It is Really True: Detailed Analysis Shows that Social Media Really do Lead to Silo Thinking

It is popular to claim that social media sites (SMSs), such as Twitter and Facebook, democratise knowledge. This is true in one sense – it places information within the easy reach of the population at large. Individuals certainly benefit.[1] But what about society at large? Here the story is bleak. Far from bringing people into contact with ideas that might challenge their precepts, SMSs increase intellectual isolation. Walter Quattrociocchi, writing in Scientific American,[2] summarises the mountain of data that has been painstakingly collated by himself and others; they analysed data from two million Facebook users in one study.[3] People eschew views they find challenging and isolate their attention in online groups, which reinforces their pre-existing beliefs. It gets worse – the less educated a person, the more isolationist they tend to be. Such people hew to conspiracy theories, which grow like a snowball among online communities. Scientific analysis is shut out so that detailed analysis of data on topics such as climate change are less widely disseminated. Conspiracy theories proliferate, for example, saying that climate change is a hoax perpetuated to further academic careers and earnings of alternative energy suppliers. The very worst news is that campaigns aimed at debunking these myths actually reinforce belief in conspiracy theories; there is no antidote to the myths perpetuated down social media.

SMSs are here to stay, but as the author says, the Information Revolution is fostering an Age of Credulity not an Age of Enlightenment.

— Richard Lilford, CLAHRC WM Director

References:

1. Lilford RJ. The Second Machine Age. NIHR CLAHRC West Midlands. 5 May 2017.
2. Quattrociocchi W. Why Social Media Became the Perfect Incubator for Hoaxes and Misinformation. Scientific American. April 2017.
3. Del Vicario M, Bessi A, Zollo F, et al. The Spreading of Misinformation Online. Proc Natl Acad Sci USA. 2016; 113(3): 554-9.

Providing Care at Less Cost – the Great Skill-mix Debate

Health care professionals do not all receive the same emoluments. In all countries doctors are paid the most. They carry the greatest responsibility for making decisions that affect people and they are the most likely to be sued – so their differential pay seems fair. But the other side of the coin is that non-doctor health professionals can do many things equally well, or perhaps better. Similarly, there are things that Community Health Workers can do as well or better than nurses, and again at lower unit cost. There are many types of skill mix initiative, and the most widely used classification emanated from Bonnie Sibbald,[1] herself a previous CLAHRC director:

Sibbald’s Skill-Mix Classification

Changing roles

• Extending roles
• Substituting – exchanging one type of worker for another
• Delegation
• Innovation – creating new jobs

Changing structures at the interface between services

• Transferring service from one setting to another
• Relocation
• Liaison

There are a number of systematic reviews on skill-mix summarising a great many articles. However, review authors agree that there is little clear evidence on effectiveness or cost-effectiveness. Many studies concentrate on skill substitution, usually comparing doctors and nurses.[2] However, the subject is hard to study, and deriving generalisable conclusions is always going to be difficult because of differences in context – especially training. One cadre that has received a lot of attention over the last two decades involves innovation more than substitution – the use of Community Health Workers. They have a valuable role in prevention (e.g. malnutrition/vaccination), maintenance of therapy (e.g. HIV, TB and hypertension), and frontline care (e.g. rehydration therapy), as discussed in previous News Blogs.[3-5]

— Richard Lilford, CLAHRC WM Director

References:

1. Sibbald B, Shen J, McBride A. Changing the skill-mix of the health care workforce. J Health Serv Res Policy. 2004; 9(s1):28-38.
2. Antunes V & Moreira JP. Skill mix in healthcare: An international update for the management debate. Int J Healthc Man. 2013; 6(1): 12-7.
3. Lilford RJ. Lay Community Health Workers. NIHR CLAHRC West Midlands News Blog. 10 April 2015.
4. Lilford RJ. An Intervention so Big You Can See it from Space. NIHR CLAHRC West Midlands News Blog. 4 December 2015.
5. Lilford RJ. Between Policy and Practice – the Importance of Health Service Research in Low- and Middle-Income Countries. NIHR CLAHRC West Midlands News Blog. 27 January 2017.

