Diagnosis

There is no single reliable biological test to diagnose AD; therefore, criteria
to assist primary care providers in diagnosing AD have been established to
differentiate between AD and other forms of dementia. One such guideline
has been established by the Agency for Health Care Policy and Research
(AHCPR). Any positive response to six identified areas warrants a workup
for dementia. New diagnostic tools and criteria make it possible for health
care providers to make a positive clinical diagnosis of AD with around 90
percent accuracy.
Diagnostic criteria for AD includes dementia, history, physical and mental
examinations consistent with AD, normal blood tests, and medications
that are not the cause of dementia. Brain imaging study—computed tomography
(CT) or magnetic resonance imaging (MRI)—is normal or shows
brain atrophy.
A medical history provides information about mental or physical conditions,
prescription drugs, and family health history. A physical examination
evaluates nutritional status, blood pressure, and pulse. A neurological examination
evaluates for neurological disorders. The Mini-Mental State Examination
(MMSE) and Addenbrooke’s Cognitive Examination (ACE) are instruments
used to evaluate AD.
Blood and urine tests evaluate for other causes of dementia. Psychiatric
evaluation assesses mood and emotional factors that mimic dementia. A
neuropsychological assessment evaluates memory, sense of time and place,
and ability to understand, communicate, and do simple calculations.
MRI and CT scans of the brain assess for the possibility of other potential
causes of dementia, such as stroke, Huntington’s disease, or Parkinson’s disease.
Early diagnosis of AD is important to determine the proper treatment and
to detect underlying diseases such as depression, drug interactions, vitamin
deficiencies, or endocrine problems. These diseases may be reversible if detected
early. A definitive diagnosis of AD can only be confirmed on autopsy.