Disgust sensitivity relates to attitudes toward gay men and lesbian women across 31 nations

Previous work has reported a relation between pathogen-avoidance motivations and prejudice toward various social groups, including gay men and lesbian women. It is currently unknown whether this association is present across cultures, or specific to North America. Analyses of survey data from adult heterosexuals ( N = 11,200) from 31 countries showed a small relation between pathogen disgust sensitivity (an individual-difference measure of pathogen-avoidance motivations) and measures of antigay attitudes. Analyses also showed that pathogen disgust sensitivity relates not only to antipathy toward gay men and lesbians, but also to negativity toward other groups, in particular those associated with violations of traditional sexual norms (e.g., prostitutes). These results suggest that the association between pathogen-avoidance motivations and antigay attitudes is relatively stable across cultures and is a manifestation of a more general relation between pathogen-avoidance motivations and prejudice towards groups associated with sexual norm violations.

The prevalence of dyads in social life

A salient objective feature of the social environment in which people find themselves is group size. Knowledge of group size is highly relevant to behavioural scientists given that humans spend considerable time in social settings and the number of others influences much of human behaviour. What size of group do people actually look for and encounter in everyday life? Here we report four survey studies and one experience-sampling study (total N = 4,398) which provide evidence for the predominance of the dyad in daily life. Relative to larger group sizes, dyads are most common across a wide range of activities (e.g., conversations, projects, holidays, movies, sports, bars) obtained from three time moments (past activities, present, and future activities), sampling both mixed-sex and same-sex groups, with three different methodological approaches (retrospective reports, real-time data capture, and preference measures) in the United States and the Netherlands. We offer four mechanisms that may help explain this finding: reciprocity, coordination, social exclusion, and reproduction. The present findings advance our understanding of how individuals organize themselves in everyday life.

Bridging psychology and engineering to make technology work for people

Engineering grand challenges and big ideas not only demand innovative engineering solutions, but also typically involve and affect human thought, behavior, and quality of life. To solve these types of complex problems, multidisciplinary teams must bring together experts in engineering and psychological science, yet fusing these distinct areas can be difficult. This article describes how Human Systems Engineering (HSE) researchers have confronted such challenges at the interface of humans and technological systems. Two narrative cases are reported-computer game-based cognitive assessments and medical device reprocessing-and lessons learned are shared. The article then discusses 2 strategies currently being explored to enact such lessons and enhance these kinds of multidisciplinary engineering teams: a "top-down" administrative approach that supports team formation and productivity through a university research center, and a "bottom-up" engineering education approach that prepares students to work at the intersection of psychology and engineering. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Facial gender interferes with decisions about facial expressions of anger and happiness

The confounded signal hypothesis maintains that facial expressions of anger and happiness, in order to more efficiently communicate threat or nurturance, evolved forms that take advantage of older gender recognition systems, which were already attuned to similar affordances. Two unexplored consequences of this hypothesis are (1) facial gender should automatically interfere with discriminations of anger and happiness, and (2) controlled attentional processes (like working memory) may be able to override the interference of these particular expressions on gender discrimination. These issues were explored by administering a Garner interference task along with a working memory task as an index of controlled attention. Results show that those with good attentional control were able to eliminate interference of expression on gender decisions but not the interference of gender on expression decisions. Trials in which the stimulus attributes were systematically correlated also revealed strategic facilitation for participants high in attentional control. (PsycINFO Database Record

Dynamical Evolutionary Psychology: Mapping the Domains of the New Interactionist Paradigm

Dynamical systems and evolutionary theories have both been proposed as integrative approaches to psychology. These approaches are typically applied to different sets of questions. Dynamical systems models address the properties of psychological systems as they emerge and change over time; evolutionary models address the specific functions and contents of psychological structures. New insights can be achieved by integrating these two paradigms, and we propose a framework to begin doing so. The framework specifies a set of six evolutionarily fundamental social goals that place predictable constraints on emergent processes within and between individuals, influencing their dynamics over the short-term, and across developmental and evolutionary time scales. These social goals also predictably influence the dynamic emergence and change of cultural norms. This framework has heuristic as well as integrative potential, generating novel hypotheses within a number of unexplored areas atpsychology's interface with the other biological and social sciences.

Concentrating on Beauty: Sexual Selection and Sociospatial Memory

In three experiments, location memory for faces was examined using a computer version of the matching game Concentration. Findings suggested that physical attractiveness led to more efficient matching for female faces but not for male faces. Study 3 revealed this interaction despite allowing participants to initially see, attend to, and match the attractive male faces in the first few turns. Analysis of matching errors suggested that, compared to other targets, attractive women were less confusable with one another. Results are discussed in terms of the different functions that attractiveness serves for men and women.

