Symptoms of schizophrenia: what to look out for

Schizophrenia is a serious mental health disorder, that affects thought processes, the senses, perception of reality and a person’s behaviour¹. Schizophrenia comes with psychosis¹, which essentially entails being more or less out of touch with reality and the serious deterioration of one’s personal, occupational and social life². It is diagnosed after the first psychotic episode which varies in length from a few hours to a few months³. During such episodes, a person may experience hallucinations or an altered perception of the environment or of reality². Through diagnosis and early intervention, the symptoms of schizophrenia lessen or disappear in many individuals. Nevertheless, some patients keep regressing with new psychotic episodes or persistent symptoms⁴. The disease is widely surrounded by stigma and misconceptions⁴.  

Common symptoms of schizophrenia and diagnosis

Schizophrenia symptoms may vary. For instance, the individual might hear voices or see things that others do not, have altered sensory perception or altered understanding of his or her surrounding environment.

To make a diagnosis at least two of the following symptoms must appear, and at least one of them must be in the top three on the list⁵:

1. delusions
2. hallucinations
3. disorganized speech (like derailment or incoherence)
4. grossly disorganised or catatonic behaviour, causing immobility, stiffness and unresponsiveness to stimuli
5. Negative symptoms, that is, a decline in the individual’s normal functioning, like speaking a lot less⁵.

Moreover, symptoms must last for at least six months and must manifest themselves for the greater part of at least one month⁵.

Early symptoms of schizophrenia

Some cognitive, emotional or perception changes may emerge weeks, months or even years prior to the first psychotic episode that leads to the diagnosis⁶. Specifically, the first signs of schizophrenia can appear in adolescence⁶. They may include anxiety, depression, social isolation, failing at school or work, changes in sleep patterns, apathy and unusual behaviours or thoughts⁶. The individual may seem introverted, disorganised or suspicious⁶. These signs also overlap with other mental health disorders, so it is not easy to draw a link with the disease, although it may be important⁶. Specialists need to perform close observation without underestimating the disorders and without alarming the patient if possible⁶ – reminding them that schizophrenia is less common than other mental health diseases⁷. In general, optimally treating the disorder in a timely manner can lower the risk of the disease or delay the onset of psychosis in some cases⁶.

Delusions and hallucinations

Hallucinations and delusions are common symptoms of schizophrenia⁵. Hallucinations are sensory experiences in the absence of existing stimuli, and can involve sight, hearing, smell, touch and taste – the most frequent are auditory ones⁸. Delusions are fixed and unrealistic beliefs that are extremely implausible and firmly held of despite evidence to the contrary^5,8.
The person may also have incoherent and disorganized thinking or believe that others are reading their thoughts or that thoughts are introduced from the outside and not produced by the mind⁵. Paranoia is the most common delusion in individuals with schizophrenia⁹. They may mistakenly feel that they are being persecuted, followed, spied on, threatened or poisoned, often even by a relative or friend⁸. They may attach groundless meanings to things that happen or develop delusional convictions to explain the hallucinations they suffer from⁸. For example, if they hear voices that describe their actions, they might feel followed or watched. The paranoia may lead to social impairment or isolation⁸.

Symptoms of schizophrenia in adults: what to look out for

Symptoms often show up in early adulthood, when one begins to define life and become independent⁴. That is exactly why this disease can interfere with work and familial/social relations, and thus, with self-realisation⁴. The first few years following diagnosis are those when the risk of suicide is at its peak⁴. Not to mention that some individuals may have a hard time maintaining a healthy diet, proper hygiene or a regular sleep schedule¹⁰. The related stigma is very widespread, and among adults may cause social exclusion or a violation of the individual’s rights in the community or at care facilities⁷.

Given such a complex picture, timely and accurate treatment is essential, and can greatly reduce symptoms and the risk of regression⁴.

References:

1. National Institutes of Health (Nimh – NIH, Usa), “Schizophrenia”, December 2024
2. National Institutes of Health (Nimh – NIH, Usa), “Understanding psychosis”
3. Healthdirect (AU), “Psychosis”, May 2023
4. National Institute for Health and Care Excellence (NICE, Uk), “Psychosis and schizophrenia in adults: prevention and management”. London, 2014 Mar. (NICE Clinical Guidelines, No. 178). Available from: https://www.ncbi.nlm.nih.gov/books/NBK555203/
5. Hany M., Rehman B., Rizvi A., et al., “Schizophrenia”. [Updated 2024 Feb 23]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539864/
6. Larson M. K., Walker E. F., Compton M. T., “Early signs, diagnosis and therapeutics of the prodromal phase of schizophrenia and related psychotic disorders”. Expert Rev Neurother. 2010 Aug;10(8):1347-59. doi: 10.1586/ern.10.93. PMID: 20662758; PMCID: PMC2930984, https://pmc.ncbi.nlm.nih.gov/articles/PMC2930984/
7. World Health Organization (WHO), “Schizophrenia”, 10 January 2022
8. National Health Service (NHS, Uk), “Symptoms – Schizophrenia”, 13 April 2023
9. Pinkham A. E., Harvey P. D., Penn D.L., “Paranoid individuals with schizophrenia show greater social cognitive bias and worse social functioning than non-paranoid individuals with schizophrenia”. Schizophr Res Cogn. 2016 Mar;3:33-38. doi: 10.1016/j.scog.2015.11.002. Epub 2016 Jan 13. PMID: 27990352; PMCID: PMC5156478, https://pmc.ncbi.nlm.nih.gov/articles/PMC5156478/
10. Psykiatri og Social, “Information about Schizophrenia in adults. The disorder, its treatment and prevention”, psykinfomidt.dk, Version 1.03.2019, https://www.psykiatrien.rm.dk/contentassets/06b3f024ec9947188cc40582307623d3/80187-pjece-om-skizofreni-hos-voksne-1.03_uk_web.pdf