Government vs. Private Schools

CLAHRC WM is not just interested in health care since the methods we use are equally relevant to decision-makers in education, social services, industrial policy, criminology, and so on. We should all be learning from each other. In a previous blog I reported on the (mostly positive) results of the ‘Moving to Opportunity’ experiment in the USA, where families were given an opportunity to move from a deprived neighbourhood to a more salubrious one. So I was interested to spot an RCTs of vouchers that allowed children (over a wide age range) from government schools to attend private schools (also in the USA).[1] The experiment was recent (last five years) and we have outcomes at one year only. Seventy percent of pupils allocated a voucher to attend a private school took up their offer; so both intention to treat and per protocol analyses are reported. The educational outcomes were lower in the intervention group, and were statistically significantly lower for mathematics. This negative effect was greater if the voucher was taken up than if it was not. The negative effect was greater if the child came from a school that was not rated as poor performing than if the previous school was rated satisfactory or good. The negative effect was greatest if the child was in elementary school, and non-significantly positive if they were already in high school.

What caused the negative effect on educational outcomes? Simply moving school does not seem to explain the results, since a proportion of control children moved school with little or no apparent effect. However, private schools provide less instructional time than government schools, especially in elementary school. Other studies have also noted negative effects of moving children to private school on educational outcomes in the short term. But it is far too early to declare the intervention a failure. There is a limit to how much an elementary school child can assimilate, and it is the long-term effects that are important. However, I was surprised by this result – educational interventions have a habit of producing results different to those intended. Full marks to the US Congress, which had the wisdom to evaluate its own policies. The UK Cabinet Office has published a document arguing for more RCTs of policy,[2] and I expect to be able to report the results of further RCTs of educational interventions in the News Blog.

— Richard Lilford, CLAHRC WM Director

References:

1. Dynarski M, Rui N, Webber A, Gutmann B, Bachman M. Evaluation of the DC Opportunity Scholarship Program. Impacts After One Year. Alexandria, VA: Institute of Education Sciences, 2017.
2. Haynes L, Service O, Goldacre B, Torgerson D. Test, Learn, Adapt: Developing Public Policy with Randomised Controlled Trials. London: UK Cabinet Office, 2012.

Bariatric Surgery – Improve Five-Year Outcomes

The short-term (2-3 year) outcomes of bariatric surgery have been extensively studied in RCTs, and the (mainly) positive outcomes documented. Now we can use unbiased information to look a little further into the future as longer-term outcomes of an RCT of bariatric surgery have been published.[1] Outcomes were assessed at the age of five years among 150 overweight, type 2 diabetic people randomised to intensive medical therapy alone versus such therapy accompanied by bariatric surgery (by-pass or gastric size reduction). At five years the differences in HbA1c were massive – 2.1 points vs. 0.3 points improvement over baseline. The surgical group were thinner, had improved blood fats and reported better quality of life.

So what are the service implications of this iconic study? We need to ‘industrialise’ surgery, so that more operations can be done at a given cost. That means teams of technicians operating under consultant (anaesthetist and surgeon) supervision. Here is an artist’s representation of such a ‘Taylorised’ process:

Such a process was established to improve access to cataract surgery in Moscow over three decades ago.[2] Similar processes have been used with respect to open heart surgery in the US. I propose we should conduct simulations and then move gradually and incrementally to a safe, but efficient, method of implementing high-throughput bariatric surgery. Evaluation of the roll-out would be essential. Barriers will need to be overcome, but one or two effective demonstration sites will speak more than volumes of words. My only real concern is that some new ‘technology’ will come along and sweep away bariatric surgery and all its (protesting) practitioners.

