There is growing consensus that the cytotoxic species in the aggregation process is a ring-shaped oligomer which forms early in the process and binds to and permeabilizes the membranes of neuronal cells.

Now scientists at the Interdisciplinary Nanoscience Center iNANO in Denmark - which is run jointly by Aarhus University and Aalborg University - have identified an early and a mature state of such an oligomer, shedding further light on the formation of this elusive species. They described their research in Nanotechnology.

Using the 29-residue peptide hormone glucagon from Novo Nordisk A/S as a model system, the scientists found that a few hours of incubation led to the formation of doughnut-shaped structures with a hole in the middle. These structures later filled out to form a more solid disc. And the solid disc appears to be the precursor for the needle-shaped fibrils.

The scientists hope that more information about how these oligomers form and change to other structures may allow them to understand how to control and prevent their formation, and thus ultimately stop the progression of dementia.