The latter was possible by measuring cerebrospinal fluid (CSF) concentrations of two of the disease’s biochemical hallmarks – amyloid beta42 peptide and tau protein. The researchers were thus able to detect the disease at the earliest stages, before dementia symptoms appeared and widespread irreversible damage occurred.
Homing in on a previously suggested pathological CSF biomarker signature, a team of researchers found evidence of neuron degeneration – marked by an increase in CSF concentration of tau proteins – and plaque deposition, indicated by a decrease in amyloid beta42 concentration. In addition, people with two copies of the genetic risk factor for Alzheimer’s disease, APOE ε4, had the lowest concentrations of amyloid beta42, compared to those with one or no copies.
“A safe, simple lumbar puncture can provide information to confirm suspected Alzheimer’s disease and predict the onset of the disease,” said John Q. Trojanowski, Director of the Penn Alzheimer’s Disease Core Center. Cerebral spinal fluid samples contributed by 410 volunteers at 56 sites across the U.S. and Canada were included in this study. To independently establish threshold values for these biomarkers, cerebrospinal fluid samples from 52 volunteers with normal cognition and 56 people with confirmed Alzheimer’s disease based on post-mortem autopsy diagnosis were also measured.
When compared with normal, healthy adults of the same age, a pattern of changes emerged in people with mild cognitive impairment or Alzheimer’s disease. In this group, tau concentrations increased, while amyloid beta42 levels decreased as the disease progressed.
The test was 87 percent accurate overall. In the samples from those with autopsy-confirmed Alzheimer’s disease, the amyloid beta42 concentration threshold was most sensitive and detected Alzheimer’s disease at a rate of 96.4 percent. The test accurately ruled out Alzheimer’s disease in 95.2 percent of the subjects. It positively predicted the conversion from mild cognitive impairment to Alzheimer’s disease at a rate of 81.8 percent.
MEDICA.de; Source: University of Pennsylvania School of Medicine