# Lesson 8 — Health Behaviors, Mental Health, and Social Influence (v3 expanded)

*Companion-podcast transcript • Sarah & Kiffer*  
*~4885 words • ~26.5 min audio*

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**Sarah:** Welcome back to Office Hours. I'm Sarah.

**Kiffer:** And I'm Kiffer. Today is Lesson 8, Health Behaviors, Mental Health, and Social Influence. And I want to open with the claim the lesson hinges on, which is that almost every modern public health move on a behavior — taxation, marketing restrictions, plain packaging, point-of-sale rules, age limits, smoke-free environments — was developed first on tobacco. If you understand the tobacco story, you understand the basic playbook of modern behavioral public health.

**Sarah:** And then we extend the playbook into other behaviors and into the mental health and addiction landscape and into social influence.

**Kiffer:** Right. Tobacco is the founding case, but the lesson then walks into the behavioral theories, addiction reconceptualized as chronic disease, the deinstitutionalization of psychiatric care, and the social-network and loneliness research that has reshaped how we think about what counts as a health exposure.

**Sarah:** Let's start with Doll and Hill.

**Kiffer:** In 1950, Richard Doll and Austin Bradford Hill published a case-control study in the British Medical Journal. They interviewed seven hundred and nine lung cancer patients and seven hundred and nine hospital controls across twenty London hospitals. Findings: ninety-nine point seven percent of lung cancer cases were smokers, compared with ninety-five percent of controls. The relationship was clearly dose-responsive, with heavier smokers having higher cancer rates.

**Sarah:** And the case-control design was still being worked out.

**Kiffer:** It was a relatively new design at the time. So Doll and Hill followed up with the British Doctors Study, launched in 1951. Prospective cohort, thirty-four thousand four hundred and thirty-nine male British doctors followed for the rest of their lives. By 1956 the dose-response between smoking and lung cancer was established with extraordinary clarity. The fifty-year follow-up paper, published in the B M J in 2004, is one of the most-cited epidemiological papers ever. Lifelong smokers lost approximately ten years of life expectancy compared with non-smokers.

**Sarah:** And then in 1965, Bradford Hill gives the address that produces the viewpoints.

**Kiffer:** Royal Society of Medicine, 1965. Hill articulated nine 'aspects' or 'viewpoints' for evaluating causation in observational data — strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experimental evidence, analogy. He was explicit that they were viewpoints to consider, not a checklist. The framework remains foundational. You'll meet it again in H S C I three-forty-one.

**Sarah:** Pivotal political event is the 1964 Surgeon General's Report.

**Kiffer:** Luther Terry, U S Surgeon General, convened an expert advisory committee in 1962 to review the evidence. Doll, Hill, Hammond, and other epidemiologists served on it. The 1964 report concluded that cigarette smoking was causally related to lung cancer in men. It was released on a Saturday morning, January eleventh 1964, to minimize stock market disruption, which it did — tobacco stocks declined modestly but didn't crash.

**Sarah:** And the report triggers a fifty-year sequence of regulation.

**Kiffer:** Warning labels on packages in 1965 in the U S and 1972 in Canada. Broadcast advertising bans in 1971 in the U S and 1972 in Canada. Workplace and indoor smoking restrictions through the eighties and nineties. Excise tax increases, continuous. Point-of-sale display restrictions in most Canadian provinces by 2010. Plain packaging, Australia in 2012, Canada in 2019. Each step was contested. Each was opposed by tobacco companies. And each produced measurable population-level effects.

**Sarah:** The cumulative numbers in Canada are striking.

**Kiffer:** Adult smoking prevalence in Canada has fallen from approximately fifty percent in the 1960s to approximately ten percent in the 2020s. One of the largest behavioral changes in public health history. And it was a combination of supply-side regulation, demand-side education, tax-driven price increases, and structural changes to where smoking is permitted. None of those alone would have done it. The combination did.

