Paranoia is a state of mind in which a person believes that others are trying to harm, deceive or exploit them. It could be a feeling of being watched, listened to, followed or monitored in some way. It might be a belief that there is some kind of conspiracy operating against them. People with paranoia sometimes have an increased sense of self-importance, believing that many others are taking notice of them when it is not true.

Mild paranoid thoughts are quite common in the general population and tend to recover naturally. Long-term paranoia can be a symptom of a mental health disorder or be caused by recreational drug abuse, dementia or other medical conditions that affect the brain. Paranoia doesn't necessarily come from a mental illness.

Paranoia is sometimes referred to as a persecutory delusion. A delusion is a fixed, false belief that someone continues to hold even when there is no evidence that the belief is true.

People become paranoid when their ability to reason and assign meaning to things breaks down. The reason for this is unknown. It’s thought paranoia could be caused by genes, chemicals in the brain or by a stressful or traumatic life event. It’s likely a combination of factors is responsible.

Research has shown that mild paranoid thoughts are fairly common in the general population.

However, paranoia can be caused by a mental health disorder including:

Paranoid personality disorder

A personality disorder is a long-standing pattern of problematic thoughts, feelings and behaviour. People with paranoid personality disorder have a tendency to assume that others will harm, deceive or take advantage of them. They may appear secretive, argumentative or cold and be difficult to get along with. This disorder is uncommon and usually improves with age so that many people recover by their 40s or 50s.

Delusional disorder

People with a delusional disorder have one delusion (a fixed, false belief) without any other symptoms of mental illness. Paranoid delusions are the most common, making people feel there is a conspiracy or they are going to be harmed. But people with a delusional disorder can also have other types of unusual beliefs.

If someone you know has paranoia, it’s important not to tell them they are imagining things or that they are crazy. Their paranoid thoughts are very real to them. Understanding and support are the best way of encouraging them to seek help from a professional.

Paranoid schizophrenia

Schizophrenia is a form of psychosis and causes people to have trouble interpreting reality. The main symptoms are hallucinations (such as hearing voices that aren’t there) and delusions. Some people with schizophrenia have bizarre delusions such as believing that their thoughts are being broadcast over the radio or they are being persecuted by the government. Other symptoms include confused thinking and reduced motivation for everyday tasks.

Mood disorders

Psychotic disorder and bipolar disorder can cause paranoia.

Other causes of paranoia include:

• Recreational drug use: Cannabis and amphetamine abuse often causes paranoid thoughts and may trigger an episode of psychosis. Other drugs such as alcohol, cocaine and ecstasy can also cause paranoia during intoxication or withdrawals.
• Neurological disease: Diseases such as dementia (including Alzheimer’s disease), Huntington’s disease, Parkinson’s disease or brain injury can cause paranoia.
• Severe trauma and stress: Some studies have found that paranoia is more common in people who have experienced severe and ongoing stress. This may include abuse in childhood, domestic violence, racial persecution or living in isolation.

Paranoid symptoms can range from a general feeling of distrust and suspicion of others through to bizarre and complicated beliefs such as conspiracy theories about the government, police or aliens.

Being paranoid could mean someone:

• distrusts or is suspicious of others
• develops conspiracy theories
• feels very self-important, that people should take notice of them
• feels angry, betrayed or afraid
• is hypervigilant
• finds it hard to forgive others
• becomes defensive when beliefs are questioned or they are criticised
• is preoccupied with others’ hidden motives
• is afraid of being taken advantage of
• can’t relax
• is argumentative

People with paranoia can become very anxious about their specific fear. But paranoia is not the same as anxiety. Anxiety is when someone worries excessively about dangers to themselves and others. Paranoia is when someone has delusional and irrational thinking or behaviour.

Because paranoia can be the sign of a mental health condition or brain injury, it is important to see a doctor if you or someone you know is experiencing paranoia.

If you or someone you know often has paranoid thoughts and feelings and they are causing distress, then it’s important to seek professional help.

If you are worried about someone else’s paranoia, it’s best not to criticise them or tell them they are imagining things. Their thoughts are real to them and they need support.

A mental health assessment by a doctor or mental health professional can help determine the cause of the paranoia. An assessment involves detailed questions about the current problems, past and family history of mental health issues, general medical history and any medicines or drug and alcohol use.

A doctor may need to do a physical examination, blood tests or scans to rule out an underlying physical cause. They may need to refer to a psychiatrist if a diagnosis of mental illness or personality disorder is suspected. Finding out the cause or diagnosis is the first step towards effective treatment.

The cause of paranoia can be difficult to diagnose. People with paranoia may not be able to recognise that they have a problem, and may avoid doctors or hospitals due to a fear of being harmed.

Treatment for paranoia depends on the underlying cause. It may include psychological therapy or medicine. Stopping the use of alcohol or recreational drugs can be the first step and may solve the problem altogether.

People with paranoid thoughts can find it hard to trust a doctor or mental health professional, and may have difficulty accepting treatment. Developing a positive relationship with a health provider may take time, but can lead to recovery.

Psychotherapy (including cognitive behaviour therapy) can be helpful for mild cases of paranoia or paranoid personality disorder. This can help a person to develop insight into the condition, cope with symptoms and develop a more realistic view of the motives of others.

For conditions such as psychosis, schizophrenia or delusional disorders, the main treatment is medicine. These conditions are now more treatable than ever before, and many new antipsychotic medicines are available. These conditions usually require treatment by a psychiatrist. Psychotherapy, rehabilitation or support groups may also be effective in conjunction with medicine.