Risk markers could play an important role in this. These are substances linked to Alzheimer's that are found in unusually high or unusually low quantities in patients who go on to develop the disease.
Associate Professor Oskar Hansson, linked to Lund University and Skεne University Hospital in Sweden, has identified two such risk markers. He has tested these on individuals who sought treatment at the hospital's memory clinic and who displayed 'mild cognitive impairment' -- poorer memory than normal for their age.
Of the 160 subjects tested, 33 per cent developed Alzheimer's disease within five years. Sixteen per cent developed other forms of dementia, while the remaining half stayed at the level of 'mild forgetfulness'. The risk markers made a quite clear distinction between those who would later suffer from Alzheimer's and those who were not at risk.
"The 'positive connection' was 71 per cent, which is not sufficient to definitely predict who will get the disease. The 'negative connection', on the other hand, was 94 per cent, which means that it is possible to predict who in all likelihood will not get the disease," says Oskar Hansson.
Those who do not have the risk markers are therefore not at high risk of developing Alzheimer's, despite having a poor memory. They can be given this reassuring news and do not have to return for regular Alzheimer's checks.
Individuals who do not have the risk markers can also be removed from all future clinical studies of new Alzheimer's drugs.
"The studies are simpler and more correct if they are done on the right patient group from the beginning, i.e. those who really are in the risk zone for Alzheimer's disease. It is also more ethical not to include patients who are not at risk. They have nothing to gain from the medication, but may have something to lose if the drug causes side-effects," says Oskar Hansson.
The biomarkers are extracted from spinal fluid through a needle inserted into the lower spine. This is not the same as a bone marrow test, which is a much more extensive and unpleasant procedure.
Incidence of Alzheimer's disease is increasing rapidly all over the world. In Sweden there are currently around 120 000 people with the disease, but the number is expected to increase in line with the aging population. Because patients require a lot of care, Alzheimer's and other forms of dementia are estimated to cost society as much as cardiovascular disease, cancer and stroke combined.
- Joakim Hertze, Lennart Minthon, Henrik Zetterberg, Eugeen Vanmechelen, Kaj Blennow, Oskar Hansson. Evaluation of CSF Biomarkers as Predictors of Alzheimer's Disease: A Clinical Follow-Up Study of 4.7 Years. Journal of Alzheimer's Disease, 2010; 21 (4): 1119-1128 DOI: 10.3233/JAD-2010-100207
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