“Metabolic Maladaptation: Individual and Social Consequences of Medical Intervention in Correcting Endemic Hypothyroidism”, 1999-11 (; backlinks):
Endemic hypothyroidism has been studied in a Central African population in remote Congo (ex-Zaire) to investigate the prevalence, severity, causes, and potential control of this disorder, with questions as to why this disease is conserved, and whether it confers any adaptive advantage in this resource-constrained environment.
Iodine deficiency, cassava goiterogens, and selenium deficiency were found to be the factors implicated in the severe hypothyroidism expressed in congenital cretinism and high goiter incidence in this isolated population, which continues to be under observation following medical intervention. Profound hypothyroidism was encountered in whole village populations as measured by serum thyrotropin determinations ranging from very high to over 1,000 IU, and thyroxin levels ranging from low to undetectable; cretinism rates were as high as 11% and goiter incidence approached 100%.
Assessment of endocrinologic status, caloric requirement, energy output, fertility, and ecologic factors was carried out before and during iodine repletion by depot injection.
Hypothyroidism was corrected and cretinism eliminated in the treatment group, with goiters reduced in most instances (with regrowth exhibited in some who escaped control) and some symptomatic goiter patients were offered surgical treatment for respiratory obstruction. Individual patient benefits, including improved strength and increased energy output, were remarkable. The social and developmental consequences observed within the collective groups of treated patients were remarkable for an increase in caloric requirement and a dramatic increase in fertility that led to quantitative as well as qualitative increases in resource consumption. Micronutrient iodine repletion was not accompanied by any concomitant increase in macronutrient supply, and hunger and environmental degradation resulted.
The highly prevalent disease of hypothyroidism is found in highest incidence in areas of greatest resource constraint. It may be that hypothyroidism is conserved in such areas because it may confer adaptive advantage in such marginal environments as an effect, as well as a cause, of underdevelopment. Hypothyroidism may limit energy requirements, fertility, and consumer population pressure in closed ecosystems that could otherwise be outstripped. Single factor intervention in a vertical health care program not sensitive to the fragile biologic balance and not part of a culture-sensitive development program might result in medical maladaptation.
[Keywords: micronutrient repletion, medical maladaptation, vertical health care programs, conserved diseases, fertility and population pressures, endocrinologic adaptation response]
…The study was carried out personally under the auspices of a mission station associated with Africa Inland Mission, but without major funding sources or sponsorship. Some volunteer labor was contributed through the World Medical Mission which, along with the study’s volunteer participants, donated some of the supplies.
…One of the most severe endemias so far recorded on earth is the study region of this investigation in Central Africa. The area selected for this study of endemic hypothyroidism is in the upper reaches of what was called “Bas-Uele”, first recognized by colonial district officers when this area was “Congo Belge” and then reported by several Belgian investigators through preliminary surveys.18…Where Was This Study Conducted? This study was conducted in an Azande population through the longitudinal study of profoundly iodine-deficient populations in the Uele region of northeast Congo (at the time designated Zaire). This region, defined as ‘Sasaland’ (because of the hereditary chieftainship of the region bearing the Azande family name Sasa), is in a remote part of Central Africa (Figure 1) in which little study or intervention had previously been carried out or reported…The region under discussion is in equatorial central Africa (see Figure 1A) in a region subserved by an Africa Inland Mission (AIM) station based in Nyankunde.
…Those who are more affluent in this society and who may depend less on cassava as a principle intake (for example, the ruling Azande families) still are not free of goiter or cretinism and, in fact, Chief Sasa himself and the ancestral portraits of the ruling chiefs before him exhibit very prominent displays of goiter.
…How was this study conducted? Measurements and morphology applied in endemic hypothyroidism: The methods of the population survey and random selection of the intervention arm of the hypothyroidism study began with a population of 400 patients studied from 1984–3198737ya, expanded to 700 patients under observation from 1987–3199034ya, and carried forward from 1990 to the present, following the investigators leaving the field after 4,000 patients were treated (representing 10% of the population of the Sasaland sub-prefecture).
