Dementia is defined as a brain disorder that includes memory
loss, deficits in cognition (thinking, planning, and organizing
abilities), a decline in emotional control or motivation, and
changes in social behavior (such as increased irritability,
apathy, or problems interacting with other people).
Alzheimer's disease (also referred to as dementia of the
Alzheimer's type), which affects roughly five million Americans
and more than 35 million people around the world, is by far the
most common dementia. About 50% to 56% of people with dementia
are diagnosed with Alzheimer's, while another 13% to 17% carry
that diagnosis plus a related disorder, vascular dementia. Here
is a brief review of the most common dementia syndromes in the
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