| Drugs and poisons |
| Alcohol, beta blockers, steroids, opiates, barbiturates, withdrawal from cocaine and amphetamines, heavy metal poisoning, cholinesterase inhibitors, cimetidine, chemotherapy agents |
| Metabolic/endocrine |
| Hyper- and hypothyroidism, severe anemia, hyperparathyroidism, hypokalemia, hyponatremia, Cushing disease, Addison disease, uremia, hypopituitarism, porphyria, Wilson Disease, Wernicke-Korsakoff syndrome |
| Infectious diseases |
| Tuberculosis, Epstein-Barr infection, HIV, pneumonia, postinfluenza, tertiary syphilis, encephalitis, and postencephalitic states |
| Neurodegenerative and demyelinating diseases |
| Alzheimer disease, multiple sclerosis, Parkinson disease, Huntington disease |
| Other neurologic |
| Subdural hematoma, normal pressure hydrocephalus, strokes, posttraumatic brain injury syndromes, cerebral tumors |
| Neoplasia |
| Carcinomatosis, cancers of the pancreas, lung, breast, and others |
| Others |
| Systemic lupus erythematosus, other collagen vascular disorders, other chronic inflammatory or autoimmune disorders, heart failure |
