Three new studies shed light on the role of cardiac health in developing Alzheimer disease, depression, anxiety, and dementia.
Three new studies in geriatric psychiatry show the how treating two heart disease conditions-atrial fibrillation and arterial stiffness-and monitoring brain levels of an antioxidant may affect the risks of dementia: atrial fibrillation patients may have an increased risk of dementia, but anticoagulants appear to reduce that risk; arterial stiffness is a good proxy for predicting who will go on to develop dementia; and brain levels of an antioxidant may help monitor progression to Alzheimer disease (AD).
Atrial fibrillation leads to a faster global cognitive decline and an increased risk of dementia in older people, but the use of anticoagulant drugs may reduce the dementia risk. A population-based cohort study included 2,685 dementia-free participants, average age 73 years, from the Swedish National Study on Aging and Care in Kungsholmen, who were regularly examined from 2001–2004 to 2010–2013. Some 243 participants (9.1%) had atrial fibrillation at baseline.
During a 9-year follow-up, 279 participants (11.4%) developed atrial fibrillation and 399 (14.9%) developed dementia. As a time-varying variable, atrial fibrillation was significantly associated with a faster mental decline and an increased hazard ratio of all-cause dementia and vascular and mixed dementia, but not AD. Among those with either prevalent or incident atrial fibrillation, the use of anticoagulant drugs, but not antiplatelet treatment, was associated with a 60% decreased risk of dementia.
Clinical Implications for Study 1. “Compromised blood flow caused by atrial fibrillation may affect the brain in a number of ways. We know as people age, the chance of developing atrial fibrillation increases, as does the chance of developing dementia. Our research showed a clear link between the two and found that taking blood thinners may actually decrease the risk of dementia,” said senior author Chengxuan Qiu, PhD, of the Karolinska Institute and Stockholm University in Sweden.
Ding M, et al. Atrial fibrillation, antithrombotic treatment, and cognitive aging. Neurology. Oct 2018, 10.1212/WNL.0000000000006456; DOI: 10.1212/WNL.0000000000006456
Aortic stiffness, measured by carotid-femoral pulse wave velocity, independently predicts incident dementia in older adults. The association between arterial stiffness and dementia was investigated in 356 older adults, average age 78 years, who were part of the Cardiovascular Health Study Cognition Study, a long-term study to identify dementia risk factors. All participants included in the present study were dementia-free when the study started in 1998.
Participants with high pulse wave velocity readings, a noninvasive measure of the speed at which the blood pressure pulse travels through the arteries, were 60% more likely to develop dementia during the following 15 years compared with those with lower pulse wave velocity values. Although arterial stiffness is correlated with subclinical brain disease and risk factors for cardiovascular disease, these confounding variables did not explain the results.
Clinical Implications for Study 2: “As the large arteries get stiffer, their ability to cushion the pumping of blood from the heart is diminished, and that transmits increased pulsing force to the brain, which contributes to silent brain damage that increases dementia risk. Although arterial stiffness is associated with markers of silent, or subclinical, brain damage and cognitive decline, until now, it was not clear that arterial stiffness was associated with the risk of dementia,” said senior author Rachel Mackey, PhD, MPH, assistant professor of epidemiology, University of Pittsburgh Graduate School of Public Health. “What’s exciting to think about is that the strong association of arterial stiffness to dementia in old age suggests that even at age 70 or 80, we might still be able to delay or prevent the onset of dementia.”
Cui C, et al. Aortic Stiffness is Associated with Increased Risk of Incident Dementia in Older Adults. J Alzheimers Dis. 2018;66:297-306.
Brain levels of the antioxidant glutathione may be another measure to help diagnose the potential for the advance of AD. Using magnetic resonance spectroscopy, non-invasive imaging techniques, Shukla and colleagues found that glutathione has two conformations (closed and extended forms) in the brain. When glutathione is depleted in the hippocampus regions of an elderly person, a healthy brain suffers mild cognitive impairment. Now this has been correlated with depletion of the closed form of glutathione in patients with AD.
It is unknown to what extent the lower levels of extended form of glutathione in those suffering from Alzheimer’s disease can be measured, but the finding opens the possibility for further clinical observation using glutathione as supplement to combat the advancement of AD.
Clinical Implications for Study 3: “If routine non-invasive tests for lower levels of glutathione in the hippocampus regions are performed, we might be able to mitigate the advancement of Alzheimer’s disease by providing glutathione supplements,” said co-author Pravat K. Mandal of the National Brain Research Centre in Gurgaon, India. An observational study is planned, he said.
Shukla D, et al. A Multi-Center Study on Human Brain Glutathione Conformation using Magnetic Resonance Spectroscopy. J Alzheimers Dis. 2018 Sep 1. doi: 10.3233/JAD-180648.