**Sarah:** The Master Settlement Agreement in 1998 is worth pausing on.

**Kiffer:** M S A. November 1998. Forty-six U S state attorneys general and the four largest tobacco companies. The companies agreed to pay two hundred and six billion dollars over twenty-five years and accept marketing restrictions, particularly marketing to youth, in exchange for legal immunity from future state lawsuits. And the discovery materials from those lawsuits — millions of internal documents — were released. They document that tobacco companies had known of the addiction and disease risks since at least the 1950s and had deliberately concealed and contested that knowledge.

**Sarah:** Those documents now live in the Truth Tobacco Industry Documents archive.

**Kiffer:** Right. And they've become foundational evidence for how regulated industries respond to evidence of harm. The pattern is recognizable now: fund counter-research, dispute the evidence, attack the researchers, claim consumer choice is the proper frame, target youth as future customers. Subsequent industries — sugar, opioids, fossil fuels and climate, ultra-processed food — have followed the same template. The tobacco playbook is both a public health success and a template for understanding how industries respond when the science threatens their market.

**Sarah:** Plain packaging is the most recent major addition.

**Kiffer:** Plain packaging requires standardized packaging, no brand logos, product name in a standardized font, prominent graphic health warnings. Australia introduced it in December 2012. Upheld in domestic and international litigation. U K followed in 2017, France in 2017, Canada in 2019. About twenty countries now have it. The quasi-experimental evidence is good — Australian smoking prevalence declined more rapidly after plain packaging than before. The mechanism is partly reducing product appeal, especially to young people who are sensitive to brand imagery, and partly increasing prominence of health warnings.

**Sarah:** And the contemporary frontier is vaping.

**Kiffer:** E-cigarettes emerged in the late 2000s, initially marketed as cessation aids and reduced-harm alternatives. The product appeals strongly to young people and has driven substantial increases in youth nicotine initiation in countries with relaxed regulation. The 2019 E V A L I outbreak — vaping-associated lung injury, predominantly linked to vitamin E acetate in illicit T H C products — complicated the picture further. The federal Tobacco and Vaping Products Act in Canada provides the basic framework but provinces vary substantially in their specific restrictions.

**Sarah:** Let's move to the behavioral theories the lesson surveys. You don't need to memorize them, but you should recognize them.

**Kiffer:** There are four major ones the lesson covers. The Health Belief Model, developed by Hochbaum and Rosenstock and others at the U S Public Health Service in the 1950s and 1960s, proposes that people engage in a health behavior when they perceive susceptibility, severity, benefits, low barriers, and receive a cue to action. Originally developed to explain why people weren't showing up for T B screening.

**Sarah:** Theory of Planned Behavior.

**Kiffer:** Icek Ajzen, 1980s. The immediate determinant of behavior is intention, and intention is determined by three factors — attitudes toward the behavior, subjective norms about what important others think, and perceived behavioral control. One of the most-tested behavioral theories. The limit is that it treats behavior as primarily intentional, which often underweights habit, emotion, and environmental constraint.

**Sarah:** Transtheoretical or Stages of Change.

**Kiffer:** Prochaska and DiClemente, early 1980s, originally developed for smoking cessation. Five stages: precontemplation, contemplation, preparation, action, maintenance. Very influential in clinical practice — addictions counseling, motivational interviewing. Limit is that subsequent empirical work has found the stages are often less discrete than the model implies, and stage-matched interventions don't reliably outperform untargeted ones.

**Sarah:** Social Cognitive Theory.

**Kiffer:** Albert Bandura, primarily through the 1970s and 1980s. Reciprocal interactions between person, behavior, and environment, with particular attention to self-efficacy — the belief in one's capability to perform a specific behavior. Self-efficacy is one of the most-cited constructs in all of psychology. Limit, like the others, is that it treats individual cognition as primary even when structural factors dominate.

**Sarah:** And then there's the broader honest critique that the lesson makes.

**Kiffer:** Theory-based interventions outperform untheorized interventions, and that's a real finding. But the effect sizes are modest. A theory-based smoking cessation intervention might produce a five percentage point absolute increase in quit rates at twelve months relative to no treatment. Meaningful, replicable, worth doing. Not transformative. The structural interventions on tobacco — taxation, marketing restrictions, smoke-free environments — produced larger population effects than the individual interventions, though both contributed.

