FRIDAY, Nov. 28 (HealthDay News) -- The adult children of people with the rarer, inherited form of Alzheimer's disease are being sought for a new study to better understand the biology of the brain disorder.

Three hundred adults with a biological parent diagnosed with a known genetic mutation causing the rare, early-onset form of Alzheimer's are needed for the six-year, $16 million study being funded by the U.S. National Institute on Aging. The Dominantly Inherited Alzheimer's Disease Network (DIAN) study aims to identify the sequence of brain changes that occur even before symptoms begin to appear. By understanding this process, researchers hope to also gain insight into the more common late-onset form of Alzheimer's.

"This collaborative, international effort will link a network of research sites in the United States, England and Australia to family members of people with these rare forms of Alzheimer's," NIA Director Richard J. Hodes said in a news release issued by the group's parent agency. "By sharing data within the network, we hope to advance our knowledge of the brain mechanisms involved in Alzheimer's, eventually leading to targets for therapies that can delay or even prevent progress of the disease."

Most Alzheimer's patients have the late-onset form of the disease, in which memory loss and other symptoms appear at age 60 or older. Only five percent have the inherited form of the disease, which takes hold in people as young as 30.

Study participant will undergo similar assessments, including genetic analysis and cognitive testing. Using that information, researchers will build a shared database of blood and cerebral spinal fluid samples and neuroimages, such as MRI and PET amyloid images.

"While three mutated genes -- amyloid precursor protein (APP), presenilin 1 and presenilin 2 -- are known causes of inherited early-onset Alzheimer's, DIAN researchers now hope to find the biomarkers, or indicators, that herald the disease at its earliest stages," NIA Division of Neuroscience Director Marcelle Morrison-Bogorad said in the news release. "By closely monitoring the biomarkers of the DIAN volunteers, both those with and those without the mutated genes, we should gain insight into the underlying pathology behind both early- and late-onset forms of the disease."

People interested in participating in the DIAN study should visit www.dian-info.org. Study participants must be aged 18 or older.

More information

The U.S. National Institute on Aging has more about Alzheimer's disease.