SAN DIEGO -- Alzheimer's disease is the sixth-leading cause of death in California, but scientists at San Diego State University said their research might hold the key for developing more efficient drugs.

SDSU researcher Bob Zeller and his co-workers are studying sea quirts in an effort to develop an alternative to treating Alzheimer's disease.

Sea squirts are small marine animals that some consider the closest invertebrate relative to humans.

"So far, we've got some nice prelim evidence that suggests that these animals can really process one of the proteins that is implicated in Alzheimer's disease," said Zeller.

In 2008, the Alzheimer's Association's reported over 49,500 people in San Diego County with Alzheimer's, and Zeller believes sea squirts might be a new way study the disease.

"It's actually the larvae that we studied for this particular Alzheimer's project. The larvae have simple behaviors," said Zeller, who also said one of the characteristic changes in the brains of Alzheimer's patients is the buildup of plaque.

Scientists are giving sea squirt tadpoles a protein found in families with Alzheimer's. Within 24 hours, plaque developed in the brains of the tadpoles.

"We think we've stumbled on a new, exciting area that suggests these animals might be a model for studying certain aspects of Alzheimer's disease," said Zeller.

The scientists were able to reverse the development of plaque with an experimental drug.

Zeller said they are still in the early stages but it is an important breakthrough in the treatment of Alzheimer's disease.

The SDSU study was published in the research journal "Disease Models & Mechanisms."