Drugs used to calm inflammation in psoriasis may also help to combat the effects of Alzheimer's disease, a study on mice suggests.
Tests showed the short-term memory of the animals improved when given similar drugs, according to a study published in the journal Nature Medicine.
The build-up of proteins thought to destroy brain cells was also reduced.
Alzheimer's Research UK said brain inflammation was looking like a "key player" in the disease.
Psoriasis is an inflammatory disorder caused when the immune system attacks healthy skin cells, stimulating the production of new skin.
The immune system, which controls levels of inflammation, has been implicated in both Alzheimer's disease and psoriasis.
However, the exact cause of the gradual destruction of the tissues of the brain during Alzheimer's disease is still unknown.
Researchers at the University of Zurich, in Switzerland, and the Charite university hospital, Germany, targeted two components of the immune system known to boost inflammation in mice genetically programmed to develop Alzheimer's.
Injecting an antibody to attack the two chemicals, twice a week once the mice were one month old, led to a 31% reduction in beta-amyloid plaques, which are thought to damage the brain.
Similar tests on older mice, which had already developed symptoms, showed "the significant deficit in short-term memory" was reduced "substantially", the report said.
Drugs which target the same system have already been tested on people with psoriasis.
The authors said: "Based on the safety data in patients, clinical studies could now be implemented without delay. Now, the goal is to bring the new therapeutic approach to Alzheimer patients quickly."
Dr Simon Ridley, head of research at Alzheimer's Research UK, said: "There is increasing evidence that inflammation is a key player in Alzheimer's and it is an exciting area for researchers working to defeat this devastating disease.
"This promising research adds further support for the role of the immune system in Alzheimer's, linking two inflammatory proteins to the disease in mice.
"Early studies like these are crucial to help highlight new targets for drug development, but we need to be careful not to assume that what is true for mice is true for men. Before any new Alzheimer's drug can reach patients, first it must be rigorously tested in clinical trials."