Intoxication | Alcohol, sedatives, bromides, analgesics (eg, pentazocine), psychedelic drugs, stimulants, and household solvents. |
Medication withdrawal | Withdrawal from alcohol, sedative-hypnotics, corticosteroids. |
Long-term effects of alcohol | Wernicke-Korsakoff syndrome. |
Infections | Septicemia; meningitis and encephalitis due to bacterial, viral, fungal, parasitic, or tuberculous organisms or to central nervous system syphilis; acute and chronic infections due to the entire range of microbiologic pathogens. |
Endocrine disorders | Thyrotoxicosis, hypothyroidism, adrenocortical dysfunction (including Addison disease and Cushing syndrome), pheochromocytoma, insulinoma, hypoglycemia, hyperparathyroidism, hypoparathyroidism, panhypopituitarism, diabetic ketoacidosis. |
Respiratory disorders | Hypoxia, hypercapnia. |
Metabolic disturbances | Fluid and electrolyte disturbances (especially hyponatremia, hypomagnesemia, and hypercalcemia), acid-base disorders, hepatic disease (hepatic encephalopathy), kidney failure, porphyria. |
Nutritional deficiencies | Deficiency of vitamin B1 (beriberi), vitamin B12 (pernicious anemia), folic acid, nicotinic acid (pellagra); protein-calorie malnutrition. |
Trauma | Subdural hematoma, subarachnoid hemorrhage, intracerebral bleeding, concussion syndrome. |
Cardiovascular disorders | Myocardial infarctions, cardiac arrhythmias, cerebrovascular spasms, hypertensive encephalopathy, hemorrhages, embolisms, and occlusions indirectly cause decreased cognitive function. |
Neoplasms | Primary or metastatic lesions of the central nervous system, cancer-induced hypercalcemia. |
Seizure disorders | Ictal, interictal, and postictal dysfunction. |
Collagen-vascular and immunologic disorders | Autoimmune disorders, including systemic lupus erythematosus, Sjögren syndrome, and AIDS. |
Degenerative diseases | Alzheimer disease, Pick disease, multiple sclerosis, parkinsonism, Huntington chorea, normal pressure hydrocephalus. |
Medications | Anticholinergic medications, antidepressants, H2-blocking agents, digoxin, salicylates (long-term use), and a wide variety of other over-the-counter and prescribed medications. |