**Sarah:** The nudge approach is the more recent complement.

**Kiffer:** Behavioral economics. Daniel Kahneman, Amos Tversky, Richard Thaler. Thaler and Cass Sunstein's 2008 Nudge book popularized the application to policy. Nudges modify the choice environment to make healthier choices easier without restricting choice. Default enrollment in organ donor registries. Pre-selected smaller portion sizes. Healthier foods at eye level. Default opt-out for retirement savings. Each is small, often cheap, and has measurable effects. The critics argue that nudges can substitute for structural intervention; the defenders argue they work and don't preclude it. The honest answer is somewhere between — they're real tools with modest evidence of effectiveness, and they shouldn't be confused with structural change.

**Sarah:** Okay, let's transition to mental health and addiction. The lesson makes some strong claims about how society's conceptualization of these things determines how it responds.

**Kiffer:** Through most of the twentieth century, addiction was understood as a moral failing — lack of willpower deserving punishment rather than treatment. The disease model emerged over decades. American Medical Association declared alcoholism a disease in 1956. The Big Book of Alcoholics Anonymous, first published in 1939, framed it as a disease requiring lifelong management. Neuroscience research from the 1970s onward — Nora Volkow at the N I D A is the major contemporary figure — characterized addiction as involving specific neural circuits and persistent neuroadaptations. That gave biological foundation to the disease framing.

**Sarah:** And the disease model opens the door to medical treatment and harm reduction.

**Kiffer:** Methadone for opioid dependence from 1964. Naltrexone for alcohol from 1995. Buprenorphine from 2002. Varenicline for tobacco from 2006. Needle exchange from the 1980s. Supervised consumption sites from 2003 in Canada. And a different criminal justice approach — drug courts, treatment alternatives to incarceration. The shift is incomplete: many people with addictions still encounter primarily criminal-justice responses rather than treatment responses, and the disease-model rhetoric has not always been backed by treatment-system capacity.

**Sarah:** Canada's pioneering site is InSite.

**Kiffer:** Insite, Vancouver Downtown Eastside, opened September 2003. North America's first sanctioned supervised consumption site. The federal Conservative government tried to close it in the late 2000s. The Supreme Court of Canada's 2011 decision in P H S Community Services Society v Canada ruled that closing Insite would violate the Charter rights of users. After that ruling, dozens of additional supervised consumption sites have opened across Canadian cities. The evidence base — overdose prevention, increased entry to treatment, reduced public injection, no increase in nearby drug use — is now substantial.

**Sarah:** And the contemporary crisis is the opioid epidemic.

**Kiffer:** The deadliest drug epidemic in modern history. Purdue Pharma introduced OxyContin — extended-release oxycodone — in 1996, with aggressive marketing to physicians on the false premise that the extended-release formulation made it non-addictive. Internal documents released through litigation document that Purdue knew of the addictive potential and marketed deceptively. Prescription opioid use rose dramatically through the 2000s. Heroin use rose in the 2010s as prescription supplies were restricted. Illicit fentanyl entered the supply chain from around 2014 onward.

**Sarah:** And the death toll.

**Kiffer:** Annual North American opioid deaths exceeded one hundred thousand in the U S by 2021. Approximately eight thousand per year in Canada by 2023. British Columbia declared a public health emergency in April 2016 over the toxic drug crisis. The emergency remains in effect. And the deaths are concentrated demographically — Indigenous people, low-income people, people experiencing homelessness, people with co-occurring mental illness are heavily overrepresented.

**Sarah:** The response combines several components.

**Kiffer:** Harm reduction — supervised sites, take-home naloxone, drug checking, safer supply pilots. Expanding but contested. Treatment expansion — opioid agonist therapy access, integration with primary care. Expanding but inadequate to demand. Pain management reform — prescribing guidelines, prescription monitoring. Has reduced new initiation but with mixed effects on existing patients. Litigation and accountability — Purdue's 2020 settlement, Sackler family settlements. Substantial financial penalties but not full accountability. And decriminalization of personal use — B C's pilot, 2023 to 2024, partly rolled back in 2024. That's one of the most consequential drug policy experiments of the decade and is being intensely studied.

