Differences Between Bipolar Disorder and Schizophrenia

Psychosis, which includes hallucinations and delusions, is a hallmark symptom of schizophrenia. People with bipolar I disorder can have psychotic symptoms during mania and/or depression, and those with bipolar II can have them during an episode of depression. So while bipolar disorder and schizophrenia can share a set of serious symptoms, when distinguishing between the two disorders, doctors look at the differences between symptoms and also give different weight to some of the shared symptoms.

Symptoms of Schizophrenia

These are the main symptoms of schizophrenia in adults:

 1. For most of a month, a patient must have two of these symptoms:

• Delusions
• Hallucinations
• Disorganized speech — Derailment or incoherence (also known as word salad) where there is no connection between spoken words at all. For example, "Coffee abstract welcome tiptoes glue kitchen puppy."

If only one of these symptoms is present, one of the following must also appear:

• Extreme and abnormal psychomotor behavior, which includes catatonia
• Negative symptoms
• Alogia — A reduction in the amount of speech or quality of speech
• Flattened affect — Having little or no emotion
• Anhedonia — Loss of pleasure
• Avolition — Severe lack of initiative

2. At the same time, there's a marked decrease in at least one important area of functioning, such as:

• Work
• School
• Relations with others
• Self-care, such as cleanliness

In addition to the month of acute symptoms, the overall disturbance must have persisted for at least six months.

Symptoms of Bipolar Disorder

None of the symptoms of delusions, hallucinations, and disorganized speech and behavior have to be present for someone to be diagnosed with bipolar disorder, although they may be present. In fact, the only requirement for a diagnosis of bipolar I disorder is that the patient has had one manic episode; though depression is also common, it isn't required for a diagnosis. And for bipolar II, the requirements are almost as simple: no manic episodes, at least one hypomanic episode, and at least one major depressive episode.

In bipolar disorder, another requirement is that the symptoms cause significant problems with occupational and/or social functioning. This is similar to number two under schizophrenia, but the reasons for the impairment are, in general, profoundly different.

Diagnostic Differences

Here's a summary of the differences between the diagnostic requirements for the two illnesses: