Alzheimer’s Disease is a neurodegenerative disease characterized in its early stages by the difficulty in acquiring new memories, diminished language capacity, depression, irritability, apathy, aggression, inability to concentrate, long term memory loss, and/or loss of motor control (no, we don’t all have it even when it feels like it sometimes :). This combination of symptoms combined with an examination of a patient’s brain post mortem, confirms a diagnosis of Alzheimer’s Disease. Dementia can include all of these symptoms and more, but can have a number of different causes such as stroke, physical injury or substance abuse. Dementia is not a specific diagnosis, but a description of a collection of symptoms that has or has not necessarily been attributed to a specific cause, like injury, etc. The word dementia, although referring to a completely different host of symptoms, is used similarly to the word colic in that they both describe manifestations of a symptoms, but are not a specific diagnosis (colic describes extended periods of crying and irritability in infants between 2 weeks and 3 months old).
In summary, Alzheimer’s Disease is a specific diagnosis, named after a the guy who discovered it – Alois Alzheimer in 1906, whereas dementia describes a collection of symptoms that have a number of possible causes. Alzheimer’s Disease is confirmed by cognitive – behavioural assessments and brain scans, and is confirmed post mortem by an autopsy.