Brain imaging for measuring tau can be useful both for improving diagnosis and for developing more effective treatments, say the researchers.
“Modern brain imaging techniques offer new possibilities for predicting how the disease will develop. This is important both as an aid to diagnosis and a means of optimizing intervention for the individual patient, and for the development of drugs,"
says Konstantinos Chiotis, doctor and researcher at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, and lead author of the paper.
The Karolinska Institutet researchers previously showed, under the supervision of Professor Agneta Nordberg, that PET (positron emission tomography) scans can be used to image the distribution of tau protein in the brains of living individuals. Accumulation of tau is linked to Alzheimer’s disease.
In the latest study, 20 patients underwent a thorough examination using all existing markers for Alzheimer’s disease at Karolinska University Hospital’s cognitive clinic. They were also given a PET scan to image tau protein in their brains.
The researchers then monitored them for over four years so that their cognitive impairment could be assessed over time to find out if the amount of tau could predict the speed of deterioration.
The researchers found that the patients who had low amounts of tau protein initially demonstrated stable function during follow-up, while patients with high amounts of tau protein showed a rapid deterioration in cognitive function.
95 Percent Accuracy
The amount and distribution of tau protein in the brain could differentiate the patient groups with a precision of over 95 percent, while the precision of the existing clinical markers was at most 77 percent. The exact amount of tau also tallied well with the exact degree of deterioration on the clinical scale that is routinely used at most clinics as a measure of the cognitive function of patients with memory loss.
“Our results suggest that tau protein has a major influence on cognition. This means that drugs targeting accumulations of tau may have a better chance of changing the course of the disease than the treatments that have so far been tested and found wanting,"
says Professor Nordberg, who led the study.
Financial support for the work came from the Swedish Foundation for Strategic Research, the Swedish Research Council, the Regional Agreement on Medical Training and Clinical Research for Stockholm County Council, the Swedish Society for Medical Research, the Center for Innovative Medicine (CIMED) at Karolinska Institutet, the Loo and Hans Osterman Foundation for Medical Research, the Foundation for Geriatric Diseases at Karolinska Institutet, the Magnus Bergvalls Foundation, the Tore Nilson Foundation for Medical Research, the Sigurd and Elsa Golje Memorial, the Eva och Oscar Ahrén Research Foundation Stockholm, and the Foundation for Old Servants.
 Chiotis, K., Savitcheva, I., Poulakis, K. et al. [18F]THK5317 imaging as a tool for predicting prospective cognitive decline in Alzheimer’s disease. Mol Psychiatry (2020). https://doi.org/10.1038/s41380-020-0815-4
Image: Karolinska Institutet