Psychotic behaviour represents a profound shift in how a person perceives and interacts with the world around them. When someone experiences psychosis, the boundary between what is real and what is not becomes blurred, leading to a range of symptoms that can be deeply distressing for both the individual and those around them. Understanding this condition is the first step toward recognizing when someone needs help and ensuring they receive appropriate care.

How Common Is Psychotic Behaviour

Psychotic behaviour affects more people than many realize. Studies suggest that approximately three in every 100 people will experience a psychotic episode at some point during their lifetime.^[11] In any given 12-month period, fewer than one in every 200 adult Australians will experience a psychotic illness.^[6] This means that nearly 11,300,000 American people could be affected—more than the entire population of Greece.^[18]

The first episode of psychosis typically occurs during late adolescence or early adulthood, with most people experiencing their first symptoms between the ages of 16 and 35.^[3] Approximately 1,600 new cases of psychosis are reported in Scotland every year.^[19] These numbers highlight that psychotic behaviour is not a rare occurrence, and many people either personally experience it or know someone who does.

The duration and frequency of psychotic episodes vary significantly from person to person. Some individuals may experience symptoms that last only a day, while others may have episodes lasting weeks, months, or even longer.^[11] Some people experience only a few brief episodes throughout their lives, while others may have more frequent occurrences associated with longer-term mental health conditions.

What Causes Psychotic Behaviour

Psychotic behaviour is not a disease in itself but rather a collection of symptoms that can arise from many different underlying conditions. It’s sometimes helpful to think of a psychotic episode as you would a fever—it’s a signal that something is wrong with the body or brain, but it requires medical evaluation to determine the specific cause.^[11]

Several mental health conditions commonly feature psychotic symptoms. Schizophrenia, which is a serious psychiatric condition causing a range of psychological symptoms including hallucinations and delusions, is one of the primary conditions associated with psychosis.^[3] People with bipolar disorder, a mental health condition affecting mood with episodes of depression and elated mood called mania, may also experience psychotic symptoms.^[3] Additionally, some people with severe depression have symptoms of psychosis when they are very depressed.^[3]

Beyond mental health conditions, various physical illnesses can trigger psychotic behaviour. Brain-related conditions such as Alzheimer’s disease and other forms of dementia—conditions causing progressive decline in memory and thinking—can cause psychosis.^[4] Brain tumours, infections of the brain or spinal cord like encephalitis (brain inflammation) or meningitis (inflammation of the membranes surrounding the brain and spinal cord), stroke, and head injuries can all lead to psychotic symptoms.^[3,4]

Hormone-related conditions also play a role. Disorders affecting the thyroid gland, Addison’s disease, and Cushing’s disease can all cause psychosis.^[4] Vitamin deficiencies, particularly of vitamin B1 (thiamine) and vitamin B12, have been linked to psychotic symptoms.^[4] Other conditions including lupus, Lyme disease, and multiple sclerosis can also be responsible.^[4]

Substance use is another significant cause of psychotic behaviour. Drug misuse, alcohol misuse, and even side effects from prescribed medications can trigger psychosis.^[3] The use of substances such as cannabis, cocaine, or amphetamines can cause psychotic episodes.^[11] Stopping drug or alcohol use suddenly after prolonged consumption can also lead to psychosis.^[19]

Finally, traumatic experiences, severe stress, and childbirth can all trigger psychotic episodes. Postpartum psychosis is a rare but severe mental health emergency related to postpartum depression that can occur after giving birth.^[4]

Who Is At Greater Risk

While psychosis can happen to anyone, certain groups of people face higher risk. Having a family member or relative with psychosis increases the likelihood of developing the condition yourself, suggesting a genetic component to vulnerability.^[19]

Young people between their mid-teens and mid-thirties are at particular risk, as this is the age range when first episodes most commonly occur.^[3,11] Studies have shown that childhood trauma, especially sexual and physical abuse along with emotional abuse and neglect, significantly increases the risk for later development of psychotic symptoms.^[19]

