Alzheimer's disease remains one of the top neurodegenerative disorder affecting people worldwide. As part of research to provide early treatment for this brain disorder, a mouse model has been used to study its link with early bone degeneration.
Researchers from the Northeast Ohio Medical University said that their findings are important to create a detection biomarker because bone loss occurs in the early onset of the disease. This means that early diagnosis can be conducted even without brain examination.
According to the study, patients suffering from the brain disorder commonly manifest reduced bone mineral density. Osteoporosis often takes place before dementia begins. Despite these correlations, the mechanisms behind this link remain unanswered. With this, the researchers hypothesize that bone degeneration is a result of lack of serotonin production. This brain chemical is responsible for sleep and mood and is believed to be affected by Alzheimer's.
The researchers used "htau mice," which were genetically modified to have human-type tau protein in their brains. Their bone mineral density was measured before the manifestation of excessive tau production. The results showed that there was a significant loss in bone density especially in males compared to healthy mice. Further, changes in the dorsal raphe nucleus (DRN) which is a "pivotal structure in the regulation of the adult skeleton" and production of serotonin were observed.
The study concluded that bone density loss happens before brain degeneration. The scientists also revealed that changes in tau protein occur in the brainstem where serotonin-producing cells exist.
Lead researcher Christine Dengler-Crish said that "measurement of bone density, which is routinely performed in the clinic, could serve as a useful biomarker for assessing AD risk in our aging population." She added that studying the serotonin system may help in the development of potential therapies for AD.
In a separate study by the Saitama Medical University in Japan, a drug called Donepezil was found to be effective in preventing bone loss and treating Alzheimer's. Dr. Tsuyoshi said that the drug could correct bone mass while improving cognitive function. He added that "from the viewpoint of medical economics, this dual purpose could reduce the cost of treating these diseases."
Alzheimer's is the most common culprit of dementia among seniors. It is the sixth deadliest disease in the United States. People suffering from this disease lose their memories and ability to reason, think, and decide. Once the disease progresses, patients also forget to take care of themselves. Existing research only shows that the excessive accumulation of beta-amyloid and tau proteins in the brain is a hallmark of the disease. This accumulation clogs up the neurons and causes their death.