Many people develop depression in the latest stages of life, but until now doctors had no idea that it could point to a build up of a naturally occurring protein in the brain called beta-amyloid, a hallmark of Alzheimer’s disease. In fact, late-life depression could become a major risk factor for developing Alzheimer’s faster than others, according to research unveiled at the Society of Nuclear Medicine and Molecular Imaging’s 2014 Annual Meeting.
Alzheimer’s disease 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. Depression has been proven to
have its own neurodegenerative effects on the brain, but here researchers have
found an undeniable connection between beta-amyloid in depressed elderly
patients with cognitive deficits and advancement to Alzheimer’s disease. They
were able to prove this using molecular imaging data from a global dementia
imaging database.
“Our results clearly
indicate that mild cognitively impaired subjects with depressive symptoms
suffer from elevated amyloid-levels when compared with non-depressed
individuals,” said the study’s principal scientist Axel Rominger, MD, from the
department of nuclear medicine at the University of Munich in Germany. “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.”
The study involved 371
patients 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, which includes data from at least 55 research centers across the U.S.
and Canada now readily available to more than 2,500 researchers worldwide.
Results showed that 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,” said co-author and fellow researcher Matthias Brendel. Additionally,
knowing the risk could help patients make necessary lifestyle changes and
prepare their families.
Alzheimer’s disease is the
most prevalent form of dementia. It is estimated that 44.4 million people are
living with dementia worldwide. This number is expected to increase to
approximately 75.6 million in 2030 and 135.5 million in 2050, according to 2013
data from the Alzheimer’s Disease International.
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