People experiencing intense stress, bereavement, or traumatic events are more vulnerable to developing psychotic episodes.^[4,19] Those with existing mental health conditions such as schizophrenia, bipolar disorder, or severe depression face ongoing risk of experiencing psychotic symptoms.^[3,4]

Individuals who misuse alcohol or drugs, particularly substances like cannabis, cocaine, and amphetamines, have a substantially elevated risk of experiencing psychosis.^[3,11] People with certain physical health conditions affecting the brain, such as Parkinson’s disease or Alzheimer’s disease, are also at increased risk.^[11]

Recognizing The Symptoms

Psychotic behaviour manifests through several distinct types of symptoms that affect how a person thinks, perceives the world, speaks, and behaves. Understanding these symptoms can help in recognizing when someone may need medical attention.

The three main symptoms associated with psychosis are hallucinations, delusions, and confused or disorganized thinking and speaking.^[3] Hallucinations occur when parts of the brain mistakenly act as if the senses have picked up on something that isn’t actually happening.^[4] A person might hear voices speaking to them when no one is there—this is called an auditory hallucination and is one of the most common forms.^[3] They might also see people, colors, or shapes that don’t exist, feel someone touching them when alone, smell odours others cannot detect, or taste things despite having nothing in their mouth.^[7]

Delusions are false beliefs that someone holds onto very strongly, even when others don’t believe them or when there’s plenty of evidence that the belief isn’t true.^[4] Common types include paranoid delusions, where a person believes they are being watched, followed, or that someone is plotting to harm them.^[3,6] Some people develop grandiose delusions, believing they have special powers, are important religious or political figures, or have extraordinary abilities.^[6] Others experience delusions of control, believing that external forces such as aliens or invented groups are controlling their thoughts or actions.^[6]

Confused and disturbed thinking affects how a person processes and expresses thoughts. Their ideas may come very quickly, making their speech fast and confusing.^[3] They might speak very rapidly or very slowly, switch topics frequently mid-conversation, speak in muddled-up sentences, use wrong words to describe things, or even make up words.^[6] There may be sudden interruptions in their train of thought, resulting in abrupt pauses in conversation or activity.^[7]

Beyond these core symptoms, psychotic behaviour often involves changes in behaviour and feelings. People may withdraw from family and friends, experience changes in sleep patterns such as sleeping during the day and staying awake at night, have changes in appetite, or show decreased attention to personal hygiene.^[18] They might engage in behaviours that seem strange or uncharacteristic, display incoherent or bizarre speech or writing, or experience a dramatic drop in their ability to function at work or school.^[18]

Emotionally, people experiencing psychosis may feel disconnected from reality, out of control, frightened for no apparent reason, unable to focus or remember things, or as if something is happening to their thoughts.^[18] The combination of hallucinations and delusional thinking can cause severe distress and significant changes in behaviour.^[3]

Prevention Strategies

While it may not always be possible to prevent psychotic behaviour entirely, certain measures can reduce risk or delay onset of symptoms, particularly for those with known risk factors.

Early intervention is crucial. Getting immediate medical help at the first signs of psychotic symptoms can make a significant difference in outcomes.^[3,11] Studies have shown that early diagnosis and treatment improve long-term prognosis and may reduce the severity and duration of episodes.^[11]

Avoiding substance misuse is one of the most important preventive measures. Steering clear of recreational drugs such as cannabis, cocaine, and amphetamines significantly reduces the risk of drug-induced psychosis.^[3,11] If someone already uses alcohol or drugs regularly, avoiding sudden cessation without medical supervision is important, as withdrawal can trigger psychotic symptoms.^[19]

Managing stress and addressing trauma can help reduce risk. Learning healthy coping mechanisms for stress, seeking support after traumatic experiences, and addressing past trauma through counseling or therapy may lower vulnerability to psychotic episodes.^[19]