They All Look the Same to Me (Unless They're Angry)

People often find it more difficult to distinguish ethnic out-group members compared with ethnic in-group members. A functional approach to social cognition suggests that this bias may be eliminated when out-group members display threatening facial expressions. In the present study, 192 White participants viewed Black and White faces displaying either neutral or angry expressions and later attempted to identify previously seen faces. Recognition accuracy for neutral faces showed the out-group homogeneity bias, but this bias was entirely eliminated for angry Black faces. Indeed, when participants' cognitive processing capacity was constrained, recognition accuracy was greater for angry Black faces than for angry White faces, demonstrating an out-group heterogeneity bias.

Out of Sight but Not Out of Mind: Memory Scanning is Attuned to Threatening Faces

Working memory (WM) theoretically affords the ability to privilege social threats and opportunities over other more mundane information, but few experiments have sought support for this contention. Using a functional logic, we predicted that threatening faces are likely to elicit encoding benefits in WM. Critically, however, threat depends on both the capacities and inclinations of the potential aggressor and the possible responses available to the perceiver. Two experiments demonstrate that participants more efficiently scan memory for angry facial expressions, but only when the faces also bear other cues that are heuristically associated with threat: masculinity in Study 1 and outgroup status in Study 2. Moreover, male participants showed robust speed and accuracy benefits, whereas female participants showed somewhat weaker effects, and only when threat was clearly expressed. Overall results indicate that working memory for faces depends on the accessibility of self-protective goals and on the functional relevance of other social attributes of the face.

Out of sight but not out of mind: memory scanning is attuned to threatening faces

Working memory (WM) theoretically affords the ability to privilege social threats and opportunities over other more mundane information, but few experiments have sought support for this contention. Using a functional logic, we predicted that threatening faces are likely to elicit encoding benefits in WM. Critically, however, threat depends on both the capacities and inclinations of the potential aggressor and the possible responses available to the perceiver. Two experiments demonstrate that participants more efficiently scan memory for angry facial expressions, but only when the faces also bear other cues that are heuristically associated with threat: masculinity in Study 1 and outgroup status in Study 2. Moreover, male participants showed robust speed and accuracy benefits, whereas female participants showed somewhat weaker effects, and only when threat was clearly expressed. Overall results indicate that working memory for faces depends on the accessibility of self-protective goals and on the functional relevance of other social attributes of the face.

The Vividness of the Happy Face

An emerging literature reveals that happy faces are vivid: They automatically and rapidly engage cognitive processing at many different levels. They do this in part because their form has evolved to take advantage of preexisting efficiencies in visual perception. In addition to “happy advantages” at the earliest stages of perception, perceivers add their own benefits, with both attentional and memory mechanisms appearing to favor happy faces. These effects exist because for humans, prosocial communication is critical. Coevolution has sculpted both the signaler and the receiver to enhance the efficiency of this communication as a way to undergird our highly social nature.

A reproductive threat-based model of evolved sex differences in jealousy

Although heterosexual women and men consistently demonstrate sex differences in jealousy, these differences disappear among lesbians and gay men as well as among heterosexual women and men contemplating same-sex infidelities (infidelities in which the partner and rival are the same sex). Synthesizing these past findings, the present paper offers a reproductive threat-based model of evolved sex differences in jealousy that predicts that the sexes will differ only when the jealous perceivers' reproductive outcomes are differentially at risk. This model is supported by data from a web-based study in which lesbians, gay men, bisexual women and men, and heterosexual women and men responded to a hypothetical infidelity scenario with the sex of the rival randomly determined. After reading the scenario, participants indicated which type of infidelity (sexual versus emotional) would cause greater distress. Consistent with predictions, heterosexual women and men showed a sex difference when contemplating opposite-sex infidelities but not when contemplating same-sex infidelities, whereas lesbians and gay men showed no sex difference regardless of whether the infidelity was opposite-sex or same-sex.

A Reproductive Threat-Based Model of Evolved Sex Differences in Jealousy

Although heterosexual women and men consistently demonstrate sex differences in jealousy, these differences disappear among lesbians and gay men as well as among heterosexual women and men contemplating same-sex infidelities (infidelities in which the partner and rival are the same sex). Synthesizing these past findings, the present paper offers a reproductive threat-based model of evolved sex differences in jealousy that predicts that the sexes will differ only when the jealous perceivers' reproductive outcomes are differentially at risk. This model is supported by data from a web-based study in which lesbians, gay men, bisexual women and men, and heterosexual women and men responded to a hypothetical infidelity scenario with the sex of the rival randomly determined. After reading the scenario, participants indicated which type of infidelity (sexual versus emotional) would cause greater distress. Consistent with predictions, heterosexual women and men showed a sex difference when contemplating opposite-sex infidelities but not when contemplating same-sex infidelities, whereas lesbians and gay men showed no sex difference regardless of whether the infidelity was opposite-sex or same-sex.