— Richard Lilford, CLAHRC WM Director

References:

1. Schaeur PR, Bhatt DL, Kirwan JP, et al. Bariatric Surgery versus Intensive Medical Therapy for Diabetes – 5-Year Outcomes. New Engl J Med. 2017; 376: 641-51.
2. Schmemann S. Moscow Eye Doctor Hails Assembly-Line Surgery at Clinic. The New York Times. 2 July 1985.

Wait Until Your Symptoms are Really Bad Before Having an Osteoarthritic Joint Replaced

Early studies of hip replacement showed that the operation was associated with large and sustained QALY gains, and hence that it was cost-effective. The same applied to knee replacement. The patients in these studies all had severe disease, as shown by their quality of life scores at baseline. But indications for both operations have gradually expanded so that the majority of current patients who receive the operation are atypical of those in the original studies. That is to say, their disease is less severe. The long-term benefits of hip replacement have been found to be modest in recent studies, doubtless because patients with less severe disease have less capacity to benefit.[1] Now a large American study [2] has reported similar findings with respect to knee replacement, confirming that the operation is only cost-effective in people with severe pain and  limitation of movement at baseline. As in many medical/surgical treatments it is important to stratify by baseline severity. Absolute (and sometimes relative) benefits fall as baseline severity decreases, thereby radically shifting the harm to benefit ratio.

— Richard Lilford, CLAHRC WM Director

References:

1. Beswick AD, Wylde V, Gooberman-Hill R, Blom A, Dieppe P. What proportion of patients report long-term pain after total hip or knee replacement for osteoarthritis? A systematic review of prospective studies in unselected patients. BMJ Open. 2012; 2: e000435.
2. Ferket BS, Feldman Z, Zhou J, et al. Impact of total knee replacement practice: cost effectiveness analysis of data from the Osteoarthritis Initiative. BMJ. 2017; 356: j1131.

Theory of Mind in Tennis

On Tuesday nights I play tennis with my friends; Zac, Boris and Sergei (not their real names). CLAHRC interventions are often heavily based on behaviour change, and so I have had to brush up on my psychology. But is this knowledge of any use in tennis? In the following few editions of the News Blog I shall explore the modern psychological theory in the context of my feeble attempts at tennis. I shall start with the idea of a “theory of mind”, most often related to Tomasello.[1] [2]

Zac hates it when I intercept his powerful return of serve. So I know that when my partner, Sergei, next serves to the seething Zac, he will be predisposed to punish my impecuniousness by hammering his return down my tram line. To reduce this risk I should position myself towards the edge of the net. But Zac knows that I know that he is seething, and therefore that I will anticipate the tramline shot. He will anticipate my preventive action, which would open up the centre of the court, enabling him to pass me and place the ball on my partner’s backhand. So, I must anticipate his anticipation… This is an archetypal example of a theory of mind – the ability of humans to anticipate the effects of their actions in the mind of other humans. If Zac and I could undergo functional MRI on the court, then the complementary parts of our brains would brighten up in a kind of dance. So, I position myself if an intermediate position – I do not cower over the tramline, nor do I move aggressively to mid-court. Zac has three options – risk the tramline shot, go for mid-court, or play a standard cross-court shot. If he has read my reading of his reading of my mind, he will go cross-court. But what if he has anticipated I have anticipated that he has anticipated!

— Richard Lilford, CLAHRC WM Director

References:

1. Carpenter M, Nagell K, Tomasello M. Social cognition, joint attention, and communicative competence from 9 to 15 months of age. Monogr Soc Res Child Dev. 1998; 63(4): 1–143.
2. Tomasello M, Carpenter M, Call J, Behne T, Moll H. Understanding and sharing intentions: The origins of human social cognition. Behav Brain Sci. 2005; 28: 675–735.

Private Consultations More Effective than Public Provision in Rural India

Doing work across high-income countries (CLAHRC WM) and lower income countries (CLAHRC model for Africa) provides interesting opportunities to compare and contrast. For example, our work on user fees in Malawi [1] mirrors that in high-income countries [2] – in both settings, relatively small increments in out-of-pocket expenses results in a large decrease in demand and does so indiscriminately (the severity of disease among those who access services is not shifted towards more serious cases). However, the effect of private versus public provision of health care is rather more nuanced.

News Blog readers are likely aware of the famous RAND study in the US.[3] People were randomised to receive their health care on a fee-for-service basis (‘privately’) vs. on a block contract basis (as in a public service). The results showed that fee-for-service provision resulted in more services being provided (interpreted as over-servicing), but that patients were more satisfied clients, compared to those experiencing public provision. Clinical quality was no different. In contrast, a study from rural India [4] found that private provision results in markedly improved quality compared to public provision, albeit with a degree of over-servicing.

The Indian study used ‘standardised patients’ (SPs) to measure the quality of care during consultations covering three clinical scenarios – angina, asthma and the parent of a child with dysentery. The care SPs received was scored against an ideal standard. Private providers spent more time/effort collecting the data essential for making a correct diagnosis, and were more likely to give treatment appropriate to the condition. First, they compared private providers with public providers and found that the former spent 30% more time gathering information from the SPs than the public providers. Moreover, the private providers were more likely to be present when the patient turned up for a consultation. There was a positive correlation between the magnitude of fees charged by private providers and time spent eliciting symptoms and signs, and the probability that the correct treatment would be provided. However, the private providers are often not doctors, so this result could reflect different professional mix, at least in part. To address this point, a second study was done whereby the same set of doctors were presented with the same clinical cases – a ‘dual sample’. The results were even starker, with doctors spending twice as long with each patient when seen privately.

Why were these results from rural India so different from the RAND study? The authors suggest that taking a careful history and examination is part of the culture for US doctors, and that they had reach a kind of asymptote, such that context made little difference to this aspect of their behaviour. Put another way, there was little headroom for an incentive system to drive up quality of care. However, in low-income settings where public provision is poorly motivated and regulated, fee-for-service provision drives up quality. The same seems to apply to education, where private provision was found to be of higher quality than public provision in low-income settings – see previous News Blog.[5]

However, it should be acknowledged that none of the available alternatives in rural India were good ones. For example, the probability of receiving the correct diagnosis varied across the private and public provider, but never exceeded 15%, while the rate of correct treatment varied from 21% to about 50%. Doctors were more likely than other providers to provide the correct diagnosis. A great deal of treatment was inappropriate. CLAHRC West Midlands’ partner organisation in global health is conducting a study of service provision in slums with a view to devising affordable models of improving health care.[6]

— Richard Lilford, CLAHRC WM Director

References:

1. Watson SI, Wroe EB, Dunbar EL, et al. The impact of user fees on health services utilization and infectious disease diagnoses in Neno District, Malawi: a longitudinal, quasi-experimental study. BMC Health Serv Res. 2016; 16: 595.
2. Carrin G & Hanvoravongchai P. Provider payments and patient charges as policy tools for cost-containment: How successful are they in high-income countries? Hum Resour Health. 2003; 1: 6.
3. Brook RH, Ware JE, Rogers WH, et al. The effect of coinsurance on the health of adults. Results from the RAND Health Insurance Experiment. Santa Monica, CA: RAND Corporation, 1984.
4. Das J, Holla A, Mohpal A, Muralidharan K. Quality and Accountability in Healthcare Delivery: Audit-Study Evidence from Primary Care in India . Am Econ Rev. 2016; 106(12): 3765-99.
5. Lilford RJ. League Tables – Not Always Bad. NIHR CLAHRC West Midlands News Blog. 28 August 2015.
6. Lilford RJ. Between Policy and Practice – the Importance of Health Service Research in Low- and Middle-Income Countries. NIHR CLAHRC West Midlands News Blog. 27 January 2017.

The New and Growing Interest in Mental Health: Where Should it Be Directed?

