Psychosis
Schizophrenia: what it is, symptoms and treatment
What schizophrenia is and is not, its main symptoms, how much genes matter, why there is no test, and how it is treated with medication and support.
Schizophrenia is a serious mental disorder that affects perception, thinking and behaviour. Its best-known symptoms are hallucinations, such as hearing “voices”, and delusions. It is not a “split personality”. It is treated with medication and psychosocial support, and its course is not the same for everyone.
What schizophrenia is
The word means “split mind”. It does not mean two personalities in one person. It means that thinking, emotion and the sense of reality lose their coherence.
According to the World Health Organization, schizophrenia affected about 27 million people in 2023, or 1 in 300 [1]. It is slightly more common in men. In men it usually begins in the early to mid twenties. In women it begins a little later, with a second peak of diagnoses in the thirties [8].
What the symptoms are
Specialists group the symptoms like this:
Psychotic symptoms. Hallucinations: you hear or see things other people do not perceive. Delusions: fixed beliefs that do not change with evidence, for example that someone is watching you.
Disorganisation. Thinking and speech jump from topic to topic. Behaviour loses its purpose.
Negative symptoms. Less motivation and energy, withdrawal, flatter expression of emotion. They can look like laziness or like depression.
Cognitive difficulties. With attention, memory and organisation. They can be persistent.
For many people the illness also brings a decline at work, in studies and in relationships.
Is it hereditary?
Genes play a large role, but they are not destiny.
In a Danish study of 31,524 twin pairs, heritability was estimated at 79% [3]. This means genes explain most of the differences in risk between people. It does not mean that 79 out of 100 relatives will become ill.
In the same study, when one identical twin had schizophrenia, the other developed it in 33% of cases. In non-identical twins, in 7% [3]. Since even with the same genes only about 1 in 3 becomes ill, other factors matter too.
There is no single “schizophrenia gene”. The genetic contribution is polygenic: many genes, not one. An international genetic study of 76,755 people with schizophrenia found 287 regions of the genome linked to risk [4].
Factors around birth and early life also play a part. Cannabis is widely discussed. In a meta-analysis of 66,816 people, the heaviest users had about four times the odds of schizophrenia or another psychosis compared with non-users [5]. Cause and effect has not been proven conclusively, but the more cannabis, the higher the risk.
Is there a test for schizophrenia?
No. No blood test, scan or online questionnaire makes the diagnosis. A psychiatrist makes it, through interview, history and follow-up over time. The diagnostic criteria require signs of the illness to last continuously for at least six months [8].
Tests have a different job: they rule out other causes. Tests are done to rule out substance use. A CT or MRI scan of the brain is done when a tumour or another neurological condition needs to be ruled out [8].
A diagnosis of schizophrenia is not made in a hurry. A full assessment comes first, so that the diagnosis guides the treatment. Whether this is schizophrenia, a substance-induced psychosis or a mood disorder changes the treatment plan from the start.
How it is treated
Medication. Antipsychotic medication remains the basis of treatment. In an analysis of 65 studies with 6,493 patients who had been stabilised, those who continued treatment relapsed within a year in 27% of cases, compared with 64% of those given placebo. They also had fewer episodes of aggression (2% compared with 12%), although the data on this were limited [6].
Medication has side effects too. In the same analysis, weight gain (10% compared with 6%), movement side effects (16% compared with 9%) and sleepiness (13% compared with 9%) were more common [6]. That is why the UK NICE guideline asks, before treatment starts, for weight, waist, pulse and blood pressure to be measured, and for tests of blood sugar, lipids and prolactin. Blood sugar and lipids are checked again at 12 weeks, at one year and then every year [7].
The same guideline says that the patient and the doctor choose the medication together. If the illness has not responded well enough to two different antipsychotics, each tried properly one after the other, it recommends clozapine [7].
We make the decision about medication together. We discuss the alternatives, the possible side effects and how long it should take for the benefit to show. From the start we agree an “if… then…” plan: what we change if a side effect appears or if improvement is slow.
When I hear that “no medication has worked”, I first check whether the earlier trials were at an adequate dose and for long enough, and whether the medication was taken regularly. Only then do we speak of treatment-resistant illness.
Psychological and social support. The NICE guideline recommends cognitive behavioural therapy for everyone with psychosis or schizophrenia, one to one and over at least 16 sessions, as well as family intervention [7]. According to a recent review, the effect of cognitive behavioural therapy on the symptoms themselves is relatively small [2]. The guideline also recommends supported employment programmes for people who want to find work or return to it [7].
Physical health. According to the WHO, people with schizophrenia die on average nine years earlier than the general population [1]. Regular checks of weight, blood sugar and blood pressure are part of treatment, not an afterthought.
Three myths
“It is a split personality.” No. Schizophrenia is about contact with reality, not about having two personalities.
“People with schizophrenia are dangerous.” The risk of violent behaviour is only slightly increased. Threats and minor outbursts are far more common than serious violence [8].
“Nothing can be done.” The course is not uniformly poor. There are treatments that reduce relapses and programmes that help people return to work.
When to ask for help
You hear or see things other people do not perceive.
You have become convinced that people are watching you or want to harm you, and those close to you are worried.
Someone you love is withdrawing, their performance is dropping and their speech is becoming confused.
The symptoms started after using cannabis or other substances.
You already have a diagnosis and want your treatment reviewed or a second opinion.
Safety: If there is a risk to the person or to others, call 166 (ambulance, EKAV) or 112, or go to the emergency department of the hospital on duty. If there are thoughts of suicide, you can also call the Suicide Prevention Line 1018.
How I can help
Book an appointment for a psychiatric assessment, at the practice in Trikala or online. The page schizophrenia and psychosis describes how assessment and follow-up work. For follow-up sessions and for conversations with the family, see how working with an online psychiatrist works. If you are not sure which specialist to see, read psychiatrist or psychologist in Greece. For psychosis from any cause, read psychosis and the first psychotic episode, or book an appointment.
This article is educational and does not replace individual clinical assessment. Do not change or stop any treatment you are already taking without talking to your doctor.
Sources
World Health Organization. Mental disorders. Fact sheet, 11 September 2026. https://www.who.int/news-room/fact-sheets/detail/mental-disorders
Jauhar S, Johnstone M, McKenna PJ. Schizophrenia. Lancet. 2022. https://doi.org/10.1016/S0140-6736(21)01730-X
Hilker R, et al. Heritability of Schizophrenia and Schizophrenia Spectrum Based on the Nationwide Danish Twin Register. Biol Psychiatry. 2018. https://doi.org/10.1016/j.biopsych.2017.08.017
Trubetskoy V, et al. Mapping genomic loci implicates genes and synaptic biology in schizophrenia. Nature. 2022. https://doi.org/10.1038/s41586-022-04434-5
Marconi A, et al. Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis. Schizophr Bull. 2016. https://doi.org/10.1093/schbul/sbw003
Leucht S, et al. Antipsychotic drugs versus placebo for relapse prevention in schizophrenia: a systematic review and meta-analysis. Lancet. 2012. https://doi.org/10.1016/S0140-6736(12)60239-6
NICE. Psychosis and schizophrenia in adults: prevention and management (CG178). 2014, with later updates. https://www.nice.org.uk/guidance/cg178
Keshavan MS. Schizophrenia. MSD Manual, Consumer Version. Last updated February 2026. https://www.msdmanuals.com/home/mental-health-disorders/schizophrenia-and-related-disorders/schizophrenia