**Sarah:** Deinstitutionalization is the other big piece of the mental health story.

**Kiffer:** From the 1950s through the 1980s, North American psychiatric hospitals systematically closed. The Ontario psychiatric hospital population fell from approximately nineteen thousand in 1960 to fewer than four thousand by 1990. Similar trajectories across Canadian provinces and U S states. The driving logic combined humanitarian concern about institutional conditions, civil rights principles about community living, new antipsychotic medications that made community treatment possible, and the anti-psychiatry movement and Goffman's Asylums.

**Sarah:** The execution was incomplete.

**Kiffer:** Community mental health services were funded inadequately to meet the needs of patients leaving institutions. Large populations of people with serious mental illness ended up in jails — the L A County Jail and Cook County Jail in Chicago are now the largest psychiatric facilities in the U S. Or in homeless shelters and on streets. Or cycling through emergency rooms without continuity of care. The Vancouver Downtown Eastside, the Chicago South Side, analogous urban concentrations of marginalized populations were partly produced by deinstitutionalization without adequate community support. The lesson generalizes: a good policy direction without the resources to make it work can produce worse outcomes than the system it replaced.

**Sarah:** Stigma reduction is one of the bright spots over the past thirty years.

**Kiffer:** Public attitudes toward mental illness have shifted substantially, particularly toward depression and anxiety. Stigma toward serious mental illness — schizophrenia, bipolar disorder, personality disorders — and toward substance use disorders has been more resistant to change. The Bell Let's Talk campaign in Canada, launched in 2010, is a high-visibility example. Its measurable effect on professional treatment-seeking is debated, but it has clearly shifted vocabulary and visibility in public conversation. And there's a generation now in their teens and twenties who discuss mental health far more openly than previous generations did.

**Sarah:** And the clinical landscape has changed.

**Kiffer:** S S R Is from Prozac in 1987 onwards made depression treatment more accessible and more tolerable than the older tricyclics. Second-generation antipsychotics, A D H D medications, structured psychotherapies — cognitive-behavioral therapy, dialectical behavior therapy, acceptance and commitment therapy. Online platforms — BetterHelp, Talkspace, Inkblot, provincial public-system platforms — have expanded access. Despite all that, mental health remains underserved relative to its population health impact. Depression and anxiety are now leading causes of disability-adjusted life years globally. Wait times for publicly-funded psychiatric assessment in many Canadian provinces exceed six to twelve months. Children's mental health services are particularly inadequate.

**Sarah:** Let's turn to the social-influence piece, because the lesson argues the most consequential behavioral findings of the past twenty years are arguably not about diet or exercise or smoking. They're about who we know and how we relate.

**Kiffer:** Christakis and Fowler. Beginning in 2007, Nicholas Christakis at Harvard, now at Yale, and James Fowler at U C San Diego, published a series of papers using Framingham Heart Study social network data. Obesity in the New England Journal of Medicine in 2007. Smoking cessation, also in N E J M, in 2008. Happiness in B M J in 2008. The claim: behaviors and states appeared to cluster in networks beyond what chance would predict, with effects detectable up to three degrees of separation. Your friend's friend's friend's behavior is associated with your own.

**Sarah:** And the methodology has been heavily contested.

**Kiffer:** Several technical critiques. Confounding by shared environment — people who live near each other share characteristics other than their direct social tie. Homophily — people choose friends with similar characteristics, so you get apparent spread when really the similarity was there before the friendship. And specific statistical issues. Cosma Shalizi, Andrew Thomas, and others showed that the original effect sizes were probably overstated. The general lesson is that social ties matter for health, but characterizing how they matter is methodologically harder than the early enthusiasm suggested.

**Sarah:** Loneliness as a public health concern.

**Kiffer:** May 2017, then-U S Surgeon General Vivek Murthy declared loneliness an epidemic in a Harvard Business Review article and subsequent advocacy. His central empirical claim was that social isolation was associated with mortality risk comparable to smoking fifteen cigarettes per day. That came from meta-analyses by Julianne Holt-Lunstad and colleagues at Brigham Young — social isolation, loneliness, and living alone each predict increased mortality with effect sizes comparable to many established risk factors. Murthy's 2023 advisory expanded the case.

