Schizophrenia is a type of mental health condition that causes many symptoms including hallucinations. A hallucination is a term used to refer to seeing, hearing, or smelling something that does not actually exist. It happens when you receive certain sensory information that is not there and it is basically a disturbance in perception that is created by the brain.
Hallucinations are known to affect any of the five senses, which means that it is possible to see, hear, feel, smell, or taste something that does not exist and that no one else can sense. Here’s everything that you need to know about hallucinations and schizophrenia.
What is Schizophrenia?
Schizophrenia is a type of serious mental health disorder that causes people to interpret their reality in an abnormal manner. This disorder often causes a combination of hallucinations, delusions, and even severe disordered behavior and thinking that disrupts their day-to-day functioning. Schizophrenia can be a disabling condition and people who have this condition need to undergo lifelong treatment. Seeking early treatment for schizophrenia can help bring the symptoms under control before any serious complications develop. This may also help improve the long-term outlook of people living with schizophrenia.(1,2,3,4)
Schizophrenia causes a wide range of problems with behavior, cognition, or thinking, as well as emotions. The signs and symptoms of the disorder vary from person to person but typically involve hallucinations, delusions, disorganized speech, and having an impaired ability to function in their day-to-day life.
Schizophrenia and Hallucinations
Hallucinations in schizophrenia usually involve hearing or seeing things that are not there. However, for the person with schizophrenia, hallucinations happen with full force and frequently impact their normal experience. Hallucinations can take place in any of the five senses, but hearing voices is one of the most common forms of hallucination that occurs in people with schizophrenia.(5,6)
In the past, there was quite a lot of debate on the fact that people with schizophrenia automatically experience hallucinations. While it is true that many people who have schizophrenia do experience hallucinations, it is not true that every person with schizophrenia experienced hallucinations. Research dating back to 2010 estimated that nearly 70 percent of people diagnosed with schizophrenia have hallucinations.(7)
Schizophrenia does not always occur with hallucinations. At the same time, a person having schizophrenia may experience hallucinations for many other reasons as well. It is important, therefore, to understand that hallucinating does not automatically translate to mean you have schizophrenia.
Types of Schizophrenia Symptoms and Hallucinations
As a mental health disorder, schizophrenia typically involves the symptoms of psychosis, which causes disruption to the manner in which the brain processes various information. This causes a disconnect from reality.
The symptoms of schizophrenia are primarily divided into three main types. These include:(8,9)
- Positive Symptoms – known as the presence of feelings, perceptions, and behaviors that you would not usually experience.
- Negative Symptoms – known as a decline in emotions, thoughts, and behavior that you would normally experience.
- Disorganized Symptoms – known as a state of confusion and disruption in your speech, movements, thoughts, and behavior.
When it comes to hallucinations, they are grouped into the category of positive schizophrenia symptoms. Hallucination can, in theory, affect any of the five senses. They may include:
- Auditory hallucinations, which are the most common in schizophrenia and refer to things that a person can hear, including voices, music, or bells ringing.(10)
- Visual hallucinations, which are the second most common type of hallucinations in people with schizophrenia. These refer to things that a person can see such as distorted images, demons, or even loved ones who are dead.(11)
- Tactile hallucinations, which refer to things that a person can feel including the sensation of something slithering across their skin or feeling a hand on their shoulder.(12)
- Olfactory hallucinations, which refer to things a person can smell. These can be both foul and nice odors, or they may even smell something burning while there is nothing of that sort happening.(13)
- Gustatory hallucinations, which refer to things that can be tasted. People experience tasting something bitter or metallic on their tongue or in their throat as part of the hallucination.(14)
Throughout the years, studies have consistently shown that auditory hallucinations are the most common type of symptom experienced in people with schizophrenia. According to a study done in 2021, nearly 60 to 80 percent of people who are living with schizophrenia spectrum disorder often hear sounds that other people are unable to hear, including people speaking a language that others don’t recognize, music, or the voice of a loved one.(15)
Visual hallucinations are also common in people with schizophrenia, though it is not as common as auditory hallucinations. As referenced above, the study done in 2010 showed that some people see surreal things like body parts, distorted people, objects superimposed on real people, strange and unusual objects that they are unable to identify. Many people also see things like demons, lights, or strange animals.(7)
On the other hand, gustatory, tactile, and olfactory hallucinations happen quite rarely. Though older studies have found a strong association between these types of hallucinations. One study noted that if you experience any one type of hallucination, you become more likely to experience the others as well. And in fact, you may even experience these hallucinations as the early signs and symptoms of schizophrenia.(6)
Hallucinations in schizophrenia patients can even be multimodal. This means that they may involve one or more than one of the senses. There is some evidence to show that multimodal hallucinations are actually the most common type of hallucinations experienced in people with schizophrenia. A study in 2016 that looked at data from nearly 750 people with schizophrenia found the following:(16)
- Nearly 80 percent of the participants experienced some form of hallucination.