Who Expressed What Emotion? Men Grab Anger, Women Grab Happiness

When anger or happiness flashes on a face in the crowd, do we misperceive that emotion as belonging to someone else? Two studies found that misperception of apparent emotional expressions - "illusory conjunctions" - depended on the gender of the target: male faces tended to "grab" anger from neighboring faces, and female faces tended to grab happiness. Importantly, the evidence did not suggest that this effect was due to the general tendency to misperceive male or female faces as angry or happy, but instead indicated a more subtle interaction of expectations and early visual processes. This suggests a novel aspect of affordance-management in human perception, whereby cues to threat, when they appear, are attributed to those with the greatest capability of doing harm, whereas cues to friendship are attributed to those with the greatest likelihood of providing affiliation opportunities.

Signal detection on the battlefield: priming self-protection vs. revenge-mindedness differentially modulates the detection of enemies and allies

Detecting signs that someone is a member of a hostile outgroup can depend on very subtle cues. How do ecology-relevant motivational states affect such detections? This research investigated the detection of briefly-presented enemy (versus friend) insignias after participants were primed to be self-protective or revenge-minded. Despite being told to ignore the objectively nondiagnostic cues of ethnicity (Arab vs. Western/European), gender, and facial expressions of the targets, both priming manipulations enhanced biases to see Arab males as enemies. They also reduced the ability to detect ingroup enemies, even when these faces displayed angry expressions. These motivations had very different effects on accuracy, however, with self-protection enhancing overall accuracy and revenge-mindedness reducing it. These methods demonstrate the importance of considering how signal detection tasks that occur in motivationally-charged environments depart from results obtained in conventionally motivationally-inert laboratory settings.

Self-protective biases in group categorization: threat cues shape the psychological boundary between "us" and "them"

Across 6 studies, factors signaling potential vulnerability to harm produced a bias toward outgroup categorization--a tendency to categorize unfamiliar others as members of an outgroup rather than as members of one's ingroup. Studies 1 through 4 demonstrated that White participants were more likely to categorize targets as Black (as opposed to White) when those targets displayed cues heuristically associated with threat (masculinity, movement toward the perceiver, and facial expressions of anger). In Study 5, White participants who felt chronically vulnerable to interpersonal threats responded to a fear manipulation by categorizing threatening (angry) faces as Black rather than White. Study 6 extended these findings to a minimal group paradigm, in which participants who felt chronically vulnerable to interpersonal threats categorized threatening (masculine) targets as outgroup members. Together, findings indicate that ecologically relevant threat cues within both the target and the perceiver interact to bias the way people initially parse the social world into ingroup vs. outgroup. Findings support a threat-based framework for intergroup psychology.

I only have eyes for you: Ovulation redirects attention (but not memory) to attractive men

A number of studies have found a disjunction between women's attention to, and memory for, handsome men. Although women pay initial attention to handsome men, they do not remember those men later. The present study examines how ovulation might differentially affect these attentional and memory processes. We found that women near ovulation increased their visual attention to attractive men. However, this increased visual attention did not translate into better memory. Discussion focuses on possible explanations, in the context of an emerging body of findings on disjunctions between attention to, and memory for, other people.

More Memory Bang for the Attentional Buck: Self-Protection Goals Enhance Encoding Efficiency for Potentially Threatening Males

When encountering individuals with a potential inclination to harm them, people face a dilemma: Staring at them provides useful information about their intentions but may also be perceived by them as intrusive and challenging-thereby increasing the likelihood of the very threat the people fear. One solution to this dilemma would be an enhanced ability to efficiently encode such individuals-to be able to remember them without spending any additional direct attention on them. In two experiments, the authors primed self-protective concerns in perceivers and assessed visual attention and recognition memory for a variety of faces. Consistent with hypotheses, self-protective participants (relative to control participants) exhibited enhanced encoding efficiency (i.e., greater memory not predicated on any enhancement of visual attention) for Black and Arab male faces-groups stereotyped as being potentially dangerous-but not for female or White male faces. Results suggest that encoding efficiency depends on the functional relevance of the social information people encounter.

