Late diagnosis. This is one of the reasons neurodegenerative diseases such as Alzheimer’s are so difficult to treat. By the time patients show clinical symptoms and are diagnosed large amounts of neuronal death has occurred. This makes the development of new techniques to detect the protein deposits that cause Alzheimer’s crucial. If these proteins can be detected sooner, and treatments begun to prevent or stop their spread, the prognosis of the diseases could be improved dramatically.
Several papers recently published have described technical advances in our ability to detect these protein clumps, or aggregates. A paper published in February in Nature Communications describes the first use of antibodies to detect the aggregated amyloid β (Aβ) protein, one of the hall marks of the disease. Antibodies are used in the diagnosis of other diseases but haven’t been used in Alzeheimer’s because the blood brain barrier (BBB) prevents antibodies from crossing into the brain. By modifying the antibody to enable it to cross the BBB and using a live imaging technique called PET they could image protein aggregates in the brains of mice.
Another paper, this one published in Neuron in March describes the imaging of the second protein aggregate that defines Alzheimer’s disease, Tau. By using a compound called F-AV-1451 again in combination with PET scanning, the group imaged the brains of young and old healthy people as well as people with Alzhemier’s disease.
Brain imaging of the brains of young and old healthy brains and the brains of those diagnosed with Alzhemer’s disease. Red shows deposits of a aggregated protein Tau, one of the hallmarks of the disease. (Scholl et al, 2016)
The group were looking for certain patterns of Tau deposition in the brain, called Braak staging. A way of classifying the severity of Alzheimer’s disease described by Heiko Braak in 1991, it is performed by studying the protein deposits in the brain by autopsy following death. The group could use this scanning technique to identify the different Braak stages in the brain of live individuals.
By developing techniques to track the progression of Alzheimer’s disease in the brains of live patients could lead to better tailoring of medications to the stage of the patient’s disease, and even to faster diagnosis of this disease and earlier intervention.
Schöll M, Lockhart SN, Schonhaut DR, O’Neil JP, Janabi M, Ossenkoppele R, Baker SL, Vogel JW, Faria J, Schwimmer HD, Rabinovici GD, Jagust WJ. 2016. PET Imaging of Tau Deposition in the Aging Human Brain Neuron. 2016 Mar 2;89(5):971-82. doi: 10.1016/j.neuron.2016.01.028.
Sehlin D, Fang XT, Cato L, Antoni G, Lannfelt L, Syvänen S. (2016) Antibody-based PET imaging of amyloid beta in mouse models of Alzheimer’s disease. Nat Commun. 2016 Feb 19;7:10759. doi: 10.1038/ncomms10759