Dementia is a loss of mental skills that affects daily life and usually gets worse over time. It can be caused by neurodegenerative conditions like Alzheimer's disease, vascular diseases, head injuries, strokes, infections, and certain genetic disorders. Dementia is diagnosed through medical history, exams, and lab tests and stages progress from mild cognitive impairment to moderate and severe dementia. Treatment involves medications to address symptoms, care to support daily living, and management of behaviors.