…Results Of Population Survey: Goiter prevalence was nearly universal. The WHO Class III goiters predominated (Table 5). In one village, not one adult who was not a cretin could be found without a goiter. Most of the population experienced the goiter itself as a benign condition, and accepted it as normal. Even some carved wooden figures or dolls were represented with goiters (Figure 14). A random photograph of any group of people would reveal obvious WHO Class III goiters apparent at a distance in nearly all (Figure 15). The estimation by one chief headman in a village called Ebale is that the population surveyed is 95% inclusive of his village population. This high prevalence of goiter appeared evenly spread through each decade of life.
An even more tragic preliminary finding from the population survey was an incidence of cretinism as high as 11% of the population. This number reflects the prevalence, that is, the number of surviving cretins, and discounts those so severely retarded that they did not survive birth or infancy. A potential bias was uncovered in the anomalously lower incidence in the village of Ebale when one of the elders from the village noted our special interest in two of the severely retarded neurologic cretins examined during the surveillance visit. This community leader said that he had been unaware of our interest in seeing all the cretins, as well as those with goiters. Some cretins had been hidden outside of the village since they were not the “citoyens” of which the village was necessarily most proud. But when reassured that all of the population was to be included in village surveys, they understood that meant 100% of the accessible population. Once we expressed an interest in the entire population, a number of other cretins were presented, bringing the total up to the 10% that had been observed in other villages.
…Even if alternate food stocks were available or introduced, and if they could be sustained in the marginal soils of the equatorial rain forest, their presence would lead to the classic “chicken and egg” dilemma. To invest the higher human energy needed for a much later yield of higher calorie basic food staples would not be easy given the current marginal subsistence levels, even if such substitution were ecologically possible.
When I have gone hunting with members of this population, volunteers to carry meat back from a kill are numerous. The parts most eagerly sought after are fat, often viscera, with offal preferred over lean skeletal meat. This reflects a craving for higher energy food value in animal fats. This craving for animal fats is rarely satisfied, given the marginal grazing capacity, the high incidence of Trypanosomiasis, and the heavy natural predation on and by large mammals in this wilderness area. Leopards and lions make livestock husbandry impossible, besides luring the predators close in to human habitation with the easy prey as bait. Elephant and buffalo herds can destroy a whole village’s collection of shambas in a single night, ruining a year’s effort at clearing and gardening. Hunting and gathering remain the principal sources of occasional high energy foods, and for a more predictable source of calories, palm oil is collected. Fats from animal or vegetable sources have similar energy content, but more craving develops for animal fat because of its flavoring and as an intermittent, unreliable supply of a special treat. …In this region, baboons and buffalo, as well as rats, deplete the supply of rice and peanuts, but leave the cassava root in the field and in storage…As dietary substitution is not always effective, perhaps advice on preparation of the dietary food staple would be appropriate. Rather than soaking the cassava roots in stagnant pits as seen in Figure 3, encouraging preparation by soaking the roots in running streams would seem to dilute and diminish the cyanide content in the course of the cassava preparation. This advice is counterintuitive to the majority of the population who would be principally concerned with losing some part of their food store in running water. This counsel was called “zungu za wazungu”, Swahili for the “white man’s madness”, as were a number of other non-acculturated suggestions. Even if this advice were accepted by an educable population who could understand the reason for its recommendation, it could not be generally followed. The tropics are marked by two distinct seasons—the rainy season and the dry season—and advice on soaking in running water would be impossible half the year.
…Since the team was in control of the injection process, the needles and syringes were sterilized and the risk of HIV transmission was controlled by non-reusable needles that were destroyed.
…Assessing The Outcome Of Intervention In Morphologic Changes:
The changes in function were even more remarkable than those changes noted in form. The most dramatic change observed in the morphology of patients with already established goiter or cretinism was one very encouraging fact very early on in the study: in comparison with the control group, there was not one cretin born in the group of women treated by iodine repletion! The control arm of this investigation was immediately stopped for all women of reproducing age and was broadened for inclusion of most children approaching school age.39
40 village leaders conducted a survey at 10y from the first intervention (June 1993) and unanimously reported remarkably positive changes in each of the individuals who had iodine repletion. With respect to each individual treated, there was qualitative improvement (with the already noted exceptions of the complications of hyperthyroidism that were made possible by iodine repletion—a condition known as “Jod-Basedow’s Syndrome”—and complications due to regrowth of intrathoracic goiter or other postoperative events). Statements made by those administering the program within Sasaland were very enthusiastic. Kongonyesi, the untiring logistical assistant for the extended project, said, “Thank you for the goiter project, it heals people very much, their minds and bodies as well.” Of the other health initiatives attempted within this decade and this region, it is the most successful program in terms of compliance, sustainability, and behavior changes.