Mental health provision and mental health research are undergoing something of a renaissance. The subject has been the priority of successive governments, more people are entering mental health professions, and mental health attracts a financial premium under the Research Evaluation Framework, through which universities receive care funding. The biological basis of many mental health diseases has recently been unravelled – see for instance past News Blogs on the molecular biology of schizophrenia, and Alzheimer’s disease.[1] [2] From a philosophical standpoint the mind is now seen as a function of the brain, just as circulating the blood is a function of the heart. The interaction between the brain and the rest of the body, first discovered by observations on Alexis St. Martin in 1822, and later seen in ‘Tom’ in 1947,[3] is now a major source of investigation (see another article in this News Blog on a part of the brain called the amygdala).

>Much of this renewed attention on mental illness carries the, often implicit, implication that mental health treatment should improve. This is undoubtedly the case for many diseases at the severe end of the psychiatric spectrum. One does, however, have to wonder whether the traditional medical model that serves us well in diseases such as schizophrenia and autism, is really the right way to go for other conditions such as depression and anxiety, especially in their milder forms. Depression, one often reads, affects 30% of the population. But 30% represents a choice of threshold, since the definition of ‘caseness’ turns on where the line is drawn. If set at roughly one-third of the population one has to wonder about the logistics of supplying sufficient treatment. And even if the logistics can be managed, it still seems wrong to make ‘cases’ of fully a third of the human race. To put this another way, common problems, such as depression and obesity are best tackled at the societal level. Therapeutic services can then deal with the most serious end of the spectrum – people who really should be given a diagnostic label. This would seem to be the way to go for (at least) two reasons. First, many people (especially at the milder end of the spectrum, where normality elides into diseases) do not present to health services. Their mental health is important. Second, the brain is a ‘learning machine’ and it is hard to reverse harmful behaviours, such as eating disorders, once they have been firmly encoded in neural circuits. Mental health practitioners therefore have a preventive / public health responsibility to intervene by encouraging a wider ‘psycho-prophylactic’ approach. And this topic needs research support every bit as much as therapy. A population level approach would seem to have two broad components – a supportive environment, and encouraging resilience in the population.

Let us consider a supportive environment. Reducing bullying in schools is an archetypal example of an intervention to create a psychotropic environment. There is clear and present evidence that the victim (but not the perpetrator) is harmed by bullying, and there is also good evidence that the problem can be prevented.[4] How a psycho-therapeutic environment may look in other respects is less clear-cut. Workplace culture is likely to be important. The Whitehall studies show that a feeling of powerlessness is associated with stress and illness,[5] but putting this right is not a simple manner. For example, it is widely believed that an optimistic, or so-called ‘positive’, outlook is helpful in the workplace, but the experimental evidence actually points the other way. Being realistic about difficulties ahead and (often low) chances of success, is more helpful than a culture of poorly titrated optimism.[6]

There are many specific groups that are at risk of mental suffering and where environmental modification may help. While the workplace is stressful and a source of anxiety and depression, it has its antithesis in the loneliness that often accompanies old age. There is a fashion to try to keep everyone living independently in their homes for as long as possible. However, such an environment is likely to lead to increasing isolation. I think that communal living should be encouraged in the declining years between retirement and death.[7]

What about resilience in the population? To a degree, the workplace will always be stressful since competing interests and time pressures are inevitable. How can we increase resilience? Taking part in guides and scouts is associated with better mental health outcomes in young people.[8] Exercise has positive benefits on mental health across the age spectrum,[9] and team sports seem particularly beneficial. It is possible that we can encourage ‘mental hygiene’ by talking about it and encouraging healthy mental behaviours. I have a tendency to self-pity and so practice a kind of cognitive behavioural therapy on myself – I think of role models and count my blessings. Others practice ‘mindfulness’. We need to learn more about how to build resilience through experience. Where lies the balance between a bland life devoid of competition, and a ruthless environment creating ingrained winners and losers? I hypothesise that an environment where people are encouraged to have a go, but where coercion is avoided and failure is seen as par for the course, will prepare children for life’s vicissitudes. However, I suspect we are in the foothills of discovery in this regard.

