Caffeine Citrate

Coffee can help you stay awake. But what does caffeine actually do to your brain once you're asleep? Using AI, a team of researchers has an answer: it affects the brain's 'criticality'. Caffeine is not only found in coffee, but also in tea, chocolate, energy drinks and many soft drinks, making it one of the most widely consumed psychoactive substances in the world. In a study published in April in Nature Communications Biology, a team of researchers from Université de Montréal shed new light on how caffeine can modify sleep and influence the brain's recovery -- both physical and cognitive -- overnight. The research was led by Philipp Thölke, a research trainee at UdeM's Cognitive and Computational Neuroscience Laboratory (CoCo Lab), and co-led by the lab's director Karim Jerbi, a psychology professor and researcher at Mila -- Quebec AI Institute. Working with with sleep-and-aging psychology professor Julie Carrier and her team at UdeM's Centre for Advanced Research in Sleep Medicine, the scientists used AI and electroencephalography (EEG) to study caffeine's effect on sleep. They showed for the first time that caffeine increases the complexity of brain signals and enhances brain "criticality" during sleep. Interestingly, this was more pronounced in younger adults. "Criticality describes a state of the brain that is balanced between order and chaos," said Jerbi. "It's like an orchestra: too quiet and nothing happens, too chaotic and there's cacophony. Criticality is the happy medium where brain activity is both organized and flexible. In this state, the brain functions optimally: it can process information efficiently, adapt quickly, learn and make decisions with agility." Added Carrier: "Caffeine stimulates the brain and pushes it into a state of criticality, where it is more awake, alert and reactive While this is useful during the day for concentration, this state could interfere with rest at night: the brain would neither relax nor recover properly." 40 adults studied To study how caffeine affects the sleeping brain, Carrier's team recorded the nocturnal brain activity of 40 healthy adults using an electroencephalogram. They compared each participant's brain activity on two separate nights -- one when they consumed caffeine capsules three hours and then one hour before bedtime, and another when they took a placebo at the same times. "We used advanced statistical analysis and artificial intelligence to identify subtle changes in neuronal activity," said Thölke, the study's first author. "The results showed that caffeine increased the complexity of brain signals, reflecting more dynamic and less predictable neuronal activity, especially during the non-rapid eye movement (NREM) phase of sleep that's crucial for memory consolidation and cognitive recovery." The researchers also discovered striking changes in the brain's electrical rhythms during sleep: caffeine attenuated slower oscillations such as theta and alpha waves -- generally associated with deep, restorative sleep -- and stimulated beta wave activity, which is more common during wakefulness and mental engagement. "These changes suggest that even during sleep, the brain remains in a more activated, less restorative state under the influence of caffeine," says Jerbi, who also holds the Canada Research Chair in Computational Neuroscience and Cognitive Neuroimaging. "This change in the brain's rhythmic activity may help explain why caffeine affects the efficiency with which the brain recovers during the night, with potential consequences for memory processing." People in their 20s more affected The study also showed that the effects of caffeine on brain dynamics were significantly more pronounced in young adults between ages 20 and 27 compared to middle-aged participants aged 41 to 58, especially during REM sleep, the phase associated with dreaming. Young adults showed a greater response to caffeine, likely due to a higher density of adenosine receptors in their brains. Adenosine is a molecule that gradually accumulates in the brain throughout the day, causing a feeling of fatigue. "Adenosine receptors naturally decrease with age, reducing caffeine's ability to block them and improve brain complexity, which may partly explain the reduced effect of caffeine observed in middle-aged participants," Carrier said. And these age-related differences suggest that younger brains may be more susceptible to the stimulant effects of caffeine. Given caffeine's widespread use around the world, especially as a daily remedy for fatigue, the researchers stress the importance of understanding its complex effects on brain activity across different age groups and health conditions. They add that further research is needed to clarify how these neural changes affect cognitive health and daily functioning, and to potentially guide personalized recommendations for caffeine intake.

