.

    2.- When confronted with the MI is like cancer, show a chest X-ray of “healthy” people vs one or many with numerous “canon ball” metastasis to the lung. Be prepared and show an MRI of the brain with ADHD and one healthy kid. You can pick them from books, but try that they are almost identical in its position, the slice, along the brain. Beware of copyright issues, give recognition where due.

    If safe explain how even a person without any knwoledge or training in medicine, if appropiate “or psychiatry”, can tell the difference. Try to be jocular about it without spitting on people outside medicine. If already done, compensate and joke about how ignorant some physicians really are, we really are…

    In medical imaging avergaing patients images leads to blurring, but if there was a computer procedure to average without blurring 100 images of healthy people, 100 images of lung metastasis and 100 kids labeled with ADHD that would be terrific. It’s been done for beauty, weight and skin color in females decades or years ago, so technically it’s possible. Mysoginy imaging turned into the fight for safe happy kids…

    You can show one image that conveys the real disease or absence of 100 people with one devastating to the resistance to enlightnment and knowledge movement. To the “obscurantists”.

    3.- Be aware and prepared of the consequences. Graphical wars can lead to shocking imagery of persons with physical injuries caused by persons imputed mental illness, even to themselves. If grossness is not an issue, examples, not images, of physical violence comited by persons under the influence of psychiatric drugs might provide defense. But the point is to raise the conversation, not lower it, particularly not in such close to sewer level.

    And so forth, be creative, be prepared, be graphic and try to be emphatic, a science demolition person. No intellectual ammo should be spared in fighting obscurantism in medicine when it harms minors.

    Be aware and very affraid of the consequences of resisting or fighting obscurantism.

    Hahaha, sarcasm… or not? 🙂
    Twilight zone music…

    Report comment