There is always a temptation to screen for illness when it cannot be fully prevented, but the screening can often do more harm than good, and this is true in mental health as well as a physical context. Certainly, routine debriefing after a major incident or difficult childbirth appears to be at best unhelpful. CLAHRC WM collaborator Swaran Singh and colleagues showed that screening for the prodromal symptoms of schizophrenia is also unhelpful as it produces an extremely high false positive rate.[10] Again, working out when screening is of net benefit is an important task for the future.

In conclusion, none of what I have written should be seen as a criticism of therapeutic research and practice. Rather, I argue for a broadening of scope, not only to find things that are predictive of poor mental health, but to find workable methods to improve mental health at a population level. Public mental health is an enduring topic in CLAHRC WM.

— Richard Lilford, CLAHRC WM Director

References:

1. Lilford RJ. Psychiatry Comes of Age. NIHR CLAHRC West Midlands News Blog. 11 March 2016.
2. Lilford RJ. A Fascinating Account of the Opening up of an Area of Scientific Enquiry. NIHR CLAHRC West Midlands News Blog. 11 November 2016.
3. Wolf S. Stress and the Gut. Gastroenterol. 1967. 52(2):288-9.
4. Menesini E & Salmivalli C. Bullying in schools: the state of knowledge and effective interventions. Psychol Health Med. 2017; 22(s1): 240-53.
5. Bell R, Britton A, Brunner E, et al. Work Stress and Health: the Whitehall II study. London: Council of Civil Service Unions / Cabinet Office; 2004.
6. Lilford RJ. Managing Staff: A Role for Tough Love? NIHR CLAHRC West Midlands News Blog. 2 September 2016.
7. Lilford RJ. Encouraging Elderly People to Live Independent Lives: Bad Idea? NIHR CLAHRC West Midlands News Blog. 16 April 2014.
8. Lilford RJ. Does Being a Guide or Scout as a Child Promote Mental Health in Adulthood?. NIHR CLAHRC West Midlands News Blog. 25 November 2016.
9. Lilford RJ. On the High Prevalence of Mental Disorders. NIHR CLAHRC West Midlands News Blog. 7 March 2014.
10. Perry BI, McIntosh G, Welch S, Singh S, Rees K. The association between first-episode psychosis and abnormal glycaemic control: systematic review and meta-analysis. Lancet Psychiatry. 2016; 3(11): 1049-58.

Another Excellent Paper on Economic and Mortality Inequality from Currie & Schwandt

In the latest News Blog [1] (before the election purdah) I covered Case and Deaton’s monumental study of death rates among white people in the US.[2] I briefly mentioned the idea that childhood (and even pre-natal) exposure can ‘programme’ the body, leading to mortality differences in later life. This can lead to exaggerated estimates of the effects of economic conditions and behaviours in later life on health and life expectancy. There is strong evidence that patterns of behaviour in adulthood are laid down by the age of three.[3] Failure to give due consideration to prior conditions can also lead to poor interpretation of life expectancy statistics. Life expectancy (say at birth) is derived, perforce, from the current age-specific mortality rates at all (subsequent) ages.[4] So there is an assumption that when a baby born in 2017 reaches age 40, she or he will be subject to the current mortality rates for 40 year olds, and so on. That is a massive assumption, given the above point concerning early childhood effects on adult health.

The subject of wealth and health is replete with academic bear traps. Mortality is rising among poor white people,[5] as we pointed out in a previous News Blog.[6] But then the composition of poor white people changes over time. So the mortality of poor white 40 year old women cannot automatically be ascribed to any recent change in the behaviours or exposures of such women. It could be attributable to their early life exposures. Likewise, Hispanic children have been dropping out of school in the US at progressively lower rates. So any observation comparing the health of drop-outs over time is highly biased – the same types of people are not being compared. And when it comes to ethnicity, things get harder still because the way ethnic groups are classified is ephemeral.

Currie and Schwandt use counties in the US as the basis for comparative statistics.[7] They use three year averages to reduce noise, and they measure the socio-economic standards of counties in different ways – poverty rates, high-school completion rates, and median income. They look at age-specific death rates, life expectancy (as a consolidated measure of death rates over all ages), and age/sex adjusted differences by race.