**Sarah:** And the framing has been adopted internationally.

**Kiffer:** U K appointed a Minister for Loneliness in 2018. Japan in 2021. W H O has published policy briefs on social connection as a determinant of health. Beyond mortality, social isolation is associated with cardiovascular disease, cognitive decline, depression, immune function. The biological mechanisms include chronic activation of stress response systems, inflammation, and possibly direct effects on cardiovascular and metabolic regulation. C O V I D, with its enforced isolation, was a kind of natural experiment that documented effects in older adults particularly.

**Sarah:** But the intervention question is harder than the case-making question.

**Kiffer:** Right. Public health doesn't have a well-developed toolkit for addressing loneliness at population scale. Individual interventions — befriending programs, support groups, social prescribing — have modest effects but limited reach. Structural interventions — built environment, third places, transit, retirement-system design, digital information environment — have larger potential effects but cross multiple sectoral boundaries. No single agency owns the levers. Loneliness in 2026 is partly individual experience and largely produced by structural conditions.

**Sarah:** Stigma is the other thread the lesson closes on.

**Kiffer:** Erving Goffman's 1963 book Stigma: Notes on the Management of Spoiled Identity introduced the contemporary framing. Public health research has documented stigma effects on mental health treatment-seeking, H I V testing and treatment uptake, addiction treatment access, obesity-related medical care, and many other domains. The mechanism is multifaceted. Anticipated stigma reduces engagement with healthcare. Experienced stigma in healthcare encounters produces avoidance. Stigmatized conditions receive less research funding and clinical training. Internalized stigma reduces self-efficacy and help-seeking. And stigma erodes social networks.

**Sarah:** Anti-stigma interventions have been evaluated.

**Kiffer:** Mixed results. Some campaigns — Bell Let's Talk in Canada, Time to Change in the U K — have produced measurable reductions in stigmatizing attitudes. Whether the attitude changes translate into more help-seeking and better outcomes is more contested. The general lesson, similar to the rest of the lesson, is that individual-level attitude change matters and produces modest effects, while structural change — anti-discrimination legislation, parity of mental and physical health coverage, integration of substance use treatment into mainstream healthcare — produces larger effects.

**Sarah:** Let's bring this together. Takeaways.

**Kiffer:** Walk me through them.

**Sarah:** First takeaway. Tobacco is the founding case of modern behavioral public health. Doll and Hill in 1950, the British Doctors Study from 1951, the 1964 Surgeon General's Report, the fifty-year sequence of regulation. Smoking prevalence in Canada from fifty percent in the 1960s to ten percent in the 2020s. The playbook — taxation, marketing restrictions, plain packaging, smoke-free environments — works at population scale, on long timelines, and is the model for every subsequent behavioral target.

**Kiffer:** Second takeaway. The four major behavioral theories — Health Belief Model, Theory of Planned Behavior, Stages of Change, and Social Cognitive Theory — are worth recognizing rather than memorizing. Theory-based interventions outperform untheorized ones, but the effect sizes are modest. Individual-level behavior change works for what it can do; structural intervention does the heavy lifting at population scale.

**Sarah:** Third takeaway. Addiction has been reframed from moral failing to chronic disease, opening the door to medical treatment, harm reduction, and a different criminal justice approach. Insite, the Supreme Court's 2011 ruling, the expansion of supervised consumption sites — these are public health institutional achievements. The opioid crisis is the deadliest drug epidemic in modern history and is concentrated in already-marginalized populations.

**Kiffer:** Fourth takeaway. Deinstitutionalization of psychiatric care was the right policy direction executed with inadequate community support, and we are still living with the consequences — populations of people with serious mental illness in jails, shelters, on streets, and cycling through E Rs. Mental health remains underserved relative to its population health impact, with Canadian wait times often exceeding six to twelve months.

**Sarah:** Fifth takeaway. The Christakis-Fowler social-network research was overstated but pointed at something real. Social ties matter for health. Specific quantitative claims are methodologically harder to establish than the early enthusiasm suggested. The general framing — that behaviors and states cluster through networks and that social ties are health-relevant exposures — has reshaped how public health thinks about behavior.

