I will say this, its a disorder that can have multiple causes, and often misdiagnosed because its thrown out over other illnesses. Its also a good way of also labeling people who see more than others, the big imaginative thinkers.
People constantly look for the cause of schizophrenia, and are constantly coming up with different causes and etiological theories. My thoughts are a lot of them are right even though they can contradict one another; the diagnostic criteria simply lists symptoms that can apply to a number of psychological, genetic and neurological conditions that can cause the symptoms that then get labeled schizophrenia.
A few causes:
1. Psychological trauma. IMO, 95% of people who are mentally ill displaying symptoms that dont seem to have an organic origin (such as a tumor or dementia) have it from psychological trauma, primarily in early childhood. This is by far the most misunderstood and ignored part in psychiatry. Its also difficult to grasp, but from everything I have witnessed, enough trauma can turn a healthy person into a schizophrenic. I know, goes against what every psychiatrist was taught in school, but its true. The more sever the trauma the more server of a psychiatric illness you will have. Psychotic symptoms result and are at the severe end of the abuse spectrum.
Psychological trauma profoundly (I am very far from useing that term lightly) changes the way the developing mind processes information. It forces dissociation, and grooms the brain to use imagination to cope with pain. The same survival mechanism in child hood latter becomes the illness. It would explain why schizophrenics hallucinate because at one point it was necessary to invest vast neurological energy to super impose powerful feelings/thoughts/perceptions over the reality being perceived. The mind wires itself to be based on internal stimulation, because at that time external stimulation was to much to handle and for an exceptionally good reason. To put it bluntly the average person can separate reality from fantasy, in a schizophrenic the mechanism damaged or under developed so to speak by the environment. A childs brain is plastic par excellence, so its a perfectly plausible theory to those that doubt it. Nearlly everyone who I have known who was mentally ill and I mean almost everyone had an extensive history of childhood trauma. One of the best quotes I have heard (forget the name) was from a famous psychiatrist who said "psychosis is an sane reaction to an insane problem"
Eugene Bleuler who made the term schizophrenia had supicions it was caused by childhood trauma.
2. Adding to the top, undiagnosed trauma disorders: Dissociative, complex PTSD, BPD, ect.
Trauma disorders especially dissociative disorders share a whopping amount of symptoms to psychotic disorders, but its not something widely know to psychiatrists. Probably because psychiatrists are taught dissociative disorders are rare, so rare dont worry about it. PTSD isnt as graphic either. Sooo... anyone who displays symptoms from a trauma disorder will automatically be labelled as schizophrenic or psychotic further reinforcing the belief trauma disorders are rare. Its all from the influence from the pharmaceutical industries who push the chemical imbalance theory as the driver of mental disorders because it easily gives nearly every single psychiatric illness drugs to use. Bipolar, ADHD, schizophrenia, whether real or not, chemical imbalance or not one thing is real: Every time a psychiatrist make a diagnosis of schizophrenia/bipolar/ADHD its drugs al carte for the patient which means another financial score for the pharmaceutical industries. So any influence by big pharma will be to get any and all symptoms under disorders like schizophrenia which are predominately drug treatable unlike Dissociative disorders or PTSD. Add to the fact Dissociative disorders and PTSD are treatable, having a person get a schizophrenic label over what they really have means they the patient will never recover and take drugs for life since they both have a misdiagnosis and doctors are told schizophrenia is not curable thus requiring drugs for life.
Truth is DID in particular has more Schneiderian first rank symptoms than schizophrenia. And anyone who tells a classical psychiatrist 'I hear voices talking in my head with each other or to me' and 'I believe I have alternate personalities' will automatically bing 2 points for schizophrenia: 1. hearing voices and 2. the delusion other live in you. Both of which are perfectly normal for DID but also fit the schizophrenia criteria. DID also dissociative amnesia, fugue ect have symptoms very similar to the negative aspect symptoms in schizophrenia. Dissociative disorder patient are also highly hypnotizable making them very suseptable to delusional thoughts or fayning schizophrenia because its what the psychiatrist might be looking for. Flash backs of abuse can cause the patient to feel paranoid or unsafe, but that often gets labelled a delusion as well. Rapid switching or a very dissociated patient may also do poorly on reality testing further increasing the chance of the schizophrenic diagnosis. There are other that overlap well but to keep it short those are some of the biggest.
3. Sleep disturbances: I have come across this theory more than once that a patient who has difficulty staying in REM sleep or isnt getting enough of it can develop frank psychotic symptoms. Some schizophrenics report not being able to sleep before a major psychotic episode. Its possible that if the mechanism of REM sleep is broken or the brain is so deprived of it that while awake the person goes into REM. The brain is essentially awake but in REM. The REM being triggered while awake and conscious can certainly explain the florid hallucinations. A lot of schizophrenics call it being like in a dream but awake.
4. Pseudo seizures: Supposedly complex undiagnosed seizures can cause alterations in perceptions and reality processing. Its another proposed explanation out of many.
5. Electro magnetic hypersensitivity disorder. I hear its recognized in Sweden? EMFs from cell phones, electricity, ect bother those who are suseptable to it. A lot of it is debated since its unknown how non ionizing radiation truly effects the body. But its nothing I don't close my mind off to.
6. Fetal growth: this branches off into a lot of different sub theories. Supposedly virusius during pregnancy, cerebral atrophy, fetal drug exposure ect change the brain or inflict brain damage.
7. Heavy metal poisoning. This is a bigger problem then most people want to admit, and most psychs don't do this test. IMO it should be routine as drug prescriptions in psychiatry. Its well enough documented exposure to lead, mercury, arsenic ect which are all classified as neuro toxins and can produce delirium, hallucinations, flat effects, aggression (especially lead in children), lethargicness, catatonic stupors... almost every symptom of schizophrenia. And of course in a case like this psychiatric medications will do nothing but harm the patient more.
8. Dopamine hypothesis of schizophrenia. I believe its real, it has been proven with spinal taps and medications that target the believed mechanism of action reliving the symptoms. But I do not believe its as common as its made out to be.
9. Genetics. This gets complex, Google is better at explaining it then me.
10. Inborn cognitive deficits which effect reality processing or the way information is stored.
11. The chemical imbalance theory. Should be also number 8 since its part of it. Its this theory that is the most researched, most beloved, advanced upon and IMO full of the most misunderstandings. Its is heavily pushed by big pharma hence funded by universities. Every psychiatry student is flooded with the chemical imbalance theory and its spin offs a lot of which is nothing more than a theory. Reading up on the chemical imbalance theory may make you feel smart since its incredibly complex, but its heavily influenced by big pharma because it creates the perception that there is a scientific validation and bases for the mass drugging of people

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