Elderly patients hospitalized for hip fracture surgery also carried biomarkers of developing Alzheimer’s disease despite no clinical evidence of dementia, according to a new study conducted by researchers at Johns Hopkins University School of Medicine and published in PLOS ONE.
Johns Hopkins researchers discovered biomarkers of Alzheimer’s disease in most of the hip-fracture patients’ spinal fluid samples, adding to the evidence that brain alterations that lead to poor balance in older people may underpin both increased risk of hip-fracturing falls and Alzheimer’s disease, and that hip fracture itself may therefore serve as a first sign of undiagnosed disease.
“… many of our study participants were active and living independently without overt signs of Alzheimer’s disease,” said Esther Oh, M.D., Ph.D., associate professor of medicine at the Johns Hopkins University School of Medicine and associate director of the Johns Hopkins Memory and Alzheimer’s Treatment Center. However, she cautioned that this study should not be used to suggest that all hip-fracture patients also carry Alzheimer’s biomarkers or should they have their spinal fluid tested for them. However, it would be wise, Oh said, to monitor patients who have experienced a hip repair surgery after a fall for signs of post-operative delirium or other mental or cognitive problems during recovery.
Oh noted that several international studies have shown that up to a quarter of older adults hospitalized for hip fracture surgery are likely to die within the following year, results suggesting that a serious medical condition may have been simmering undiagnosed prior to the falls that sent them to the hospital.
Testing for Alzheimer’s disease biomarkers is not covered by Medicare and isn’t routinely performed on older adults. It can be done by an amyloid PET scan or by using biomarkers from spinal fluid, such as in this study. The PET scan test costs at least $3,000. The spinal fluid analysis is still mostly used for research, although it is commercially available in some laboratories.
Oh’s new study was in part a response to results of research published late 2018 in JAMA Surgery by Johns Hopkins researchers, which showed that 34 percent of hip fracture patients develop delirium during their hospital stay, a condition characterized by restlessness, delusions and incoherent thoughts and speech. Because patients with Alzheimer’s disease are more likely to experience these symptoms, and because of the higher than normal mortality rate associated with hip fracture compared with other surgeries, Oh and her team designed their study to directly test hip fracture patients for Alzheimer’s disease biomarkers.
For the research, the Johns Hopkins team recruited 200 hip fracture patients admitted to The Johns Hopkins Hospital and Johns Hopkins Bayview Medical Center from November 2011 to May 2016. Participants were an average of 82 years old, ranging from 65 to 102. Most of the participants, 74 percent, were women. Some 96 percent were white. The study also only included hip fracture patients who had received spinal (local) anesthesia before surgery so that spinal fluid samples could be collected at the time of anesthetic injection.
In 168 of the patients, the spinal fluid samples were tested for elevated levels of commonly accepted biomarkers of Alzheimer’s and other neurodegenerative diseases. The biomarkers included the proteins amyloid beta 42 (Aβ42), Aβ40, tau, and tau with a phosphate chemical group attached (p-tau). The amyloid proteins and tau are found in hallmark, tangled clumps in nerve cells, and in plaques that form in the brains of people with advanced Alzheimer’s. High levels of p-tau indicate brain injury or other types of brain cell damage.
