LECTURE 4: Early Exposure Latent Effects LECTURE NOTES AND SUPPLEMENTARY READING NOTES

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Department
Health Studies
Course
HLTC23H3
Professor
Jason Ramsay
Semester
Summer

Description
LECTURE 4: Early Exposure: Latent Effects June 04, 2012 The Dutch Hunger Winter, 1944-45 -during WWII, the advance to push the German army from Western Europe combined with a very harsh winter to cut off most of The Netherlands from food supply -the Dutch had to severely ration food and scrounger for essentials -a famine ensued which lasted for a 5 month period -retrospective cohort research shows that the famine had a profound effect on the gestating fetus -canals had frozen and food could not be transported overland -by November 1944 rations had fallen to about 1000 calories per day -between December 1944-April 1945,r ations had fallen to 400-800 calories -eventually, the extra ration for pregnant women were not available -this terrible famine had a specific course -therefore, the effects of various levels of caloric restriction can be studied -in some ways, it is like a naturalistic experiment because the differential interaction of critical periods and caloric deficits can be examined -immediate effects: -had a profound effect on the health of the general population -mortality increased 2x over 1939 -extra death rate due to starvation -however, women were still conceiving and giving birth to babies -it is in these babies that we can see the effect of early malnutrition on health in adult life -prenatal exposure to famine: -all babies (no twins) born between November 1, 1943 and February 28 , 1947 were eligible for inclusion in the study -of the total cohort, 1018 people living close to or in Amsterdam were approached, 912 agreed to be interviewed, 741 consented to undertake glucose resistance testing -average age was 50 -effects of early famine on later health: -it turned out that meticulous birth records had been kept -they had info on mothers weight and health and the size of the baby and placenta -the baby was exposed to famine if the average daily ration during a 13 week period of gestation was below 1000 calories -how was the group divided: -the group was divided into late gestation, mid-gestation and early gestation exposure -control group considered of participants born before or after the famine period -in the analysis of the data, they controlled for other factors such as gender, SES, smoking and BMI -what were the effects at birth? -babies exposed to famine in late or mid gestation were lighter, shorter, thinner and had smaller head circumference -exposure meant a smaller placenta -babies exposed to famine in early gestation were slightly heavier and larger on average -later effect: -people exposed to famine had impaired glucose tolerance, meaning that they had a much higher risk for diabetes -exposure in mid-gestation was linked to an increase in obstructive airway disease -babies exposed to famine in first trimester showed the striking effects -maternal malnutrition during the first trimester -3X the normal rate of coronary heart disease -atherogenic lipid profile (meaning that they are at greater risk for clots and plaque in veins) -more obesity, raised levels of fibrinogen -decreased levels of Factor VII -self-rated health: -the proportion of participants that reported poor self-rated health was significantly greater -poor self-rated health is a very good indicator of risk of imminent death -more effects: -there was a relationship between smallness at birth and raised blood pressure -increased carbohydrate protein ratio during the third trimester was associated with increased blood pressure, regardless of famine exposure -overall, famine exposure significantly increased risk of chronic disease later in life -interesting points: -rates of disease appeared to be unrelated to maternal robustness -selective survival cannot account for the differences seen in the famine/non-famine comparison -possible that it was not famine alone, but a sudden and profound metabolic change due to feast/famine transition that affected the fetus -maternal/prenatal forecasting: -studies show that the nature of the maternal environment can affect physical characteristics of the fetus -voles will develop thicker fur if it turns out they will be born in the winter -what happens if the maternal forecast is out of joint with the actual conditions that the baby faces at birth -famine and neurological development: -one hypothesis for the origins of schizophrenia is subtle brain abnormalities that are present from birth -research also indicates that prenatal exposure to famine is implicated in brain abnormalities -famine effects on brain: -famine during the first trimester is associated with white matter abnormalities -in patients with schizophrenia, famine was associated with decreased intercranial volume -higher intercranial volume of first trimester famine exposed, but health was larger than controls -other research shows that famine also causes damage to the HPA axis -likely leads to poor development of the white matter -so what does this mean? -environmental factors influence early brain development -inadequate supply of nutrients cannot health the body replace normally metabolized myelin -loss of myline leads to reactive gliosis (inflammation, a sign of damage) -the research argues that there is an interaction between genetic factors and environmental factors to produce long term mental health effects -recent research:-Reijneveld study (2006) looked at behavioural data gathered on a representative group of children -were interested in psychopathology as well as academic functioning -compared very low birthweight (VLBW) and very preterm (VP) children at age 5 to groups of normal birthweight 5 year olds -low BW = under 1500 grams at birth -measure: -The Child Behaviour Checklist was used to assess child behaviour issues -the prevalence rate (the total number of cases of the disease in the population at a given time) for social and emotional problems was must higher in the VLBW and VP children -results: -CBCL was completed by parents -assessment by paediatrician -characterisitcs between groups were matched as much as possible (only maternal education was different) -VLBW children scored significantly higher on measures of externalizing problems -they did not differ on measures of internalizing problems -externalizing problems are behaviour and social interaction problems -a common externalizing problem is attention deficit/hyperactivity syndrome Stress and gestation: Quebec Ice storm 1998 -facts: -46 people died in the ice storm, billions of dollars in damages -province of Quebec pop. 7.4 milion -3.2 million people lost electricity, s
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