The immediate effect of medical intervention in relief of hypothyroidism is dramatic in individual terms. With the rare exception of some medical complications of over-activity (as in the rare events of Jod-Basedow’s Syndrome) the effects of iodine repletion in nearly all individuals seem positive. Converting from the low-energy hypothyroid state to normal metabolic rate is a revolution in development potential measured in the individual patient. The individual successes within the program can be viewed in summation in smaller groups of that population before looking at the overall impact.
…3 of the mute (but not deaf) cretins began talking within 6–12 weeks post-injection. As all 3 lived in distant villages (more than 35 km) they were not influenced by the research team nor did they receive increased village attention, thereby escaping the Hawthorne effect. Several began drawing and many of them used tools for the first time.
…The “Downside” Of The Iodine Repletion Program In Individuals And The Society—Possible Negative Consequences Of Changes: Not only did fertility increase, but maternal and infant mortality decreased, resulting in an overall increase in the population. Each of these population members were also increased consumers, since caloric intake adequate for the minimal energy output of a cretin is not adequate to sustain a person with normal thyroid status and normal metabolic demands. The caloric requirement increased by at least a third for each of the individuals treated when they were relieved of hypothyroidism, and the increased number of these enhanced consumers has meant greater demand on the environment within the study area. Food production from that which is grown or gathered was marginal at the time of the original survey and not remarkably increased despite efforts to do so following medical intervention and the notable population increase during the period of the study.
The effects of medical intervention on the society as a whole have tempered the conclusions of an overall success in terms of individual improvement following medical intervention. As dramatic as the measurements of morphologic markers in individuals, the functional consequences were no less impressive both for individuals and the society composed of those affected when hypothyroidism was corrected. Energy output increased, learning ability improved, coordination and skills increased, and efficiency and ambition were demonstrated in initiation of some development projects planned and initiated following this medical intervention.
However, energy requirements also increased. Subsistence based on an once daily cassava staple was no longer adequate, and enriching dietary elements were sought with special hunger for animal fats. Ground nuts came to be in higher demand, but required more energy input in cultivation and soil improvement. More of the forest surrounding the small village was slashed and burned for increased garden plots, and people walked further for food, firewood, and water. Even in this region of sparsely settled scarce resources, there were scattered groups encroached upon by the expanding demands of the coalescing compounds in Sasaland.
And Sasaland is no longer small! Compounds have become villages and villages have become crowded. A letter sent by a chief informant announces in amazement: “It seems every woman is pregnant.” Fertility has soared, even among cretins whose anovulatory cycles had previously limited their fertility, and whose stunted stature had made delivery impossible, requiring C-section. Not only has fertility increased dramatically, but elimination of neonatal cretinism has caused the stillbirth rate to plummet. Both maternal and infant survival rates have changed dramatically from the time previous to the medical intervention when cretins were laboring to deliver cretins, often with the loss of both.
The population has doubled within the 8 y of the initiation of treatment, and the new members of this population pyramid, heavy at the base, are both quantitatively and qualitatively much better consumers.
The most readily observable change has been in the environment. What had been a series of forest clearings with scattered hut compounds have become a large confluent regional village and there is considerable degradation of what had been a typically luxuriant tropical forest ecology. 4 streams, no longer adequate, are now also polluted. Latrines had been built, but are now crowded past capacity, and children, particularly, do not use them. Agricultural intensification is unlikely because of scarce poor soils on mostly volcanic rock, now denuded of much of its forest cover through slashing both for firewood and more garden space.
[While fascinating documentation of the benefits of iodization in an extreme case, Geelhoed’s group-selectionism angle seems poorly thought-out: by his own account, cretinism & goiters are profoundly disadvantageous to individuals & their relatives, who crave any source of iodine; the fact that the treated population & fertility increased so much, without crashing, demonstrates that it could not be in any way an ‘adaptation’ (even if we supposed a long but completely invisible history of past population crashes which could impose any group selective pressure at all).]