Lecture 22r copy PDF: Starvation and Its Effects

Conclusion • Acceptance of a body size which is healthy, irrespective of societal norms, should be seen as a more desirable goal than a loosing battle against ones physiology • How do you teach people to accept their bodies, but on the other hand to feel motivated to avoid becoming obese with its as...

Conclusion • Acceptance of a body size which is healthy, irrespective of societal norms, should be seen as a more desirable goal than a loosing battle against ones physiology • How do you teach people to accept their bodies, but on the other hand to feel motivated to avoid becoming obese with its associated health risks? • This is a major problem without an easy solution 31 31 Starvation Appetite: The psychology of eating and drinking 32 32 Introduction • In this lecture we will consider the sociopsychobiology of starvation – – – – – Demographics Famine Physiological effects Psychological effects Lifespan extension 33 33 Demographics • How many people are currently malnourished and where are they? – World population is 7.6B and roughly 1B are malnourished • • • • • Estimates vary and severe malnourishment may cover - 0.5-20% (total pop.) Milder forms – up to 50% (total pop.) Even in the USA malnourishment may affect 0.5 Million children Children may be the most adversely affected (school attendance; biological effect on IQ) Asia and Africa have the highest incidence (green and especially blue areas below) 34 34 Some definitions • Malnourishment may be chronic or acute – Chronic malnourishment in children can cause stunting (defined as height for age is greater than 2 SD below Mean) – Acute malnourishment in children/adults causes wasting (as does chronic malnourishment in adults) • Chronic malnourishment is the norm, with exacerbations (acute) under times of famine • Famine typically does not occur in a vacuum, it usually occurs within the context of on-going societal problems • Famine inevitably concentrates every ones mind, as it is highly visible (if one can look) • Consequently, famine has been well studied 35 35 Famine – An historical perspective • Europe – Since the Roman invasion 190 famines in England - last in 1620 – Last famine in Ireland, 1846-51 – not one that history could forget! – By the mid 1800’s famines were largely ‘history’ here except for WWII • Dutch famine ‘44 [20K], Leningrad siege ‘41-44 [1-1.5M] • Asia – 90 Major famines in the last 2500 years – 66% of these have occurred since 1700 – Some of the worst have occurred in the last 50 or so years • China (1959-61), 15-43 M dead (political; the ‘difficult three-year period’). Land collectivisation, chaotic management, USSR pseudoscience [close planting, deep ploughing, killing birds], plus floods & drought led to one of the world’s worst famines • Bangladesh (1974), 1 M dead (flooding) • North Korea (1996), 0.2-3.5 M dead (political; the ‘arduous march’) • Africa (a similar picture to Asia) (e.g., Sudan ‘98, 70K) • The picture is not all doom and gloom – After WWII, the number of people per year living in famine afflicted areas was 790M, this has consistently declined over the years to less than 200M now 36 36 Chronic malnourishment in kids Stunting in 2-5 year olds 37 37 Chronic malnourishment in adults 38 38 Famine - Types & Theories • Theories of how famines come about can be broadly categorised into two • Those that emphasise human catastrophes • Genocide, war, preexisting social unrest, unstable social structures, poverty, poor government, poor communications • Those that emphasise natural catastrophes • Plagues, tempests, flooding, drought • Pure examples of either are rare, as both factors generally combine • Great Chinese famine is one example. The Irish potato famine is another – Absentee landlords, British indifference, sole reliance on the potato combined with potato blight... 39 39 Consequences of famine • The social trajectory of famine – The moral economy (i.e., sources of informal support) – Agrarian workers and landlords/employees – Relationship to family, neighbour, tribe – Religion – – – – – Reduced food intake and meal spacing Use of wild foods (frogs, rats, seaweed, grass…) Sale of non-essential possessions (cooking gear) Sale of all possessions (farming implements, land) – The PNR Migration • To cities/towns (slum-dwelling) and refugee camps – High morbidity from unclean water - GI tract infections - aided by reduced immune function from malnourishment 40 40 Physiological effects of famine • Famine affects people in different ways – Children suffer because they require far more protein than adults – The health of the foetus may be adversely compromised which may have demographic consequences decades later – Deaths usually first hits the elderly, infants, then adult males – Women and older children are often the last to die • We will now look at the effects of famine on children, pregnant women and adults… 41 41 Children • PEM (Protein/Energy malnourishment) • PEM