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Mental illness affects 26.2% of the population of the world's adult population in any given year.


Dementia is a disorder consisting of a pervasive disturbance in cognition that impairs memory, abstraction, judgment, personality, and higher critical functions such as language. Its onset is typically gradual, and the patient's normal level of consciousness is maintained. The presence of global cognitive impairment can be detected by using a bedside screening test such as the Mini-Mental State Exam or the Clock Drawing Test. Potentially reversible causes of dementia should be sought including metabolic and endocrine disorders, adverse drug effects and interactions, and depression.


Delirium is characterized by acute development of impairment in cognitive function, diminished level of consciousness, inattention, and sensory misperceptions that fluctuate over the course of hours. Visual hallucinations are common. Delirium is frequently missed in the ED and is associated with a high mortality rate. The causes of delirium should be sought and treated. Causes include infection, electrolyte abnormalities, toxic and medication ingestion, and head injury

Amnestic Disorders

Amnestic patients cannot learn new information or recall previously learned information. Amnesia may be due to brain trauma, stroke, anoxic brain injury, substance abuse, and chronic nutritional deficiencies.

Substance-Use Disorders

Intoxication is an exogenous substance-induced syndrome that results in maladaptive behavior and impaired cognitive functioning and psychomotor activity. Judgment, perception, attention, and emotional control may be affected. Substance withdrawal symptoms may develop when the amount ingested is reduced or stopped. The symptoms and timing of withdrawal depend on the substance of abuse.

Schizophrenia and Other Psychotic Disorders

Schizophrenia is a chronic disease characterized by positive symptoms such as hallucinations, delusions, disorganized speech or behavior, or catatonic behavior and negative symptoms such as blunted affect, emotional withdrawal, lack of spontaneity, anhedonia, or impaired attention. Chronic illness is distinguished by cognitive impairment with loose associations or incoherence and the relative absence of a mood disorder. Patients may present to the emergency department for worsening psychosis, suicidal ideations, crisis, bizarre or violent behavior, or adverse medication events. Typical antipsychotic medications, such as haloperidol, effectively treat the positive symptoms, and newer atypical antipsychotic medications, such as aripiprazole, quetiapine, olanzapine, risperidone, ziprasidone, and clozapine, effectively treat positive and negative symptoms. The diagnosis of schizophreniform disorder is made when an individual experiences symptoms and demonstrates signs consistent with schizophrenia for less than 6 months. A brief psychotic disorder is a psychosis that lasts less than 4 weeks in response to a traumatic life experience, such as sexual assault, natural disaster, combat, or death of a loved one. Schizophrenia is treated with antipsychotic medications.

Mood Disorders

Major Depression

Major depression is characterized by a persistent ...

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