- Over 50 percent of the participants experienced multimodal hallucinations.
- Nearly 27 percent of the participants experienced unimodal hallucinations or hallucinations that involved only one of their senses.
Is It Possible To Have Schizophrenia Without Hallucinations?
Even though quite a few people who have schizophrenia experience some form of hallucination at some point in their life, it is also possible to have schizophrenia without experiencing any hallucinations. In order to be diagnosed with schizophrenia, you have to experience at least two out of five main symptoms on most days for a period of at least one month. These five main symptoms include:
- Hallucinations
- Difficulty expressing emotions and experiencing any interest or joy in life.
- Having confused or disorganized speech.
- Delusions
- Catatonia, or unusual/disorganized movements and gestures
While there are five major symptoms that doctors look out for, in most cases, at least one of the two symptoms to confirm the diagnosis of schizophrenia should be hallucinations, confused and disorganized speech, or delusions. This means that even if you do not experience any hallucinations, but you experience delusions and other symptoms of schizophrenia, you could be diagnosed with schizophrenia.(17,18,19)
Causes of Hallucinations
Medical experts are still not completely sure about what exactly causes hallucinations in people with schizophrenia or in other people who have some other condition. Some of the current theories typically associate hallucinations with spontaneous activation of certain parts of the brain.(20) These random activations are believed to trigger certain sensory details that are usually linked with the hallucination, such as the images, sensations, or the sounds that no one else notices.
Many brain imaging studies have also shown that people with schizophrenia tend to have higher activity levels in certain parts of their brains, especially the hypothalamus and the paralimbic regions. At the same time, they also have reduced activity in other parts, such as the temporal lobes.(21)
Experts have also discovered that people who have conditions that typically give rise to symptoms of psychosis tend to have decreased gray matter in certain parts of the brain.(22)
There is also evidence to show that the neurotransmitter dopamine also has a part to play in the occurrence of hallucinations. Studies have linked the positive symptoms of psychosis, such as hallucinations, to the presence of high levels of dopamine in the mesolimbic pathway.(22) Studies from 2019 have shown that dopamine imbalances in the nigrostriatal pathway can also have a role to play in the development of hallucinations. The nigrostriatal pathway is important for regulating motor function in the body.(23)
Hallucinations are most probably linked with certain irregularities in brain structure, chemistry, and processing. They are also more common than you would think. In fact, apart from schizophrenia, there are many other conditions where it is possible to experience hallucinations as a symptom. These may include:
- Bipolar disorder
- Major depression with psychotic features
- Extreme stress or grief
- Postpartum psychosis
- Migraine
- A high fever
- Progressive neurological conditions such as Alzheimer’s disease and Parkinson’s disease
- Sleep deprivation
- Hearing or vision loss
- Seizures
Of course, taking any type of hallucinogenic drug can also cause hallucinations. Drinking heavily or alcohol withdrawal can also lead to hallucinations.(24)
Conclusion
If you have been diagnosed with schizophrenia and you experience hallucinations, letting your doctor know will help them begin the right treatment to help you. The important thing to be aware of is that schizophrenia does not tend to improve on its own without treatment. At the same time, hallucinations can also be a symptom of other underlying conditions. Your doctor will help identify the possible causes of hallucinations and offer guidance on what would be the best approach to treatment.
- Insel, T.R., 2010. Rethinking schizophrenia. Nature, 468(7321), pp.187-193.