For individuals with known mental health conditions associated with psychosis, such as schizophrenia or bipolar disorder, maintaining consistent treatment is essential. Taking medications as prescribed, attending regular appointments with mental health professionals, and following treatment plans can prevent or reduce the frequency of psychotic episodes.^[3]

If someone has a family history of psychosis or other risk factors, awareness and education about warning signs can help ensure prompt recognition and treatment. Teaching family members, teachers, college counselors, school nurses, and healthcare providers to recognize early signs of psychosis can lead to earlier intervention.^[11]

How Psychosis Affects The Body And Mind

Understanding what happens in the brain and body during psychosis helps explain why symptoms occur and how they affect daily functioning.

During psychosis, there are disruptions in how the brain processes thoughts and interprets sensory information. Research suggests that neurotransmitters—chemical messengers in the brain that transmit signals between nerve cells—play a significant role.^[8] One neurotransmitter called dopamine appears particularly important in psychotic symptoms. Antipsychotic medications work primarily by blocking the effect of dopamine in the brain.^[8]

The brain regions involved in processing sensory information and forming perceptions become disrupted during psychosis. This disruption causes the brain to generate false sensory experiences—hallucinations—where parts of the brain act as if the senses have detected something real when nothing external has actually stimulated them.^[4] For example, the auditory processing centers might activate and create the experience of hearing voices, even though no sound waves have entered the ears.

The areas of the brain responsible for reasoning, judgment, and evaluating the accuracy of beliefs also become affected. This leads to delusions, where the usual mechanisms for testing whether beliefs match reality break down. A person becomes unable to recognize that their beliefs are false, even when presented with clear evidence contradicting them.^[4]

The disrupted thinking patterns characteristic of psychosis reflect problems with how the brain organizes and expresses thoughts. The connections between different ideas become loose or illogical, making it difficult to maintain a coherent train of thought or communicate clearly.^[7]

These neurological changes don’t just affect thoughts and perceptions—they impact the entire person. People experiencing psychosis often have heightened sensitivity to light, sound, or touch, while others may experience decreased sense of smell.^[18] The body’s stress response system becomes activated, leading to anxiety, fear, and physical manifestations of stress.

Sleep patterns frequently become disrupted, with some people sleeping during the day and remaining awake at night.^[18] Appetite changes, affecting eating patterns and potentially leading to weight changes. Energy levels and motivation often decrease, making it harder to care for oneself or complete daily tasks.^[18]

The cognitive impacts extend to memory, concentration, and the ability to learn new information. Many people describe feeling like their brain has stopped working or that they cannot think clearly.^[18] This can make it extremely difficult to function at work, in school, or in social situations.

The emotional toll of psychosis can be profound. Many people experience intense fear, confusion, and distress during episodes.^[3,7] Some describe feeling betrayed, unsafe even in their own homes, terrified, lonely, and frustrated.^[18] Others might alternate between confusion and excitement, or feel disconnected as if their feelings have disappeared.^[18]

The social consequences can be equally significant. As symptoms emerge, people often withdraw from relationships and activities they once enjoyed. Their ability to communicate effectively diminishes, making it harder to maintain connections with others. The dramatic changes in behaviour and thinking can be frightening or confusing to family members and friends, potentially leading to social isolation.^[18]

Physical health complications can also arise. People with psychosis have a higher than average risk of self-harm and suicide.^[3] Interestingly, research shows that people experiencing psychosis have a significantly higher chance of developing urinary tract infections, which are 29 times more common in patients with relapsed schizophrenia or those experiencing psychotic episodes.^[19]

Over time, without proper treatment, repeated psychotic episodes can affect long-term functioning. The ability to work, maintain relationships, live independently, and pursue personal goals may become increasingly compromised. However, with appropriate treatment and support, many people with psychotic disorders can manage their symptoms effectively and lead fulfilling lives.