Lumbar punction is an important tool for the early diagnosis of Alzheimer's disease
[Press release, 24 June 2009] The personal experience of patients' forgetfulness in everyday life combined with a sample of cerebrospinal fluid may be two important tools in the detection of Alzheimer's disease as early as possible. This is the conclusion of a study that has been published in Lancet Neurology, in which scientists from the Karolinska Institutet have followed patients with various forms of mild cognitive impairment for three years using, among other tests, analysis of cerebrospinal fluid.
Alzheimer's disease is characterised by a lowered concentration of the peptide Abeta42 and high levels of the tau proteins in the cerebrospinal fluid. Similar changes have been found to be common in patients with mild amnestic cognitive impairment (impaired memory), without these patients having being diagnosed with dementia. But the occurrence of changes similar to those found in patients with Alzheimer's disease in patients with subjectively experienced mild cognitive impairment or non-amnestic mild cognitive impairment has not previously been known.
The study that has now been published describes how scientists at the Karolinska Institutet, in collaboration with several other European universities, have investigated the occurrence of changes similar to those seen in Alzheimer's disease in the cerebrospinal fluid from patients with mild cognitive impairment. They have also examined how these proteins correlate with memory impairment in patients with amnestic mild cognitive impairment (aMCI), subjective mild cognitive impairment (SCI) and non-amnestic mild cognitive impairment (naMCI). The patients in the study were recruited from 20 memory clinics throughout Europe and matched against a control group of healthy people. The study lasted for three years, with follow ups every year. The scientists analysed the cerebrospinal fluid for the markers Abeta42 and tau protein, and they analysed the cognitive profile of the subjects with respect to such qualities as memory impairment, daily activities, and - where relevant - development towards a diagnosis of Alzheimer's disease.
The study shows that Alzheimer's disease is the most common diagnosis based on samples of cerebrospinal fluid from those in the groups of patients with SCI, naMCI and aMCI, principally coupled with memory impairment in the groups with naMCI and aMCI. Patients with SCI can show very early stages of Alzheimer's disease, but an objective cognitive impairment that can be measured may only become apparent after a long period of observation. The scientists believe that the changes in the cerebrospinal fluid can be used as a prognostic marker for patients with aMCI and naMCI. The study must, however, be repeated, in order to validate the results.
"It's important to start treatment of Alzheimer's disease early, in order to achieve as effective a treatment as possible. The new treatments that are available can start to be used earlier in the process, before the disease has become manifest", says Yvonne Freund-Levi, one of the scientists behind the study.
Prevalence and prognostic value of CSF markers of Alzheimer's disease pathology in patients with subjective cognitive impairment or mild cognitive impairment in the; a prospective cohort study
Neurology, Jul;8(7):619-27, Epub 2009 Jun 10.