Causes

Dementia may be reversible or irreversible. Reversible causes include brain
tumors, subdural hematoma, slowly progressive or normal-pressure hydrocephalus;
head trauma; endocrine conditions (such as hypothyroidism,
hypercalcemia, hypoglycemia); vitamin deficiencies (of thiamin, niacin, or
vitamin B12); thyroid disease; ethanol abuse; infections; metabolic abnormalities;
effects of medications; renal, hepatic, and neurological conditions;
and depression. Irreversible dementia is more common in the elderly. Irreversible
causes of dementia include diseases of the brain such as Alzheimer’s,
Parkinson’s, Pick’s, Creutzfeldt-Jakob, and Huntington’s diseases;
human immunodeficiency virus (HIV) infection; vascular dementia; and
head trauma.