Dementia is diagnosed by looking at the person’s symptoms, medical history, and how the problems affect daily life. A doctor may do memory and thinking tests, ask about behaviour changes, and check for other possible causes. Blood tests or brain scans may also be used in some cases. The goal is to find out whether the symptoms are due to dementia or another condition that can be treated. Diagnosis is usually a process rather than one single test. Family observations are often helpful too.