What do they find in their study covering the years 1990-2010?

1. Life expectancy is increasing across the US, but us doing so to a greater extent in poorer areas than in richer ones.
2. This relative improvement in poor counties compared to rich counties is seen particularly among women.
3. And in children under the age of five (see a previous News Blog [6]).
4. Inequalities in death rates in young adults are also declining.
5. But over age 50, inequalities in mortality increased for women while remaining unchanged in men.
6. For black children, inequalities narrowed compared to white children.
7. The increased health inequality of white adults cited in our last News Blog is confirmed (phew!).

There are other interesting findings. I would have thought that immigrants would have worse outcomes than age and race matched residents, but the opposite is the case – at least for Hispanic people. A massive study of identical twins separated at birth would be needed to sort out cause and effect relationships (and even that would not be perfect). However, taken in the round, the news from the USA is good regarding inequalities; poor white people aside. Let me therefore end with a quote from the article – you can make of it what you will:

“It sometimes seems as if the research literature on mortality is compelled in some way to emphasize a negative message, either about a group that is doing less well or about some aspect of inequality that is rising.”

— Richard Lilford, CLAHRC WM Director

References:

1. Lilford RJ. Ever Increasing Life Expectancies Come to an Abrupt End Among American Whites. NIHR CLAHRC West Midlands News Blog. 5 May 2017.
2. Case A, & Deaton A. Mortality and morbidity in the 21st century. Brookings Papers on Economic Activity. BPEA Conference Drafts. March 23-24, 2017.
3. Suzuki E, & Fantom N. What does “life expectancy at birth” really mean? The DATA Blog. 11 November 2013.
4. Lilford RJ. More on Brain Health in Young Children and Effect on Life Course. NIHR CLAHRC West Midlands News Blog. 24 February 2017.
5. Chetty R, Stepner M, Abraham S, et al. The Association Between Income and Life Expectancy in the United States, 2001-2014. JAMA. 2016; 315(6):1750-66.
6. Lilford RJ. Relative Wealth and Health. NIHR CLAHRC West Midlands News Blog. 6 May 2016.
7. Currie J & Schwandt H. Mortality Inequality: The Good News from a County-Level Approach. J Econ Perspect. 2016; 30(2): 29-52.

Brain Activity and Heart Disease – a New Mechanism

The amygdala is a key component in the ‘salience network’ of the brain. This network is activated in conditions of fear and stress. A recent elegant paper in Lancet [1] examined the relationship, first, between amygdala activation (measured by PET scanning) and cardiovascular outcomes, and second, between activation of the amygdala and certain mediators of cardiovascular disease concerned with stimulation of bone marrow to produce inflammatory cells and with arterial inflammation. They showed positive correlations in all cases. I am interested in causal modelling,[2] [3] and I was therefore provoked by the authors’ ‘mediation model’, which I take to be a form of structural equation modelling. This suggested that only half of the amygdala’s ‘effect’ on cardiovascular disease could be explained by the two mechanisms proposed above (production of inflammatory cells and arterial inflammation). This paper represents a potential step change in understanding brain-body interactions, but I await replication with interest.

— Richard Lilford, CLAHRC WM Director

References:

1. Tawakol A, Ishai A, Takx RAP, et al. Relation between resting amygdalar activity and cardiovascular events: a longitudinal and cohort study. Lancet. 2017; 389: 834-45.
2. Lilford RJ, Girling AJ, Sheikh, et al. Protocol for evaluation of the cost-effectiveness of ePrescribing systems and candidate prototype for other related health information technologies. BMC Health Serv Res. 2014; 14: 314.
3. Watson SI & Lilford RJ. Essay 1: Integrating multiple sources of evidence: a Bayesian perspective. In: Challenges, solutions and future directions in the evaluation of service innovations in health care and public health. Southampton (UK): NIHR Journals Library, 2016.