**Kiffer:** Sixth takeaway. Loneliness has been framed as a public health epidemic. The case-making is increasingly settled — social isolation is a measurable mortality risk factor with biological mechanisms. The intervention question is unsettled. Structural conditions that produce loneliness — work hours, commutes, housing, transit, retirement, digital environment — are mostly outside the conventional health policy domain.

**Sarah:** Seventh takeaway. Stigma is a measurable health exposure with structural, institutional, internalized, and social mechanisms. Anti-stigma interventions produce modest attitude effects; structural change produces larger outcome effects. Every domain of public health — mental illness, addiction, H I V, obesity, disability, racialized identity — has a stigma dimension that affects outcomes.

**Kiffer:** Eighth, and I want to give the synthesizing line. The recurring lesson of this whole lesson is that individual behavior change works for what it can do, and structural intervention does the heavy lifting at population scale. The tobacco story is the cleanest example. The opioid response, the mental health rebuild, the loneliness policy frontier — all of them require structural change to produce population-level effects. Individual-level work is necessary and useful for targeted contexts; it is rarely sufficient at population scale.

**Sarah:** Before we move on from tobacco, I want to flag the methodological piece. Hill's viewpoints emerged from this case.

**Kiffer:** Right. Strength of association, consistency across studies, specificity of effect, temporality, biological gradient — dose-response — plausibility, coherence with established knowledge, experimental evidence when available, and analogy. Hill was explicit that these were viewpoints to consider, not a checklist. And modern causal inference has elaborated the framework. Directed acyclic graphs from Judea Pearl and colleagues formalize which variables to adjust for and which to leave alone. Target trial emulation asks researchers to design observational analyses as if they were emulating a hypothetical R C T. You'll meet all of this in H S C I three-forty-one and four-ten.

**Sarah:** One thing I want to highlight is the documents from the M S A discovery.

**Kiffer:** The Truth Tobacco Industry Documents archive is publicly searchable, and it's foundational evidence for how industries respond to threats. The patterns are now well-characterized: fund counter-research to manufacture doubt, dispute the epidemiological evidence on methodological grounds, attack individual researchers, claim consumer choice is the proper framing rather than public health, target youth as future customers. The sugar industry funded research in the sixties and seventies that downplayed sugar's role in cardiovascular disease and emphasized fat. The fossil fuel industry funded climate denial through the eighties and nineties. The ultra-processed food industry funded research that downplayed processing and emphasized individual choice. The opioid industry, through Purdue, did all of the above. Recognizing the playbook when you see it is one of the things this course is trying to teach.

**Sarah:** And it's worth being clear-eyed about what individual behavior change can and can't do. Picking up on the structural-versus-individual tension.

**Kiffer:** The honest assessment is that individual smoking cessation works for about five to fifteen percent of smokers per year, depending on the intervention intensity. Population-level decline driven only by individual cessation would have taken many decades longer than what actually happened. Most of the population decline is attributable to structural changes — taxes, marketing restrictions, indoor smoking bans, plain packaging. The same is true for weight management, where individual interventions produce small population effects. The same is true for activity, diet, most behaviors. The structural-individual choice is rarely a forced choice. The optimal mix combines both. Structural carries the population load. Individual does targeted work in clinical contexts and for high-risk subpopulations.

**Sarah:** On the addiction piece, the safer supply pilots in B C are worth a word.

**Kiffer:** B C has been piloting safer supply — providing pharmaceutical-grade alternatives to the illicit toxic drug supply — for several years now. The evidence is mixed across outcomes and contested politically. It's one of the most consequential drug policy experiments of the decade, and it's being intensely studied. Decriminalization of personal use in B C from 2023 to 2024 was the other major experiment, partially reversed in 2024 to 2025. The reversal happened despite the evidence not changing fundamentally; it happened because political pressure built faster than the evidence base could grow. That's a useful lesson about how evidence-based policy actually operates.

