Tests and diagnosis for Alzheimer's disease
Alzheimer's disease is not simple to diagnose - there is no single test for it. For this reason, the first thing doctors do is to rule out other problems before confirming whether mental signs and symptoms are severe enough to be a kind of dementia or something else.
Doctors may:
Take a history (ask about symptoms and daily activities)Do a physical examination to find any signs of, for example, a stroke, heart condition or kidney disease, andCheck neurological function, e.g. by testing balance, senses and reflexes.
Depending on what the doctor thinks could need checking, other diagnostics are:
Sending off for tests of blood and urine samplesArranging brain scans (possibly including CT,MRIIand EEG).
Sometimes dementia symptoms are related to an inherited disorder such as Huntington's disease so genetic testing may be done. For some, an assessment for things such as depression can also be carried out.3
Again though, the above early tests are not for diagnosing Alzheimer's disease itself, but for ruling out other problems before starting to narrow down to dementia caused by AD. Central to this is checking memory loss and mental performance (cognitive testing).
There must be memory loss and an impairment in one other area of cognition for a diagnosis of dementia such as Alzheimer's to be made. These criteria also need to be progressive (a worsening compared with how the person has been before), and severe enough to affect
Cognitive tests have changed little since being established by work from the likes of Professor Henry Hodkinson in the 1970s. The following example list of questions reveals the types of memory loss and areas of cognition that are tested and may indicate Alzheimer's.15
The "abbreviated mental test score" (AMTS):
What is your age? What is the time, to the nearest hour? Repeat an address at the end of the test that I will give you now (e.g. "42 West Street") What is the year? What is the name of the hospital or town we are in? Can you recognize two people (e.g. the doctor, nurse, home help, etc.)? What is your date of birth? In what year did World War 1 begin? (Other widely known dates in the past can be used.) Name the president/prime minister/monarch. Count backwards from 20 down to 1.
The general practitioner assessment of cognition (GPCOG) test is a website-based assessment designed to be an early reliable indicator for use in initial consultations with GPs.16,17
The mini mental state examination (MMSE) is a fuller cognitive test to help diagnose Alzheimer's disease. It is also sensitive to the severity of the disorder and helps to indicate when drug treatment could ease symptoms appearing later in the course of the disease:17,18
Normal cognitive health - score above 26Mild-to-moderate Alzheimer's - below 26Moderate - below 20 but above 10Severe - score under 10.
It is always worthwhile for people with concerns about their own or someone else's possible dementia to get the problem thoroughly checked by a doctor, both because of the mental confusion created by the symptoms and because they may be due to something else that needs checking and treating.17,19
Is there a biological test for Alzheimer's disease?
There is no simple biological test specifically for Alzheimer's disease that can be used by doctors, which is why all the diagnostic options are designed to rule out other explanations for the dementia before confirming Alzheimer's as the cause.
A genetic test is possible in some settings to indicate the likelihood of someone having or developing the disease but this is controversial and not entirely reliable.11,14 A gene known as the APOE-e4 is associated with higher chances of people over the age of 55 years developing Alzheimer's.20
The question of future biological tests is being intensely investigated by medical research. A lot of clues as to the biological changes in the brain have been uncovered by neuropathology work on brains examined at autopsy after death.12 This and other types of research may result in future tests to measure new biomarkers.
Genetic testing may become a more realistic option, too - so long as researchers continue to find reliable links as they discover new gene associations.
Genetic testing is not always a welcome idea though. The Alzheimer's Association's position APOE-e4 testing for example, is that it should not be used routinely and that there should not be prejudiced treatment in terms of insurance and so on when it is used as an indication.20
In research studies, any genetic results used as indicators of disease would not be identifiable by individual - they would be anonymized.
Recent developments in tests and diagnosis from MNT news
A small study published in August 2013 in the Journal of the Neurological Sciencesfound interesting differences in ability to smell peanut butter between people with Alzheimer's disease versus those with different kinds of dementia.
A person's risk of Alzheimer's disease could be predicted through a simple saliva test, according to the results of a new study.
A team of researchers at King's College London in the UK has announced the development of a "gene signature" that could help predict conditions such as Alzheimer's disease years before symptoms arise.
According to new research, a noticeable change in what makes us laugh may not be a good sign for cognitive health: it may be an early indicator for dementia.
Inflammatory brain changes related to Alzheimer's disease may occur as many as 20 years before onset of symptoms, according to new research - a finding that could pave the way for early interventions that could halt disease development.
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