Scientists in San Francisco may be close to finding a cure for Alzheimer’s disease. The key to their success was looking not at the brains of mice – a standard practice in scientific research – but of men.

Researchers at Gladstone Institutes, an independent biomedical research institution in San Francisco, have discovered the cause of the primary genetic risk factor for Alzheimer’s disease, and they may have found a solution to erase its damaging effects.

Their findings, published Tuesday in the journal Nature Medicine, are especially important because they conducted tests not on the brains of mice, but that of humans.

The scientists found human brains that possess even one copy of a gene, called apoE4, are more than twice as likely to develop Alzheimer’s disease in their lifetimes. Having two copies increases the risk twelvefold.

“One concern within the field has been how poorly these mouse models really mimic human disease,” said lead study author Yadong Huang, a senior investigator and director of the Center For Translational Advancement at Gladstone, in a statement. Huang noted that “many drugs work beautifully in mouse models,” but come up short in tests on human brain tissues.

To correct the accumulation of harmful proteins, the scientists looked to alter the gene that produces such proteins, apoE4. By treating the human apoE4 neurons with a structure corrector – a compound that changes the shape of the apoE4 gene to resemble a similar, but innocuous gene – the scientists restored normal function to the brain cells.

The next step is working with the pharmaceutical industry to test the structure correctors on human patients.