**Sarah:** And on social media specifically as a contemporary loneliness driver — Haidt's book.

**Kiffer:** Jonathan Haidt's The Anxious Generation, 2024. Strongest version of the case that social media is causally implicated in adolescent mental health declines since 2012. The empirical case has been contested by other researchers — Andrew Przybylski and others have argued the effects are smaller and less specific than Haidt claims. The policy response is proceeding rapidly anyway. School phone bans, age restrictions, content regulation. Several Canadian jurisdictions have moved on this. The evidence on intervention effectiveness will follow over the next few years. It's another example of how policy and evidence interact in real time, often with policy moving faster than the evidence can keep up with.

**Sarah:** Quick callback to earlier lessons. We had Lesson 4 on nutrition and activity, where the same pattern showed up — Mexico's sugar tax, Chile's front-of-pack warnings.

**Kiffer:** Yeah. And the same will likely be true for ultra-processed food, for emerging nicotine products, for whatever the next behavioral target is. The general lesson — durable population-scale behavior change requires structural intervention sustained over decades — is the lesson that recurs across most domains the course covers.

**Sarah:** I want to ask you about moral injury too, because the lesson mentions it and it's increasingly used in healthcare worker contexts.

**Kiffer:** Moral injury was originally described by Jonathan Shay in 1994 in combat veterans — the psychological wound of being forced to participate in actions that violate one's deeply held values. The framing has been extended to healthcare workers during C O V I D, who reported being required to deliver care they considered below the standard of acceptable practice. Rationing equipment, deferring care for non-C O V I D conditions, witnessing preventable deaths due to system failures. Moral injury captures something burnout doesn't — not just emotional exhaustion, but ongoing psychological harm from being asked to compromise on values. The clinical and organizational response to both is still developing. Individual wellness programs and resilience training have modest effects and have been substantially critiqued as offloading systemic problems onto workers. Structural interventions — adequate staffing, manageable workloads, clinician participation in decision-making — have stronger evidence but are harder politically and economically. We'll come back to this in Lesson 10 when we cover occupational health.

**Sarah:** And the post-C O V I D mental health picture is still being processed.

**Kiffer:** Survey data across Canadian, U S, and European healthcare workforces showed burnout prevalence increasing from about thirty to forty percent pre-pandemic to about fifty to sixty percent during and after the peak. Healthcare worker departures, early retirements, shifts to lower-intensity practice followed. Primary care, emergency medicine, critical care, and nursing across Canadian jurisdictions are facing substantial staffing challenges that have been predicted but inadequately addressed. The general population mental health picture is also still recovering — anxiety, depression, substance use, eating disorders all elevated. The recovery is uneven, with younger adults and parents of young children showing particularly persistent effects.

**Sarah:** And one more piece I want to ask about — the role of Larry Kramer and ACT UP, who get a nod in the figures introduced for this lesson.

**Kiffer:** Yeah. We touched on Larry Kramer in Lesson 5 around H I V activism, but he's relevant here too because of how patient-activist organizing reshaped the research enterprise itself. ACT UP in the late 1980s and early 1990s forced changes in F D A drug approval, in clinical trial design — what is now called patient-oriented research has roots in that activism. The framing 'nothing about us without us' that comes out of disability rights, which we'll cover in the final lesson, has the same spirit. The general lesson is that public health and biomedical research were historically done to populations rather than with them, and the contemporary push to do research with affected communities has substantially changed how the field operates.

**Sarah:** And that has implications for behavioral interventions too. Who designs them, who is in the room when they're designed, what they take seriously as outcomes.

**Kiffer:** Right. Behavioral interventions designed without the affected population in the room tend to assume the problem is information or motivation, when often the problem is structural — time, money, access, safety. The best contemporary behavioral interventions are co-designed with the target community and combine individual support with structural change. We'll see this again in Lesson 11 when we get to social determinants and Indigenous health, where Indigenous-led research has been part of the move toward more honest and useful intervention design.

**Sarah:** Next lesson, environmental health. Air, indoor environments, the built environment, climate.

**Kiffer:** And we'll see structural intervention from a different angle — the engineering and regulation that have delivered most of public health's largest gains. See you then.

**Sarah:** Take care, everyone.