Diagnosis of Alzheimer’s disease

Assessment of a patient with Alzheimer’s disease, usually involves a team of doctors consisting of a neurologist, psychiatrist and neuro-psychologist, assisted by a radiologist and a pathologist. Assessment involves a series of steps and can take several days to complete. There is no single test which confirms or excludes Alzheimer’s disease.

Steps in the diagnosis of Alzheimer’s disease

There are three steps in the diagnosis of Alzheimer’s disease:

• Documentation of loss of intellectual function
• Documentation that the loss of intellectual function is disabling the patient in daily activities
• Exclusion of other causes of loss of intellectual function

Step 1: In evaluating a patient, the physician will need to check if there is a substantial deterioration in the intellectual function of the aged person relative to his/her previous status, who otherwise seems to be in good physical condition. In medical terms, it is necessary to seek evidence of “dementia”.

Doctors will administer neuropsychological tests to check various components of intellectual function. Examples of such tests are the Fuld Object Memory Test in which patients are shown 10 objects and then asked to memorise this list of objects and repeat it to the examiner. An average healthy adult should be easily able to recall seven to eight objects. However, patients of Alzheimer’s disease can recall only one or two objects. Another neuropsychological test is the Boston Naming Test in which subjects are shown various objects and asked to name them. Most healthy people can easily name these objects, while patients with Alzheimer’s disease have trouble naming even such simple objects as a comb or a pen. Similarly, there are neuropsychological tests for speech, calculation, problem-solving and judgement. Based on the results of these tests, loss of intellectual functions can be documented.

Step 2: The doctor needs to ensure that the loss of intellectual functioning is severe enough to disable the person in activities of daily living. Patients of Alzheimer’s disease are extremely disabled in function. When loss of intellectual function is so severe that it leads to disabilities, conditions for Step 2 in the diagnosis of Alzheimer’s disease are met.

Step 3: In the diagnosis of Alzheimer’s disease, it is important to exclude other causes of loss of intellectual function. For this purpose, doctors will take a detailed history of the patient’s illness from their relatives, then conduct a comprehensive medical, neurological and neuropsychological examination. Blood tests and X-ray tests, such as CT scan and MRI scan, will help to exclude conditions such as thyroid disease, brain tumour or stroke. In Alzheimer’s disease, CT and MRI scans show a shrinking of the brain. This is medically referred to as “cortical atrophy”.

If Alzheimer’s disease is diagnosed, the family should collectively decide on several issues of management or treatment of the patient as well as on the patient’s rights, aspirations and legal interests.

Source: World Health Organisation