Schizophrenia involves periods of psychosis, with symptoms like delusions and hallucinations. Schizoid personality disorder is a persistent pattern of thoughts and behaviors that cause distress but don’t involve distorted perceptions.
Schizophrenia and schizoid personality disorder don’t have a causal relationship, nor do they involve the exact same emotional and behavioral experiences.
Schizophrenia is listed under “Schizophrenia spectrum and other psychotic disorders” in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR), the go-to reference handbook for most U.S. mental health professionals. Schizoid personality disorder, on the other hand, appears under “Personality disorders.”
This means these disorders have separate diagnostic criteria and management approaches.
Psychotic disorders refer to mental health conditions that involve a distorted perception that makes it difficult for a person to determine what’s real and what’s not real in the external world.
Personality disorders involve personality traits and persistent thoughts, emotions, and behaviors that cause long-standing distress and affect the way you see yourself and the world around you.
Schizoid personality disorder is one of 10 formal personality disorders and falls into cluster A, a group of conditions the DSM-5-TR says are characterized by eccentric, odd, or detached thoughts and behaviors. Paranoid and schizotypal personality disorders are also part of cluster A.
These are the formal symptoms of both conditions:
| Schizophrenia | Schizoid personality disorder |
|---|---|
| Delusions (false beliefs that don’t change despite evidence) | Avoidance of close and meaningful relationships and intimacy, including with relatives (no desire to connect emotionally with others) |
| Hallucinations (distorted perceptions like seeing or hearing something others cannot) | Preference for solitary activities, time alone, and abstract tasks |
| Disorganized speech (switching from topic to topic or using inadequate words in random order) | Low or no interest in sexual experiences with yourself or others |
| Disorganized behavior (including agitation or catatonia) | Difficulty finding joy in regular activities (preferring to be a witness than a participant in most activities) |
| Inability to experience pleasure | Indifference to what others think or say about you or something else |
| Flat affect or inability to express emotions | Flat affect and detachment |
| Disorganized thinking | Lack of close friends or meaningful relationships |
| Severe lack of motivation | |
| Social withdrawal |
To reach a diagnosis of schizophrenia, a mental health professional will try to establish that two or more schizophrenia symptoms have been persistent for at least 1 month or longer. The diagnosis requires that at least one of those symptoms be hallucinations, delusions, or disorganized speech.
For schizoid personality disorder, the mental health professional will need to establish a long-standing pattern of four or more of the symptoms listed above. These should be present over time and across most situations and cause a degree of distress.
Healthcare professionals will also want to explore if these symptoms are a result of other conditions, including schizophrenia, bipolar disorder, or autism spectrum disorder, in which case they would not diagnose the personality disorder.
Medical professionals haven’t established the causes of schizophrenia and schizoid personality disorder yet. Experts believe a combination of genetic, environmental, and experiential factors may be at play in both conditions.
For schizophrenia, factors may
- chemical and structural changes in the brain
- having one or more close relatives who’ve received a diagnosis of schizophrenia or other psychotic disorders
- environmental stressors, including long-term poverty, nutritional deficiencies, or living in fear
More research involving humans is needed to determine the role these and other factors play in the development of schizophrenia.
The causes of schizoid personality disorder aren’t clear, either. Possible risk factors
- adverse childhood experiences, including neglect and abuse
- first-degree relatives who’ve received a diagnosis of schizophrenia, schizoid personality disorder, or schizotypal personality disorder
- low levels of platelet monoamine oxidase (MAO) enzymes in the brain, which help balance neurotransmitters and are associated with sociability
Health professionals don’t consider schizophrenia or schizoid personality disorder to be “curable” conditions. This means they likely require ongoing treatment for life to manage symptoms and decrease distress.
The main difference in the treatment of these conditions is that schizoid personality disorder rarely requires medications to manage symptoms, while schizophrenia does.
Schizoid personality disorder responds well to psychotherapy, but it may be difficult for someone with the condition to realize they need support. If they do, therapy can help with interpersonal friction, occupational challenges, and distress reduction.
The first line of treatment for schizophrenia is antipsychotic medications to reduce the frequency and intensity of symptoms like hallucinations and delusions.
Psychotherapy focusing on behavioral training, like cognitive behavioral therapy, can also help reduce distress and interpersonal conflict. It may also help someone manage everyday challenges with work, school, or personal care.
Read more on antipsychotic medications for schizophrenia.
If you meet the diagnostic criteria for schizophrenia, you’ll likely receive that diagnosis even if you have symptoms of a personality disorder.
Some people with schizoid personality disorder
Schizophrenia and schizoid personality disorder are two different mental health conditions. While schizophrenia involves symptoms of psychosis, like hallucinations or delusions, the personality disorder rarely, if ever, does. Both conditions may involve a degree of social withdrawal and flat affect, though.
Management is also different for schizophrenia, which often requires ongoing pharmaceutical treatment with antipsychotic medications in addition to behavioral therapy. Schizoid personality disorder doesn’t respond to medications, but some symptoms may decrease with long-term psychotherapy.
Having either condition may require ongoing management, but relief is possible, and support is available and effective.