How do you Make the Diagnosis?

• Need to Exclude Other Causes of Dementia
• Diagnostic Criteria (Created by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer Association)
• Diagnostic Evaluation
• Mini-Mental Status Examination (MMSE)
• Brain Biopsy

Need to Exclude Other Causes of Dementia

Alzheimer's disease (AD), the most common form of dementia in older adults, accounts for about 50 to 60% of all dementias. More than four million Americans have Alzheimer's disease and this number could reach 14 million by the middle of the next century unless a cure or prevention is found. At present we do not know what causes this disease and there is no cure for it. The prevalence of AD increases with age; the rate more than doubles between the ages of 60 and 80 years (Mayeaux & Schofield, 1994). About 10 percent of adults age 65 and older have AD, but between 30 to 50 percent of those age 85 and older have the disease.

The direct (e.g. nursing care) and indirect (e.g. lost productivity of patients and family) costs of AD are estimated to cost the nation $80 to $90 billion each year. Families are the primary caregivers and bear the greatest burden of expenses.

In the early stages of AD, typical symptoms include lapses in recent memory, a decreased ability to learn new information, and a reduced attention span. As AD progressives it is characterized by progressive memory loss, language disorders (e.g., naming objects, comprehension), abnormalities in visuospatial abilities (e.g., recognizing and locating objects), impaired executive functions (e.g., judgement, calculation and abstraction), personality changes, and gait disorders.

In the late stages of the disease, patients have difficulty recognizing familiar things (e.g. family members, neighborhood). Judgement is impaired as the capacity to organize and think abstractly deteriorates. Behavioral symptoms include wandering, aggressiveness, sleep disturbances, and anxiety. In the end-stages of the disease, patients become mute, bedridden, incontinent, and completely dependent on others for their care. Delusions (false beliefs) of infidelity, theft, harm or abandonment occur in one-third to one-half of all persons with AD and often cause increased agitation and great distress to the caregiver. Hallucinations may also occur although they are less common.

The rate at which cognitive and functional decline occurs varies considerably. The average duration of AD is 10 to 12 years, however the course of AD can be as short as 18 months or as long as 27 years.

The pathological changes associated with AD include an increase in neuritic plaques and neurofibrillary tangles, and a loss of neurons and synapses. The neuritic plaques are dying nerves that contain amyloid deposits. The frequency of amyloid deposits is associated with the severity of dementia. The neurofibrillary tangles are pairs of neuronal filaments that are wrapped around each other. Although these changes are hallmarks of AD, both neuritic plaques and neurofibrillary tangles are found in many older adults who had no signs of AD.

Diagnostic Criteria (Created by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer Association)

The development of multiple cognitive (mental) deficits manifested by both of the following:

1. Memory impairment
2. One or more of the following cognitive disturbances:
   • Aphasia (language difficulties)
   • Apraxia (impairment of the ability to conduct motor activities)
   • Agnosia (failure to recognize or identify objects)
   • Disturbances in intellectual functioning (planning, organizing, abstracting)

The diagnostic evaluation can be done by a general practioner, family physician, internist, neurologist or psychiatrist. It should include a history from the patient as well as the caregiver describing the symptoms that have occurred and the previous medical history and family history of the patient. The physical examination should include a thorough neurological examination. Laboratory tests should include tests for anemia, standard metabolic screen, thyroid function, and vitamin B12 levels. Tests for syphilis and HIV should be done if there is a history and findings that relate to the possibility of these conditions. A mini-mental test and other neuropsychological tests need to be done. Other tests including EEG, MRI, CT, SPECT, EKG may be done if needed.

Mini-Mental Status Examination (MMSE)

The Mini-mental examination is a standardized approach to measuring the intellectual functioning of individuals and assessing if they have dementia.

While a brain biopsy can confirm the disease with close to 100% accuracy and differentiate Alzheimer disease from Lewy Body Dementia , it is rarely done. Instead, the diagnosis is made by excluding other conditions that produce dementia.