To determine a diagnosis and check for related complications, you may have:
- A physical exam. Your doctor will try to rule out physical problems that could cause your symptoms.
- Lab tests. These may include, for example, a check of your thyroid function or a screening for alcohol and drugs.
- A psychological evaluation. A doctor or mental health provider talks to you about your symptoms, thoughts, feelings and behavior patterns. You may be asked to fill out a questionnaire to help answer these questions.
Classes of mental illness
The main classes of mental illness are:
- Neurodevelopmental disorders. This class covers a wide range of problems that usually begin in infancy or childhood, often before the child begins grade school. Examples include autism spectrum disorder, attention-deficit/hyperactivity disorder (ADHD) and learning disorders.
- Schizophrenia spectrum and other psychotic disorders. Psychotic disorders cause detachment from reality — such as delusions, hallucinations, and disorganized thinking and speech. The most notable example is schizophrenia, although other classes of disorders can be associated with detachment from reality at times.
- Bipolar and related disorders. This class includes disorders with alternating episodes of mania — periods of excessive activity, energy and excitement — and depression.
- Depressive disorders. These include disorders that affect how you feel emotionally, such as the level of sadness and happiness, and they can disrupt your ability to function. Examples include major depressive disorder and premenstrual dysphoric disorder.
- Anxiety disorders. Anxiety is an emotion characterized by the anticipation of future danger or misfortune, along with excessive worrying. It can include behavior aimed at avoiding situations that cause anxiety. This class includes generalized anxiety disorder, panic disorder and phobias.
- Obsessive-compulsive and related disorders. These disorders involve preoccupations or obsessions and repetitive thoughts and actions. Examples include obsessive-compulsive disorder, hoarding disorder and hair-pulling disorder (trichotillomania).
- Trauma- and stressor-related disorders. These are adjustment disorders in which a person has trouble coping during or after a stressful life event. Examples include post-traumatic stress disorder (PTSD) and acute stress disorder.
- Dissociative disorders. These are disorders in which your sense of self is disrupted, such as with dissociative identity disorder and dissociative amnesia.
- Somatic symptom and related disorders. A person with one of these disorders may have physical symptoms with no clear medical cause, but the disorders are associated with significant distress and impairment. The disorders include somatic symptom disorder (previously known as hypochondriasis) and factitious disorder.
- Feeding and eating disorders. These disorders include disturbances related to eating, such as anorexia nervosa and binge-eating disorder.
- Elimination disorders. These disorders relate to the inappropriate elimination of urine or stool by accident or on purpose. Bedwetting (enuresis) is an example.
- Sleep-wake disorders. These are disorders of sleep severe enough to require clinical attention, such as insomnia, sleep apnea and restless legs syndrome.
- Sexual dysfunctions. These include disorders of sexual response, such as premature ejaculation and female orgasmic disorder.
- Gender dysphoria. This refers to the distress that accompanies a person’s stated desire to be another gender.
- Disruptive, impulse-control and conduct disorders. These disorders include problems with emotional and behavioral self-control, such as kleptomania or intermittent explosive disorder.
- Substance-related and addictive disorders. These include problems associated with the excessive use of alcohol, caffeine, tobacco and drugs. This class also includes gambling disorder.
- Neurocognitive disorders. Neurocognitive disorders affect your ability to think and reason. These acquired (rather than developmental) cognitive problems include delirium, as well as neurocognitive disorders due to conditions or diseases such as traumatic brain injury or Alzheimer’s disease.
- Personality disorders. A personality disorder involves a lasting pattern of emotional instability and unhealthy behavior that causes problems in your life and relationships. Examples include borderline, antisocial and narcissistic personality disorders.
- Paraphilic disorders. These disorders include sexual interest that causes personal distress or impairment or causes potential or actual harm to another person. Examples are sexual sadism disorder, voyeuristic disorder and pedophilic disorder.
- Epilepsy is a central nervous system (neurological) disorder in which brain activity becomes abnormal, causing seizures or periods of unusual behavior, sensations, and sometimes loss of awareness. Seizure symptoms can vary widely. Some people with epilepsy simply stare blankly for a few seconds during a seizure, while others repeatedly twitch their arms or legs. Having a single seizure doesn’t mean you have epilepsy. At least two unprovoked seizures are generally required for an epilepsy diagnosis.
- Other mental disorders. This class includes mental disorders that are due to other medical conditions or that don’t meet the full criteria for one of the above disorders.