Tau PET imaging may be the key to discovering effective drugs for Alzheimer’s disease, according to a new case study from Lund University in Sweden. Until now, it has not been known how well this new imaging method depicts the actual changes in a brain affected by the disease.

Tau accumulates in the brains of individuals with Alzheimer’s and gradually kills brain cells. Amyloid beta was previously the focus of Alzheimer’s research, but in recent months it has been discovered that tau is a better indicator of cognitive decline.

This new case study has allowed researchers to compare tau PET images and brain tissue from the same individual for the first time. The brain tissue came from someone who died after recently undergoing a tau PET imaging exam.
They found that tau PET can improve diagnostics, but also that it can be used to help develop new drugs to treat Alzheimer’s. New candidate drugs aim to reduce the accumulation of tau and the new imaging method can investigate how tau is affected by the drug.

Tau PET was a major focus at this year’s Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2016 annual meeting. A German team of researchers received the SNMMI Image of the Year Award for their image that showed the correlation between amyloid, tau aggregation and metabolic activity in those with Alzheimer’s.

“Adding tau-imaging may help us now to understand factors leading to the actual onset of neurodegeneration and possibly also to document effective treatment,” Dr. Alexander Drzezga, professor and chair in nuclear medicine at the University of Cologne, Germany, told HCB News.

A PET imaging agent for assessing tau called [18F]MK-6240 is on the horizon. Enigma Biomedical Group Inc. announced a collaboration with Biogen Inc. and Merck to validate and clinically qualify the investigational imaging agent.

They will test how well the imaging agent evaluates the status and progression of neurofibrillary tangles (NFTs) in the brain. NFTs that consist of aggregated tau protein are a hallmark of several neurodegenerative diseases including Alzheimer's.

One of the criticisms of the research from Lund University is that it only studied a single case. However, since there are areas in the brain that accumulate a lot of tau and others with less tau its sufficient to examine one individual in order to verify if the imaging method is effective.

Going forward, the researchers are focusing on tracking the aggregation of tau in the brain over time, and connections with diagnostics using spinal fluid samples. Tau PET imaging may also hold potential for frontal lobe dementia and Parkinson’s-like diagnoses such as progressive supranuclear palsy and corticobasal degeneration.

The study was published in the journal, Brain, and was funded by the European Research Council, the Swedish Research Council, the Swedish Alzheimer’s Fund and the Swedish Brain Fund, among others.

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