Drugs
Encephalitis
Metabolic (eg, electrolyte or liver abnormality, dehydration, acute intermittent porphyria)
Endocrine (thyroid disease, diabetes mellitus)
Normal-pressure hydrocephalus
Trauma (eg, chronic subdural hematoma)
Infection (eg, of lung or urine, AIDS, syphilis)
Affective disorder (ie, depression manifesting as pseudodementia)
Structural defect of brain (eg, infarction, tumour, abscess)