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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. Potentially reversible causes of dementia include 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. The causes of delirium are frequently treatable and include infection, electrolyte abnormalities, toxic ingestions, and head injury. Treatment is directed toward correcting the underlying cause.

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-Induced 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. Repeated use (substance abuse) may lead to physical or psychological dependence. Substance withdrawal symptoms may develop when the amount ingested is reduced or stopped. Symptoms and timing of withdrawal depend on the substance of abuse.

Schizophrenia and Other Psychotic Disorders

Schizophrenia is a chronic disease characterized by functional deterioration. Clinical features include “positive symptoms” such as hallucinations, delusions, disorganized speech or behavior, or catatonic behavior, “negative symptoms” such as blunted affect, emotional withdrawal, lack of spontaneity, anhedonia, or impaired attention, as well as 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, bizarre or violent behavior, or adverse medication events. Older antipsychotic medications, such as haloperidol, effectively treat the “positive symptoms,” and newer 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.

Mood Disorders

Major Depression

Major depression is characterized by a persistent dysphoric mood or a pervasive loss of interest and pleasure in usual activities (anhedonia) that lasts longer than 2 weeks. Associated psychological symptoms include feelings of guilt over past events, self-reproach, worthlessness, hopelessness, and recurrent thoughts of death or suicide. ...

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