Dementia is defined as a syndrome and generally means gradual decrease in the ability to think and remember that is great enough to affect a person’s daily functioning. The most common type of dementia is Alzheimer’s disease which makes up 50% to 70% of cases. Other common types include vascular dementia (25%), Lewy body dementia (15%), and frontotemporal dementia. Alzheimer dementia has been discussed in the present review.