- McCutcheon, R.A., Marques, T.R. and Howes, O.D., 2020. Schizophrenia—an overview. JAMA psychiatry, 77(2), pp.201-210.
- Van Os, J., Kenis, G. and Rutten, B.P., 2010. The environment and schizophrenia. Nature, 468(7321), pp.203-212.
- Gottesman, I.I., Shields, J. and Hanson, D.R., 1982. Schizophrenia. CUP Archive.
- Bentall, R.P., 1990. The illusion of reality: a review and integration of psychological research on hallucinations. Psychological bulletin, 107(1), p.82.
- Mueser, K.T., Bellack, A.S. and Brady, E.U., 1990. Hallucinations in schizophrenia. Acta Psychiatrica Scandinavica, 82(1), pp.26-29.
- Chaudhury, S., 2010. Hallucinations: Clinical aspects and management. Industrial psychiatry journal, 19(1), p.5.
- Andreasen, N.C. and Flaum, M., 1991. Schizophrenia: the characteristic symptoms. Schizophrenia bulletin, 17(1), pp.27-49.
- Gross, G., 1989. The ‘basic’ symptoms of schizophrenia. The British Journal of Psychiatry, 155(S7), pp.21-25.
- Blom, J.D., 2015. Auditory hallucinations. Handbook of clinical neurology, 129, pp.433-455.
- Teeple, R.C., Caplan, J.P. and Stern, T.A., 2009. Visual hallucinations: differential diagnosis and treatment. Primary care companion to the Journal of clinical psychiatry, 11(1), p.26.
- Berrios, G.E., 1982. Tactile hallucinations: conceptual and historical aspects. Journal of Neurology, Neurosurgery & Psychiatry, 45(4), pp.285-293.
- Kopala, L.C., Good, K.P. and Honer, W.G., 1994. Olfactory hallucinations and olfactory identification ability in patients with schizophrenia and other psychiatric disorders. Schizophrenia research, 12(3), pp.205-211.
- Lewandowski, K.E., DePaola, J., Camsari, G.B., Cohen, B.M. and Ongur, D., 2009. Tactile, olfactory, and gustatory hallucinations in psychotic disorders: a descriptive study. Ann Acad Med Singapore, 38(5), pp.383-385.
- Hare, S.M., 2021. Hallucinations: A Functional Network Model of How Sensory Representations Become Selected for Conscious Awareness in Schizophrenia. Frontiers in Neuroscience, 15, p.733038.
- Lim, A., Hoek, H.W., Deen, M.L., Blom, J.D., Bruggeman, R., Cahn, W., de Haan, L., Kahn, R.S., Meijer, C.J., Myin-Germeys, I. and van Os, J., 2016. Prevalence and classification of hallucinations in multiple sensory modalities in schizophrenia spectrum disorders. Schizophrenia research, 176(2-3), pp.493-499.
- Tsuang, M.T., Stone, W.S. and Faraone, S.V., 2000. Toward reformulating the diagnosis of schizophrenia. American Journal of Psychiatry, 157(7), pp.1041-1050.
- Andreasen, N.C., 1987. The diagnosis of schizophrenia. Schizophrenia bulletin, 13(1), pp.9-22.
- Andreasen, N., 1995. Symptoms, signs, and diagnosis of schizophrenia. The Lancet, 346(8973), pp.477-481.
- Hare, S.M., 2021. Hallucinations: A Functional Network Model of How Sensory Representations Become Selected for Conscious Awareness in Schizophrenia. Frontiers in Neuroscience, 15, p.733038.
- Thakur, T. and Gupta, V., 2020. Auditory Hallucinations.
- Calabrese, J. and Al Khalili, Y., 2019. Psychosis.
- McCutcheon, R.A., Abi-Dargham, A. and Howes, O.D., 2019. Schizophrenia, dopamine and the striatum: from biology to symptoms. Trends in neurosciences, 42(3), pp.205-220.
- Waters, F. and Fernyhough, C., 2017. Hallucinations: a systematic review of points of similarity and difference across diagnostic classes. Schizophrenia bulletin, 43(1), pp.32-43.
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