has two extremes • Marasmus (defn: wasting away) results from a diet insufficient in calories (energy) • Kwashiorkor (defn: ‘the disease a baby gets when a new baby is born’ – from the Ivory Coast, W. Africa) results from a diet sufficient in calories, but insufficient in protein • In a famine children will typically fall on a continuum between these extremes 42 42 Marasmus (calories) • Symptoms • Extreme underweight for age (60% below the 50th percentile) • Irritable, crying, apathy • Wizened, shrunken • Chronic diarrhea • Treatment/outcome • Refeeding and hydration • Opportunistic infection 43 43 Kwashiorkor (protein) • Symptoms • Edema • Sores (skin, membranes) • Treatment/outcome • Rapidly fatal if untreated • Milk is best treatment • Long-term effects of PEM – These can be partially reversed but the effects are often long lasting 44 44 Long term effects of PEM • PEM is associated with long term disadvantage – 50% of PEM sufferers later have an IQ < 90, compared to a similar but non-PEM cohort (17%) – Apart from IQ, PEM is also associated with attention and STM problems 45 45 Pregnancy • Severe malnutrition of the mother results in spontaneous abortion (up to 4 weeks into pregnancy) • Malnutrition alone definitely: • Reduces brain weight, and number of neurons and glia – Not surprising as 250,000 neurons per minute are grown during fetal development • Has effects that are irreversible by good nutrition later in life • It has been suggested: • That raised BP, proneness to Type II diabetes and heart disease may all be consequences of poor maternal nutrition • Epigenetic basis studied in the Dutch famine cohort (1944) 46 46 Adults • Severe malnourishment in adults has a range of physiological effects – It produces impotence in men and eliminates the menstrual cycle in women – Loss of lean and fat body mass – Lowered heart rate, Basal metabolic rate & Blood pressure • Females may be able to reduce BMR further than men, which may explain their greater ability to survive famine – Edema – Lethargy and hypersensitivity to cold – Severe impairment of immune function • It is usually the latter which kills, in combination with the unsanitary conditions prevalent in such situations 47 47 Laboratory studies • The physiological and psychological effects of malnourishment were studied in a landmark US 1 year experiment • This 1940’s study aimed to find out the best way of refeeding victims of famine in war-torn Europe and the effect that refeeding would have on their physiology and behaviour • Keys had 32 conscientious objectors, volunteer for the starvation study • The initial 3 months were baseline observation followed by 6 months of a semi-starvation diet (equivalent to that of war torn Europe), followed by 3 months refeeding • Extensive physiological and psychological tests were conducted 48 48 The Keys study • The men were housed, fed and slept at the University of Minnesota for the whole length of the study • The regime: – Observation period » Average weight 70Kg (3500 Kcal) – Starvation period – Post weight 53Kg (on a 1570 Kcal diet) – They had to walk several kilometres everyday » Strength decreased 30% » Body temp dropped so that even at the height of summer they needed 3 or 4 blankets » BMR dropped 40% (saving 600Kcal) » Pulse dropped from 56 to 38 BPM and heart volume shrunk by 20% » Edema in wrists and ankles & excessive urination – Refeeding period – 1877-4158Kcal, then all at 5218Kcal – Weight regain was at the cost of lean body mass 49 49 Psychological effects • Baseline period – All willingly participated and were full and engaged participants for the first part of the study • Starvation period – Numerous psychological effects were observed, but no change in IQ or memory measures • • • • • • • • Apathy, depression, tiredness Irritability Loss of spontaneous activity Narrowing of interests Loss of libido Loss of interest in personal appearance Violence in 2 men Little interest in carrying out their routine duties 50 50 Psychological effects • A major finding (perhaps not surprisingly) was food preoccupation • • • • • • • • Thoughts and talk continuously on food Recipe and cookbook collecting Planning how they would eat the next meal All food dislikes disappeared and the monotonous diet of cereals, potatoes and turnips (28g of protein & 22g fat) got to be liked more and more Heightened possessiveness about food Meals could last up to 2 hours Extreme reactions if anyone wasted food Extensive gum chewing, nail biting and smoking – One man consumed 40 packs of gum per day 51 51 Psychological effects • A further area of study was the effect on social interaction between the men, which had initially been very positive and was described by Keys as “tolerant, happy and lively” – – – – The tone became somber, serious and the humour sarcastic All participants became highly ego-centric Social interaction became stilted and artificial The men became unable to control outbursts of temper etc, even