Medical Bulletin 16/ March/ 2024

According to a new study from the University of Colorado Anschutz Medical Campus, managing circadian rhythms through intense light and chronologically timed therapy can help prevent or treat a variety of circulatory system conditions including heart disease.

The findings of the study was published in the Journal Circulation Research.

"The impact of circadian rhythms on cardiovascular function and disease development is well established," said the study's lead author Tobias Eckle, MD, PhD, professor of anesthesiology at the University of Colorado School of Medicine. "However, translational preclinical studies targeting the heart's circadian biology are just now emerging and are leading to the development of a novel field of medicine termed circadian medicine."

The study reviewed current circadian medicine research, focusing on the use of intense light therapy following surgery, utilizing light to treat cardiac injury, exploring how cardiovascular disease can differ between men and women and administering drugs at specific times of day to coincide with the body's internal clock to speed healing.

The results showed that when light therapy was used on patients after surgery positive results were observed, including lower levels of troponin, a key protein whose elevation can signal a heart attack or stroke.

The findings indicated that circadian rhythms influence cardiovascular function, with blood pressure and heart rates peaking during the day and dropping at night. Any disruption can worsen heart conditions and could lead to worse cardiovascular disease outcomes including myocardial infarction and heart failure.

Therefore, intense light therapy is used for post-surgery recovery and for guarding against injury, hence, reducing cardiac issues. Light exposure also triggers brain signals that regulate rhythms, stabilizing genes and blocking irregular heart rhythms.

"Circadian rhythms play a crucial role in cardiovascular health, influencing the timing of onset and severity of cardiovascular events and contributing to the healing process from disease. Studies in humans are clearly required. Regarding intense light therapy, chronotherapy and restricted feeding are low-risk strategies that should be tested sooner than later." concluded Eckle.

Reference: Eng H. Lo, Frank M. Faraci. Circadian Mechanisms in Cardiovascular and Cerebrovascular Disease. Journal: Circulation Research, 2024; 134 (6): 615 DOI: 10.1161/CIRCRESAHA.124.324462

In a study published in the Journal Immunity, researchers from the Perelman School of Medicine at the University of Pennsylvania revealed that the antibody responses to new SARS-CoV-2 variant infections and vaccinations are powerfully shaped by prior exposures to earlier SARS-CoV-2 vaccines.

The researchers analyzed antibody responses in people infected with or vaccinated against the relatively new SARS-CoV-2 variants BA.5 and XBB and found that even though BA.5 and XBB are very different from the original “ancestral” version of SARS-CoV-2, the responses to these newer variants came almost entirely from the B cell repertoire that was already in place due to prior vaccinations against the ancestral strain.

“Detailing how SARS-CoV-2 immune history influences the antibody response to new variants, through studies such as this one, will ultimately help us design more effective vaccines,” said study co-senior author Scott Hensley, PhD, a professor of Microbiology at Penn Medicine.

The study investigated how prior exposure influences antibody responses to SARS-CoV-2 variants BA.5 and XBB, both highly transmissible and differing significantly from the original virus. Boosters targeting these variants were introduced in 2022 and 2023.

“Prior vaccinations are highly beneficial for establishing memory B cells that can be rapidly recruited to produce neutralizing antibodies against new SARS-CoV-2 variants,” said Hensley.

Researchers found that individuals who initially had lower numbers of B cells elicited by the ancestral variant were more likely to produce totally new, variant-specific antibodies. More importantly, people who had high numbers of B cells against the ancestral SARS-CoV-2 strain were more likely to mount effective immune responses, which were mostly cross-reactive, to the BA.5 and XBB variants.

The main implication of the findings was that immunological imprinting from the original ancestral SARS-CoV-2 strain had a significant impact on the antibody responses to the BA.5 and XBB variants and boosters based on them. These responses still appear to be protective, but it is unclear that that protection will remain robust as SARS-CoV-2 variants continue to evolve.

“Most people alive today have been immunologically imprinted by ancestral SARS-CoV-2, but that will inevitably change as time goes on. We need to continue studying how different prior exposures impact immunity to new variants that come down the road, and how this immunity affects viral evolution.” concluded Hensley.

Reference: Timothy S. Johnston, Shuk Hang Li, Mark M. Painter, Daniel C. Douek, E. John Wherry, Scott E. Hensley; Journal: Immunity; DOI: 10.1016/j.immuni.2024.02.017

According to a new study at Columbia University Mailman School of Public Health and The Robert Butler Columbia Aging Center, a healthier diet is associated with reduced dementia risk and slower pace of 

The study was published in the Journal Annals of Neurology.

Nutrient-rich foods provide antioxidants that combat oxidative stress, which contributes to aging and neurodegenerative diseases like dementia. Additionally, a balanced diet supports brain health by reducing inflammation, promoting proper blood flow, and supplying essential nutrients that aid cognitive function and neuronal repair.

“Much attention to nutrition in dementia research focuses on the way specific nutrients affect the brain” said Daniel Belsky, PhD, associate professor of Epidemiology at Columbia School of Public Health and the Columbia Aging Center, and a senior author of the study. “We tested the hypothesis that healthy diet protects against dementia by slowing down the body’s overall pace of biological aging.”

For the study, researchers analyzed 1,644 participants for nine examinations, approximately every 4 to 7 years. At each follow-up visit, data collection included a physical examination, lifestyle-related questionnaires, blood sampling, and neurocognitive testing.

Of all the participants included in the analyses, 140 of the participants developed dementia. To measure the pace of aging, the researchers used an epigenetic clock called Dunedin-PACE developed at Duke University and the University of Otago.

“We have some strong evidence that a healthy diet can protect against dementia,” said Yian Gu, PhD, associate professor of Neurological Sciences at Columbia University Irving Medical Center and the other senior author of the study, “But the mechanism of this protection is not well understood.” Past research linked both diet and dementia risk to an accelerated pace of biological aging.

The findings suggested that slower pace of aging mediated part of the relationship of healthy diet with reduced dementia risk, and therefore, monitoring pace of aging may inform dementia prevention. However, a portion of the diet-dementia association remains unexplained, therefore continued investigation of brain-specific mechanisms is in well-designed mediation studies is needed.

“We suggest that additional observational studies be conducted to investigate direct associations of nutrients with brain aging, and if our observations are also confirmed in more diverse populations, monitoring biological aging, may indeed, inform dementia prevention,” said Belsky.

Reference: Aline Thomas PhD, Calen P. Ryan PhD, Avshalom Caspi PhD, Zhonghua Liu PhD, Terrie E. Moffitt PhD, Karen Sugden PhD, Jiayi Zhou MPH, Daniel W. Belsky PhD, Yian Gu MD, PhD; Journal: Annals of Neurology; DOI: 10.1002/ana.26900