Applying a simple word test may help in the diagnosis of people showing early signs of Alzheimer's. One direct implication is that drug treatments, most effective in the early stages of the disease, could be prescribed earlier and to greater effect.
In a recent study 96 people with Alzheimer's disease and 40 healthy people were interviewed. All the participants were about the same age and came from the same social and cultural backgrounds. They were first asked to name all the animals they could think of in one minute. They were then asked to name all the types of fruit they could remember in one minute. The researchers found that people with early Alzheimer's were able to list only 10 to 15 words in contrast to the 20 to 25 words in the healthy group.
The Relationship Between Word Recall and Alzheimer's
During childhood we learn words at different ages. Words like cat and dog are learned before the age of 5 years whereas words like giraffe and zebra are learnt later on and used less frequently. In the study, people in the early stages of Alzheimer's consistently forgot words they learned later in their lives. The researchers found that the pattern of word loss was so consistent that they could identify people with Alzheimer's on their word 'loss' alone.
No reliable clinical methods can yet determine cognitive decline due to normal aging or Alzheimer's. One of the interesting features of this simple word task is that it involves a part of the memory system in brain not currently tested by diagnosticians. It may well be that the part of the brain in which this word loss is identified is also the part of the brain that gets most affected in the early stages of Alzheimer's disease.
The researchers are looking towards developing a new test that helps with early diagnosis of Alzheimer's that are not
currently available. During my interview with Professor Ellis he stated
"The research produced a number of interesting results. We need to see to what extent restriction to vocabulary is common to other degenerative diseases. One of the most interesting results was that the pattern of word loss was so consistent in people with Alzheimer's".
Implication for early diagnosis of Alzheimer's
Improved diagnostic screening for early Alzheimer's has a number of benefits.
Professor Ellis says the team,"are applying to funding bodies to explore the possibility of producing a useful test for early Alzheimer's that will take into account cross-cultural differences to produce a useful diagnostic tool for doctors, psychiatrists, and psychologists."
Forbes-McKay, K. E., Ellis, A. W., Shanks, M. F., & Venneri, A. (2005). The age of acquisition of words produced in a semantic fluency task is highly predictive of early Alzheimers disease. Neuropsychologia, 43, 1625-1632.