Schizophrenia vs. dissociative identity disorder: How do they differ?

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Schizophrenia is a psychotic disorder. It can cause behavior changes and symptoms such as hallucinations — instances in which a person sees, hears, or feels things that are not really there. It can also cause people to experience delusions, meaning they believe things that are not true. Schizophrenia affects how a person thinks, feels, and experiences reality.

DID — which experts referred to as multiple personality disorder or split personality disorder until 1994 — is a dissociative disorder in which a person has multiple identities that function independently. They are separate personality states with different memories and behaviors, and they may even have different voices, language, or perceived appearance.

The two disorders have symptoms and causes that may overlap, including a disconnection from reality. However, while people with schizophrenia have false ideas and delusions, they do not experience different personality states.

Read more about schizophrenia and DID.

Dissociative vs. psychotic disorders

The Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR) categorizes schizophrenia as a psychotic disorder, whereas DID is a dissociative disorder.

The definition of dissociation in the DSM-5-TR includes a disruption in the standard flow of:

• consciousness
• memory
• identity
• emotion
• perception
• motor control
• behavior

Psychosis is a loss of touch with reality. It may cause hallucinations and delusions.

The difference between the two is that dissociation tends to cause a disconnection from reality, such as the sense of who a person is, while psychosis tends to add something to reality, such as hallucinations.

Why do people confuse them?

Many people confuse the two disorders because they have overlapping criteria. Studies suggest that 9–50% of people with schizophrenia also meet the criteria for DID. Hearing voices in one’s head may seem or feel similar to having multiple identities in one’s head.

The two conditions share the following symptoms:

• hallucinations, which can be visual or auditory
• suicidal ideation
• delusions
• dissociation

Sometimes doctors or mental health professionals may mistakenly assume that a person who believes they have multiple personalities is experiencing delusions. Delusions differ from having multiple identities, as they can be ideas or beliefs that have no grounds in reality.

Symptoms that may occur in both DID and schizophrenia include:

• amnesia, or memory loss
• hearing voices
• a sense of disconnection from other people

However, the two disorders also have differing symptoms, as the table below illustrates.

Studies have found that hallucinations, such as hearing voices, occur less often in DID than in schizophrenia.

The causes of DID and schizophrenia differ. Experts do not know the exact cause of schizophrenia, but it may be a combination of genetic, environmental, and psychological factors.

DID and other dissociative disorders are usually the result of trauma. Dissociation is how the mind can cope with traumatic experiences or extreme stress. According to the American Psychiatric Association, 90% of people with DID in the United States, Canada, and Europe have experienced severe neglect and childhood abuse.

Other traumatic experiences that may result in DID include:

• war or military combat
• physical abuse
• sexual abuse
• emotional abuse

Switching off from reality is a standard way of responding to something that the body or mind feels it cannot cope with. The United Kingdom’s National Health Service (NHS) describes this as a sense of denial, as if the event or situation is not happening to the person.

It becomes an issue when this sense of switching off remains even when a person’s environment is no longer threatening.

Treatments for the two disorders differ. For example, doctors may prescribe antipsychotic medication to manage hallucinations in schizophrenia, but they do not treat DID with antipsychotics.

Treatment for both disorders involves psychotherapy, which can include:

• talking therapies such as cognitive behavioral therapy (CBT), which can help manage hallucinations, symptoms such as anxiety, and episodes of dissociation
• support from mental health professionals
• medications for accompanying symptoms such as anxiety and depression

With treatment, people with DID and schizophrenia can live healthy, fulfilling lives.

Both schizophrenia and DID are rare disorders. Schizophrenia affects just 1% of adults worldwide. The World Health Organization (WHO) estimates that it affects 1 in 300 people globally. Males are more likely to receive this diagnosis than females.

DID affects 1.5% of people globally, and females are more likely to receive this diagnosis. According to the National Alliance on Mental Illness, up to 75% of people may experience depersonalization or derealization at least once in their lifetime. This can feel like a person is outside their body or that the world does not seem real. It can result from stressful or traumatic situations.

Both schizophrenia and DID have connections to suicide and other mental health conditions, such as anxiety and depression.

The NHS states that those with schizophrenia have an increased risk of suicide. This may be a result of trying to manage symptoms such as hallucinations and delusions and live a fulfilled life.

If the family or friends of a person with schizophrenia notice that the person experiences low periods or mentions suicidal thoughts, it is important to report these to a healthcare professional.

People with DID may also experience suicidal thoughts and a tendency toward self-harm. Suicidal thoughts may occur during dissociation, when a person has a decreased pain intolerance.

DID and schizophrenia have some overlapping symptoms, but they are separate conditions. While people with either condition may experience delusions, depression, and suicidal thoughts, people with DID experience multiple identities or personalities, while those with schizophrenia do not.

The causes of both disorders may stem from trauma, but experts do not know the exact cause of schizophrenia. Treatment for both conditions includes talk therapy such as CBT.