Several studies have suggested that people with Alzheimer's have reduced levels of insulin in the brain.
Insulin helps brain function and cell communication.
Researchers at The University of Washington in Seattle wanted to find out what would happen if insulin was delivered directly to the brain through the nasal passages.
Patients who got the treatment for four months showed improvement in tests of memory recall that lasted for two months.
Doctors caution this is not yet endorsed for general use, but is interesting enough for further study.