Medical Bulletin 21/ March/ 2024

A new study led by researchers at McLean Hospital (a member of Mass General Brigham) and Washington State University have demonstrated that naturally occurring glucose fluctuations impact cognitive function in people with Type 1 Diabetes (T1D).

The study published in the journal npj Digital Medicine, revealed that cognition was slower in moments when glucose was atypical – that is, considerably higher or lower than someone’s usual glucose level. However, some people were more susceptible to the cognitive effects of large glucose fluctuations than others.

T1D is an autoimmune disease characterized by glucose variability. Previous laboratory studies have shown that very low and very high glucose levels impair cognitive function. However, technological limitations made it difficult to study the impact of naturally occurring glucose fluctuations on cognition outside of the laboratory, preventing researchers from obtaining repeated, high-frequency measurements within the same individuals over time. High-frequency measurements are necessary to understand whether glucose fluctuations impact cognition similarly for everyone.

In the study, researchers collected high-frequency glucose and cognitive data from 200 individuals with T1D using digital glucose sensors and smartphone-based tests. Glucose levels were measured every five minutes, and cognitive assessments were conducted three times daily for fifteen days. This data collection allowed researchers to analyze the cognitive effects of natural glucose fluctuations. Utilizing machine learning, they investigated individual differences in the impact of glucose on cognition.

The results showed that cognitive function was impaired when glucose was considerably higher or lower than usual. The researchers also found that people differed from each other in terms of how much glucose fluctuations impacted their cognitive speed, and some people – including older adults and adults with certain health conditions – were much more impacted by glucose fluctuations than others.

“Our results demonstrate that people can differ a lot from one another in how their brains are impacted by glucose. We found that minimizing glucose fluctuations in daily life is important for optimizing processing speed, and this is especially true for people who are older or have other diabetes-related health conditions,” said Laura Germine, PhD, co-senior author of the paper and director of McLean’s Laboratory for Brain and Cognitive Health Technology.

Reference: Z. W. Hawks, E. D. Beck, L. Jung, L. M. Fonseca, M. J. Sliwinski, R. S. Weinstock, E. Grinspoon, I. Xu, R. W. Strong, S. Singh, H. P. A. Van Dongen, M. R. Frumkin, J. Bulger, M. J. Cleveland, K. Janess, Y. C. Kudva, R. Pratley, M. R. Rickels, S. R. Rizvi, N. S. Chaytor & L. T. Germine; Dynamic associations between glucose and ecological momentary cognition in Type 1 Diabetes; Journal: npj Digital Medicine; DOI: 10.1038/s41746-024-01036-5

Rheumatic diseases linked to childbearing problems, finds study

A new study published in the journal Rheumatology, published by Oxford University Press, found that rheumatic diseases can lead to reproductive problems, though some conditions have more detrimental effects than others.

Immune-mediated diseases encompass a diverse range of conditions, all characterized by abnormal immune system activity. While some, like type 1 diabetes, typically manifest before reproductive age, others emerge later in life. Scientists have investigated systemic lupus erythematosus for its effects on reproductive health as the condition increases the risk for some adverse pregnancy outcomes, including pre-eclampsia, preterm delivery, C-sections, and low birth weight. However, the impact of other autoimmune diseases—such as psoriasis—on fertility and pregnancy is unclear.

In the study, researchers used data from Finnish nationwide health registers to study the impact of immune-mediated diseases on reproductive health measures such as reproductive success, and for women, ever having experienced adverse maternal and perinatal outcomes. Out of all people born in Finland between 1964 and 1984, 7.9% of the women and 7.8% of the men had an autoimmune disease diagnosed before or during reproductive years.

The findings highlighted that many immune-mediated diseases had little impact on the number of children. However, women with selected immune-mediated diseases experience a higher prevalence of childlessness, with the top three diseases being Addison’s disease (23.9% more childlessness), juvenile idiopathic arthritis (9.3%), and vitamin B12 deficiency anaemia (8.6%). Several of the rheumatic diseases—particularly systemic lupus erythematosus and juvenile idiopathic arthritis—lead to higher rates of childlessness and fewer children.

