A specific type of immune cell, called microglia (green) can help contain amyloid plaques (magenta), the key hallmark of Alzheimer’s disease, thus limiting their damage to surrounding brain cells.

But, Dr Jaime Grutzendler, associate professor of neurology and neuroscience at Yale, said that is no longer thought to be the case, and should signal a new.

He said: ‘It suggests we should be enhancing the function of these immune cells, not trying to suppress it.’