The activation of Protein Kinase A (PKA) is a critical part in how the body responds to stress and starvation. Using a variety of imaging and biochemical techniques, a team of researchers has revealed how the metabolic cycle that activates PKA resets itself between stressful events. Being cut off in traffic, giving a presentation or missing a meal can all trigger a suite of physiological changes that allows the body to react swiftly to stress or starvation. Critical to this "fight-or-flight" or stress response is a molecular cycle that results in the activation of Protein Kinase A (PKA), a protein involved in everything from metabolism to memory formation. Now, a study by researchers at Penn State has revealed how this cycle resets between stressful events so the body is prepared to take on new challenges. The details of this reset mechanism, uncovered through a combination of imaging, structural and biochemical techniques, was recently published in the Journal of the American Chemical Society. "Some of the early changes in the fight-or-flight response include the release of hormones, like adrenaline from stress or glucagon from starvation," said Ganesh Anand, associate professor of chemistry and of biochemistry and molecular biology in the Penn State Eberly College of Science and lead author of the paper. "These hormones trigger an important molecular cycle that ultimately activates PKA, a versatile protein that can regulate more than a hundred different target proteins inside the cell. Better understanding of this cycle has implications not only for stress and starvation, but for other things we put in our bodies, like caffeine and certain drugs that initiate or extend the cycle." In all cells of organisms from yeast to humans, PKA oscillates between active and inactive states. When hormones like glucagon or adrenaline bind to a specific location in the cell, they generate a molecule called cyclic AMP, or cAMP. This in turn binds to the inactive complex of proteins that contains PKA, switching the PKA to a more active state. But how exactly this cycle completes and the system resets itself has remained unclear. "You don't want this cycle to be perpetually on and responding once the stressful situation has passed," Anand said. "You want to be able to reset the system. Dysregulation of PKA due to errors in this reset process can lead to cardiovascular disease, metabolic syndromes and other disorders. We wanted to know how long this system could remain active and how you can shut it off." Using multiple imaging techniques -- including electron microscopy and the higher-resolution cryo-electron microscopy as well as biochemical techniques and several different forms of mass spectrometry, which provided insights into the dynamics of the complex -- the researchers uncovered at least three conformations of the complex that occur during the reset process that were previously unknown. They also clarified the physical space that these conformations use within the cell. "Molecules are not rigid rocks; they are constantly fluctuating, almost like they are breathing," Anand said. "Cryo-electron microscopy is a powerful imaging technique that has gained a lot of traction, but it ultimately gives you a static image. If you look at a photograph of a leg, you can guess at how the knee and the ankle work, but it's just a guess. We used a variety of other techniques to really understand the mobile 'joints' of this complex. It's an iterative approach; we moved back and forth between the different techniques as we uncovered new insights so that we could really understand what the different components are doing during a variety of conformational changes." Integral to the reset mechanism are phosphodiesterase proteins, or PDE, which remove the cAMP from the PKA complex, rendering the complex inactive once again. As the cAMP is removed, it can accumulate within the cell, allowing the number of reset cycles to be tracked. "The system becomes more efficient as it goes through more cycles," said Varun Venkatakrishnan, graduate student in chemistry in the Penn State Eberly College of Science and first author of the paper. "Just like a runner can build up stamina with practice, there is some capacity for building endurance with this fight-or-flight response. This system has a built-in timer, which can record how many laps it has run. We would like to better understand the implications of activating the cycle many times in a row. It's also possible we could trick the system into thinking it has run more laps than it has by adding cAMP." The researchers said that allowing the system to reset between stressors is physiologically important. For example, cAMP encourages memory formation, allowing memories to be formed around stressful events. Long-term stress can also increase the risk of developing Type 2 diabetes and impact the functioning of a variety of systems. "In the modern world, we are continuously getting stimulated, including by substances like caffeine and drugs, and we'd like to better understand what happens when the cycle is activated for a long time," Anand said. "Caffeine is a PDE inhibitor, so it essentially pauses the reset mechanism, and we end up getting the buzz from the stress response without the actual stress. And some drugs called glucagon-like-peptides or GLPs, such as those used to alter appetite and so called 'anti-obesity' drugs, can modulate the PKA cycle. If we can find a way to keep the reset for longer, we might be able to find a way to counteract some effects of stress." Additionally, the researchers said that the integrative, procedural framework of using cryo-electron microscopy, mass spectrometry and biochemical techniques could be adapted to understand the moving parts of a wide variety of protein complexes. In addition to Anand and Venkatakrishnan, the research team at Penn State includes Tatiana Laremore, associate research professor and director of the Proteomics and Mass Spectrometry Core Facility; Theresa Buckley, graduate student in chemistry; and Jean-Paul Armache, assistant professor of biochemistry and molecular biology. Data for this paper was collected using the Proteomics and Mass Spectrometry Core Facility and the Cryo-Electron Microscopy Core Facility within the Penn State Huck Institutes of the Life Sciences. Funding from Penn State supported this research.