The risks for pre-eclampsia, low birth weight, preterm delivery, non-elective C-sections and need of neonatal intensive care were increased for many conditions. Systemic lupus erythematosus and type 1 diabetes showed over two-fold risks for some of these outcomes. However, the risk of gestational diabetes was not higher for patients with any of the rheumatic diseases compared to the population.

“Despite seeing an elevated risk for diverse childbearing problems in rheumatic and other immune-mediated diseases, many of the complications are still fairly rare,” said Anne Kerola, the lead author of the study. “Family planning should actively be discussed between patients, both men and women, with rheumatic diseases and their healthcare providers. Pregnancies in women with rheumatic diseases are carefully followed up to tailor medications appropriately, which helps reduce risks.”

Reference: Anne M Kerola, Antti Palomäki, Hannele Laivuori, Tarja Laitinen, Martti Färkkilä, Kari K Eklund, Samuli Ripatti, Markus Perola, Andrea Ganna, Joni V Lindbohm, Nina Mars; Patterns of reproductive health in inflammatory rheumatic diseases and other immune-mediated diseases: a nationwide registry study; Journal: Rheumatology; DOI: 10.1093/rheumatology/keae122

Time-restricted eating may be tied to higher cardiovascular death risk, finds study

According to a study presented at the American Heart Association’s Epidemiology and Prevention; Lifestyle and Cardiometabolic Scientific Sessions 2024, people who limited their eating across less than 8 hours per day, a time-restricted eating plan, were more likely to die from cardiovascular disease compared to people who ate across 12-16 hours per day.

Time-restricted eating, a type of intermittent fasting, involves limiting the hours for eating to a specific number of hours each day, which may range from a 4- to 12-hour time window in 24 hours. Many people who follow a time-restricted eating diet follow a 16:8 eating schedule, where they eat all their foods in an 8-hour window and fast for the remaining 16 hours each day. Previous research has found that time-restricted eating improves several cardiometabolic health measures, such as blood pressure, blood glucose and cholesterol levels.

“Restricting daily eating time to a short period, such as 8 hours per day, has gained popularity in recent years as a way to lose weight and improve heart health. However, the long-term health effects of time-restricted eating, including the risk of death from any cause or cardiovascular disease, are unknown,” said senior study author Victor Wenze Zhong, Ph.D., a professor and chair of the department of epidemiology and biostatistics at the Shanghai Jiao Tong University School of Medicine in Shanghai, China.

In this study, researchers investigated the potential long-term health impact of following an 8-hour time-restricted eating plan. They reviewed information about dietary patterns for participants in the annual 2003-2018 National Health and Nutrition Examination Surveys (NHANES) in comparison to data about people who died from 2003 through December 2019, from the Centers for Disease Control and Prevention’s National Death Index database.

The analysis revealed the following:

1.People who followed a pattern of eating all of their food across less than 8 hours per day had a 91% higher risk of death due to cardiovascular disease.

2.The increased risk of cardiovascular death was also seen in people living with heart disease or cancer.

3.Among people with existing cardiovascular disease, an eating duration of no less than 8 but less than 10 hours per day was also associated with a 66% higher risk of death from heart disease or stroke.

4.Time-restricted eating did not reduce the overall risk of death from any cause.

5.An eating duration of more than 16 hours per day was associated with a lower risk of cancer mortality among people with cancer.

“We were surprised to find that people who followed an 8-hour, time-restricted eating schedule were more likely to die from cardiovascular disease. Even though this type of diet has been popular due to its potential short-term benefits, our research clearly shows that, compared with a typical eating time range of 12-16 hours per day, a shorter eating duration was not associated with living longer,” said Zhong.

Reference: The American Heart Association: AHA EPI|Lifestyle Scientific Sessions 2024