By consensual agreement within the American Psychiatric Association psychiatric diagnoses are descriptive labels only for phenomenology, not etiological or mechanistic explanation for syndromes. Thus, a psychiatric diagnosis labels a pattern of signs and symptoms, but offers no hypothesis concerning the mechanism(s) of the clinical phenomena.(Davidoff et al.,1991).
The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) classifies psychotic illnesses as “Psychosis Due to General Medical Conditions”, and “Substance Induced Psychosis”. (DSM-IV Codes 293.81 & 292.11). Distinguishing medical conditions and substance-induced psychosis from schizophrenia or Bipolar disorder through clinical presentation often is difficult.
Psychosis Due to a Medical Condition involve a surprisingly large number of different medical conditions, some of which include: brain tumors, cerebrovascular disease, Huntington’s disease, multiple sclerosis, Creitzfeld-Jakob disease, anti-NMDAR Encephalitis, herpes zoster-associated encephalitis, head trauma, infections such as neurosyphilis, epilepsy, auditory or visual nerve injury or impairment, deafness, migraine, endocrine disturbances, metabolic disturbances, vitamin B12 deficiency, a decrease in blood gases such as oxygen or carbon dioxide or imbalances in blood sugar levels, and autoimmune disorders with central nervous system involvement such as systemic lupus erythematosus have also been known to cause psychosis.
A substance-induced psychotic disorder, by definition, is directly caused by the effects of drugs including alcohol, medications, and toxins. Psychotic symptoms can result from intoxication on alcohol, amphetamines (and related substances), cannabis (marijuana), cocaine, hallucinogens, inhalants, opioids, phencyclidine (PCP) and related substances, sedatives, hypnotics, anxiolytics, and other or unknown substances. Psychotic symptoms can also result from withdrawal from alcohol, sedatives, hypnotics, anxiolytics, and other or unknown substances.
Some medications that may induce psychotic symptoms include anesthetics and analgesics, anticholinergic agents, anticonvulsants, antihistamines, antihypertensive and cardiovascular medications, antimicrobial medications, antiparkinsonian medications, chemotherapeutic agents, corticosteroids, gastrointestinal medications, muscle relaxants, nonsteroidal anti-inflammatory medications, other over-the-counter medications, antidepressant medications, neurleptic medications, antipsychotics, and disulfiram . Toxins that may induce psychotic symptoms include anticholinesterase, organophosphate insecticides, nerve gases, heavy metals, carbon monoxide, carbon dioxide, and volatile substances (such as fuel or paint).
Before assigning the diagnosis of Bipolar Disorder or Schizophrenia due diligence should be asserted in the clinical evaluation of psychotic and manic symptoms to address “Psychosis Due to General Medical Conditions”, and “Substance Induced Psychosis” (DSM-IV Codes 293.81 & 292.11). Improvements in the diagnostic accuracy and treatment of psychosis is cost-effective for both the mental health consumer and society. Advocacy for mental illness must include the consideration of underlying etiological factors of psychiatric symptoms.