TAC focuses on psychiatric conditions that include psychosis and other symptoms that are significant, persistent, and life-altering. TAC includes the most severe forms of the following conditions under the umbrella term of severe mental illness (SMI): schizophrenia spectrum disorders, bipolar disorder, and major depression with psychotic features. This definition of SMI is derived from the National Institute of Mental Health’s 1993 definition, which defines SMI “through diagnosis, disability and duration, and includes disorders with psychotic symptoms.”
of adults meet criteria for a schizophrenia spectrum disorder.
of adults meet criteria for Bipolar I or Bipolar II disorder.
of adults meet criteria for major depressive disorder with psychotic features.
of individuals with a schizophrenia spectrum disorder receive no treatment.
TAC’s definition of severe mental illness is based on diagnosis, disability, and duration.
Diagnosis: TAC focuses on disorders that can involve psychosis or psychotic features as defined by the Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.) (DSM-5 TR). These disorders are estimated to impact approximately 3.9% of the U.S. adult population.
- Schizophrenia spectrum disorders are disorders involving delusions, hallucinations, disorganized thinking, abnormal motor behavior, and negative symptoms. 1.2% of the U.S. adult population is estimated to meet criteria for a schizophrenia spectrum disorder within the past year.
- Bipolar disorders are disorders involving hypomanic, manic, and depressive mood episodes. Psychotic features can occur during manic episodes in bipolar I and major depressive episodes in both bipolar I and bipolar II, although they are somewhat less common in the depressive episodes of people with bipolar II. 1.5% of the U.S. adult population is estimated to meet criteria for bipolar I, while 0.8% of the U.S. adult population is estimated to meet criteria for bipolar II within the past year.
- Major depressive disorder is a condition defined by depressive mood episodes, that can include psychotic features. 0.4% of the population is estimated to meet criteria for major depressive disorder with psychotic features within the past year.
Disability: While we define SMI by these diagnoses, TAC’s advocacy and public education efforts focus on individuals with these conditions who experience the most severe, impairing, and life‑threatening symptoms. These are people who face persistent and unnecessary hardship due to both the severity of their illness and systemic failures to provide adequate, timely treatment.
This population is typically characterized by one or more of the following: recent or ongoing risk of serious harm to self or others, involvement with the criminal legal system, repeated difficulty engaging in community-based treatment resulting in deterioration or harm, eligibility for involuntary commitment, frequent interactions with crisis or emergency services, or an inability to maintain adequate nutrition, stable housing, employment, or relationships due to symptom severity.
To be characteristic of a severe mental illness, these outcomes must be directly attributable to symptoms of the illness, rather than primarily driven by external factors such as lack of access to healthcare, housing, transportation, or financial resources.
Duration: TAC believes in evidence-based standards for the diagnosis and treatment of severe mental illnesses, and accordingly considers a person to have SMI if they have been experiencing symptoms for a sufficient duration to meet diagnostic criteria outlined in the DSM-5 TR.
Click on the arrows below to learn some SMI terms & TAC definitions.
Psychosis is a state some individuals experience where they lose contact with external reality. Delusions, hallucinations, disorganized behavior, and incoherent speech are common symptoms. While experiencing psychosis, a person may feel very anxious or confused. They also may experience a loss of motivation and social withdrawal. Several disorders have psychosis as a symptom.
Schizophrenia spectrum disorders are a class of psychiatric disorders that are characterized by the presence of psychosis symptoms and a disconnection from reality. Schizophrenia is now considered to be on a spectrum, rather than having specific subtypes, which better classifies the continuum of symptoms a person may experience. Schizophrenia spectrum disorders include schizophrenia, schizoaffective disorder, and schizophreniform disorder.
Symptoms may include:
- Positive symptoms, such as delusions, hallucinations, disorganized speech, and behavior.
- Negative symptoms, such as struggling to take care of oneself, social withdrawal, flat affect, trouble with speech, and lack of pleasure.
- Cognitive symptoms, such as difficulty remembering things, organizing thoughts, and directing attention.
More than half of people with a SSD also have anosognosia, meaning that they lack insight into their illness.
Bipolar disorder is a mood disorder that consists of episodes of hypomanic, manic, and depressive mood episodes.
Bipolar I disorder consists of manic episodes that last for seven days or more, as well as depressive episodes that usually last two weeks or more. Mixed episodes are also possible, which means an individual experiences depressive and manic symptoms at the same time. Bipolar II disorder consists of hypomanic and depressive mood episodes.
Symptoms of mania may include:
- Changes in thought patterns (e.g. racing or disjointed thoughts, increased focus on religion, flights of ideas).
- Impaired judgement (e.g. extreme impulsiveness or risk taking, inappropriate humor, reckless spending).
- Mood changes (e.g. grandiosity, extreme excitability, sudden shifts to extreme irritability), speech disruptions (e.g. rapid and pressured speech, persistent rambling).
- Sudden changes in energy (e.g. sleeping very little, restlessness, persistent movement, sudden increase in goal-oriented activities).
Some individuals may experience psychosis while experiencing a manic or depressive episode.
Anosognosia, or lack of insight, refers to a symptom of severe mental illness that impairs a person’s ability to understand or perceive their own illness. Anosognosia is thought to be the most common reason for not seeking or maintaining treatment for people with SMI.
Some studies of anosognosia suggest that this is a result of anatomical damage in the part of the brain that is involved in self-reflection. This condition can also be seen in some individuals with Alzheimer’s disease, after a stroke, and other neurological conditions.
SMI Resources
If you or a loved one has been diagnosed with a severe mental illness and want to learn more, please visit the Schizophrenia and Psychosis Resource Center page for psychoeducation and support.