The presence of four misfolded proteins linked to neurodegeneration is common in the brains of older adults and is associated with dementia and impaired cognition, researchers say.

The misfolded proteins — tau neurofibrillary tangles, amyloid-beta, alpha-synuclein, and transactive response DNA-binding protein 43 (TDP-43) — are often seen in older brains, they write in JAMA Neurology.

But few studies have investigated the phenotype of “quadruple misfolded proteins”, or QMP, as Dr Erin Abner and colleagues at the University of Kentucky, US, named the coexistence of all four proteinopathies.

To describe this phenotype, including the trajectories of global cognition, the team used brain-autopsy data from 375 people who had participated in a longitudinal community-based cohort study of ageing and dementia conducted by the University of Kentucky Alzheimer’s Disease Research Center.