though they were aware of their irritability • Refeeding had to be postponed by a week, which prompted a near rebellion by the participants. When it started it too had profound psychological effects – Table manners were totally abandoned – Attitudes were expressed at total odds with those reported early in the study (ego-centric) – This is clearly illustrated in Samuel Legg’s account of his experiences as a participant in this study… 52 52 Participant’s voices • Samuel Legg (pictured below before and during the study)… • “…The psychological aspects of starvation are unbelievable. We went there because we were concerned about people abroad and wanted to do what we could to help those less fortunate than ourselves, and I think we lost that feeling after about two months. At the end of 5 months of starvation our attitude was “to heck with the people abroad; I am hungry”. That was all that was important. The only important thing left was whether I was ever going to get food. I was only interested in myself…” • After 3 months of refeeding most of the psychological effects had dissipated, but further studies with other populations suggest that the psychological effects of starvation are lifelong 53 53 Long-term psychological effects • Several studies have looked at the effects of periods of starvation on peoples later behaviour towards food • This has typically focused on concentration camp survivors • One key finding has been that such survivors are far more likely to binge eat than controls who went through a similarly stressful experience • The problem here, of course, is that we can not be certain that starvation alone produced this (although some of Ancel Keys participants later behaved in the same manner) • Another interesting study interviewed holocaust survivors about their attitudes to food 54 54 Long term effects… • Many camp inmates received somewhere between 7001600 Kcal/day and some as low as 500-900 Kcal/day • The Nazi authorities (by their own admission) estimated that a healthy man could expect to live for around 3 months on this sort of diet (watery soup & bread) • Not only was this far less than in the Keys study, many had to engage in very hard labour as well as witnessing traumatic events on a daily basis • When interviewed some 50 years after the fact the survivors reported the following long term effects on their attitudes to food 55 55 Survivors report… • Extreme reactions to throwing out food • These also occur even when food is spoiled • Storing excess food (e.g., putting bread in bedside drawers) • Difficulty standing in line for food • Anxiety if food is not available in the immediate vicinity • Craving for carbohydrates 56 56 Food deprivation and longevity • So far, we have focused solely on the costs of starvation and semi-starvation, but nearly 80 years of experimental research using various animal models has suggested that some form of dietary restriction may significantly increase lifespan • We will finish this lecture by looking at this rather bizarre twist to the science of starvation 57 57 Effects of food deprivation • In 1934 McCay and Crowell demonstrated that rats fed a reduced caloric diet lived twice as long as control rats • These findings have been replicated many times in a diverse range of animals from fruit flies to mammals • Maintaining a youthful appearance • Higher activity levels • Delays in developing age-related diseases • However, semi-starvation diets do not result in extended lifespan in Rhesus monkeys (the closest test yet to trying this in humans) • Semi-starvation diets are difficult to test in humans… • Infants can not be assigned to either a calorie restricted treatment group or a normal control group! • Nonetheless a study started with older participants in 2002 indicates benefits for reduced BP • Some suggest this study is flawed as the effects of caloric restriction may only work when the animal/person is young 58 58 Why might food deprivation lengthen life-span? • Hormesis (‘excitation’) hypothesis • Low intensity biological stress may put the organism into a ‘defensive state’ which slows metabolism and ageing • Perhaps such a state could be initiated without using a starvation diet by promoting physiological factors that generate leanness? • Free radicals • Mitochondria generate more free radicals when energy is abundant • According to this theory it is free radicals which promote cell ageing • Cutting calories cuts free radicals, thus slowing ageing • Currently, how food deprivation extends life span is not understood – and similarly, we do not really know whether it will occur in humans 59 59 Conclusion • Malnourishment is a considerable problem and the cause of many preventable premature deaths • Psychologically, the effects of food deprivation share something in common with what we already know about dieting • In the next lecture we will see this relationship presented in even starker form when we examine anorexia and bulimia 60 60