A BUMP on the head leading to momentary loss of consciousness may be linked to changes in the brain associated with Alzheimer's, research suggests.

Protein accumulations in the brain called beta amyloid plaques, a hallmark of Alzheimer's disease, were on average 18% higher in people with memory problems, who during their lives had suffered a concussion resulting in at least a momentary loss of consciousness.

But this only applied to people with mild cognitive impairment, a relatively minor loss of memory and thinking skills.

Study leader Dr Michelle Mielke, said that any link between Alzheimer's and concussion is a highly complex one.

The researchers conducted brain scans on 448 people aged over 70 without memory problems and 141 with mild cognitive impairment in Minnesota, US.