#14 — At the Intersections — August 1, 2026

A person can carry a chronic viral infection for decades without a diagnosis. Tracking the pathways to such health outcomes is the focus of this issue of ComplexityPod. We begin with new universal screening guidelines for hepatitis B. This episode follows the paths that lead to certain health outcomes, from their origins all the way to their expression. Right, and we're starting with schizophrenia—how something like life experience can combine with a person's genetic risk to shape the condition. And then from there, drilling down into how that appears in the brain's own signaling. So you have these two different potential starting points. A study with Lena Palaniyappan looked at this, at how childhood trauma and what's called polygenic risk can have divergent effects. And those different effects show up in cognitive function and in the activity of subcortical brain structures. But there’s a related study that looks even more closely at the brain signals themselves, specifically what happens with thought disorder. Which is based on the idea that disorganized thought comes from a disruption in the brain's predictive processing, right? The system isn't anticipating correctly. Exactly. And beta oscillations, a type of brainwave, are thought to be part of that top-down predictive signaling. But this research didn't just look at the overall power of these waves. It focused on their transient 'burst' dynamics. So not a constant hum, but short, powerful periods of activity. What's the function of those bursts? They seem to help stabilize and reinstate the brain's internal models, especially in the default mode network. So researchers used magnetoencephalography, or MEG, to look at the resting-state brain activity in patients with schizophrenia and in a control group. And they were able to pull out these beta bursts from the data and measure them—their rate, duration, power, and how they synced up between different brain regions. Yes, and then they compared those brain activity measures with features of each person's speech, which is a way to gauge thought organization. And the results were specific: there was no difference in the conventional, overall beta power between the groups. But the burst dynamics told a different story. They did. Patients had shorter burst durations in one part of the default mode network. They also had increased synchrony of bursts within the left prefrontal cortex and between the two prefrontal cortices. And this connects back to the symptoms. You said they found a link to disorganized speech. That's the key finding. These specific patterns in the burst dynamics predicted how organized the patients' speech was. It suggests that an impaired coordination of this predictive beta signaling could be a mechanism that connects dysfunction in the brain's network to disorganized thought. So we've traced a path from the brain's internal signaling to a clinical symptom. Now let's widen the view to population health and the detection of chronic viral infections. A case study with Mia Biondi looks at screening for hepatitis B virus, or HBV. A 2025 Canadian guideline recommends that all adults get a one-time triple HBV serology test. For all adults, regardless of risk factors? That seems very broad. Why not just screen people who are at higher risk? Because risk-based screening has proven to be ineffective. Part of that is stigma around certain activities, but it's also because most people with HBV don't have any symptoms. And the prevalence numbers show why this is a concern. It's estimated to be under one percent in Canada’s general population, but for immigrants from countries where HBV is common, that estimate can be as high as five-point-six percent. And since routine HBV screening isn't part of the Canadian immigration medical exam, someone could live in the country for decades before getting a diagnosis. There's another complication, too, with partial screening. You mean for work, where they only test for immunity? Right. That isolated test can be misleading. An infected person doesn't typically produce the surface antibody that's being tested for, so they can be incorrectly told they're 'not immune' when they actually have an active infection. The case study describes exactly this: a man was told he wasn't immune, got a full course of the vaccine, but had never actually been screened for the virus itself. Which a triple serology test would have caught, because it gives a comprehensive picture of a person's status. So when a patient does get a new diagnosis of HBV, what's next? The guideline says to also screen for hepatitis D virus, or HDV. Coinfection with HDV accelerates the progression to advanced liver disease. And that coinfection can be quite common in some regions—up to 60 percent of cases in places like Mongolia, Romania, and parts of West and Central Africa. That's all for this issue. We'll be back next week with more research from the intersections of science. From ComplexityPod, thanks for listening.