Jun 10, 2014 11:59 AM EDT By Jaleesa Baulkman, UniversityHerald Reporter

Older people who are depressed may have a higher risk of developing Alzheimer's faster than others, according to a recent study.

Researchers found that people who develop Alzheimer's in the latest stages of life could lead to the buildup of a naturally occurring protein in the brain called beta-amyloid, a hallmark of Alzheimer's disease.

 Alzheimer's disease, the most prevalent form of dementia, is a currently incurable neurodegenerative disease with marked protein aggregates including beta-amyloid and tau. The disease begins developing years before noticeable cognitive decline and memory loss. Previous studies have proven that depression has its own neurodegenerative effects on the brain. It is estimated that 44.4 million people are living with dementia worldwide.

"Our results clearly indicate that mild cognitively impaired subjects with depressive symptoms suffer from elevated amyloid-levels when compared with non-depressed individuals," Axel Rominger, the study's principal scientist, said in a statement. "The combination of elevated amyloid-levels and coexisting depressive symptoms constitute a patient population with a high risk for faster progression to Alzheimer's disease."

For the study, researchers recruited more than 350 people with mild cognitive impairment who underwent PET imaging with the radiotracer F-18 florbetapir and magnetic resonance imaging (MRI) chosen retrospectively from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database.

Based on their findings, mild cognitive impaired patients with depressive symptoms had higher amyloid deposition than non-depressed controls as indicated by the binding of the radiotracer to amyloid particularly in the frontal cortex and the anterior and posterior cingulate gyrus of the brain, both involved in mood disorders such as depression.

"Therapeutic options for Alzheimer's disease are still limited and therefore the identification and understanding of contributing risk factors that influence the disease are crucial in ongoing research as they offer the possibilities for future medical intervention," Matthias Brendel, co-author of the study and fellow researcher, said in a statement.

Additionally, knowing the risk could help patients make necessary lifestyle changes and prepare their families.

The findings were recently unveiled at the Society of Nuclear Medicine and Molecular Imaging's 2014 Annual Meeting.

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