Goal-Driven Cognition and Functional Behavior: The Fundamental-Motives Framework

Fundamental motives have direct implications for evolutionary fitness and orchestrate attention, memory, and social inference in functionally specific ways. Motivational states linked to self-protection and mating offer illustrative examples. When self-protective motives are aroused, people show enhanced attention to, and memory for, angry male strangers; they also perceive out-group members as especially dangerous. In contrast, when mating motives are aroused, men show enhanced attention to and memory for attractive members of the opposite sex; mating motives also lead men (but not women) to perceive sexual arousal in attractive members of the opposite sex. There are further functionally specific consequences for social behavior. For example, self-protective motives increase conformity among both men and women, whereas mating motives lead men (but not women) to engage in anticonformist behavior. Other motivational systems trigger different adaptive patterns of cognitive and behavioral responses. This body of research illustrates the highly specific consequences of fitness-relevant motivational states for cognition and behavior, and highlights the value of studying human motivation and cognition within an evolutionary framework.

Infection breeds reticence: the effects of disease salience on self-perceptions of personality and behavioral avoidance tendencies

Social living brings humans great rewards, but also associated dangers, such as increased risk of infection from others. Although the body's immune system is integral to combating disease, it is physiologically costly. Less costly are evolved mechanisms for promoting avoidance of people who are potentially infectious, such as perceiving oneself as less social and increasing the tendency to make avoidant movements. In Experiment 1, exposure to a disease prime led participants to rate themselves as less extraverted than did exposure to a control prime, and led participants high in perceived vulnerability to disease (PVD) to rate themselves as less agreeable and less open to experience than did exposure to a control prime. In Experiment 2, a disease prime facilitated avoidant tendencies in arm movements when participants viewed photographs of faces, especially for participants high in PVD. Together, these findings reveal functional changes in perception and behavior that would serve to promote avoidance of potentially infectious individuals.

Following in the wake of anger: when not discriminating is discriminating

Does seeing a scowling face change your impression of the next person you see? Does this depend on the race of the two people? Across four studies, White participants evaluated neutrally expressive White males as less threatening when they followed angry (relative to neutral) White faces; Black males were not judged as less threatening following angry Black faces. This lack of threat-anchored contrast for Black male faces is not attributable to a general tendency for White targets to homogenize Black males-neutral Black targets following smiling Black faces were contrasted away from them and seen as less friendly-and emerged only for perceivers low in motivation to respond without prejudice (i.e., for those relatively comfortable responding prejudicially). This research provides novel evidence for the overperception of threat in Black males.

A pox on the mind: Disjunction of attention and memory in the processing of physical disfigurement

The unfavorable treatment of people with physical disfigurements is well-documented, yet little is known about basic perceptual and cognitive responses to disfigurement. Here, we identify a specialized pattern of cognitive processing consistent with the hypothesis that disfigurements act as heuristic cues to contagious disease. Disfigurements are often invariant across time and difficult to conceal, and thus observers can detect the presence of such cues without necessarily remembering the particular individuals bearing these cues. Indeed, despite the fact that disfigured faces were especially likely to hold disease-sensitive perceivers' attention (Study 1), disfigured individuals were often confused with one another and thus not well remembered later (Study 2), revealing a disjunction of the typical relationship between elevated attention and elevated memory. We discuss the implications of our results for stigmatization of people with and without physical abnormalities and suggest the possibility that cognitive mechanisms for processing social information may be functionally tuned to the variant nature of important cues.

The confounded nature of angry men and happy women

Findings of 7 studies suggested that decisions about the sex of a face and the emotional expressions of anger or happiness are not independent: Participants were faster and more accurate at detecting angry expressions on male faces and at detecting happy expressions on female faces. These findings were robust across different stimulus sets and judgment tasks and indicated bottom-up perceptual processes rather than just top-down conceptually driven ones. Results from additional studies in which neutrally expressive faces were used suggested that the connections between masculine features and angry expressions and between feminine features and happy expressions might be a property of the sexual dimorphism of the face itself and not merely a result of gender stereotypes biasing the perception.

Perception and recognition memory of words and werds: two-way mirror effects

We examined associative priming of words (e.g., TOAD) and pseudohomophones of those words (e.g., TODE) in lexical decision. In addition to word frequency effects, reliable base-word frequency effects were observed for pseudohomophones: Those based on high-frequency words elicited faster and more accurate correct rejections. Associative priming had disparate effects on high- and low-frequency items. Whereas priming improved performance to high-frequency pseudohomophones, it impaired performance to low-frequency pseudohomophones. The results suggested a resonance process, wherein phonologic identity and semantic priming combine to undermine the veridical perception of infrequent items. We tested this hypothesis in another experiment by administering a surprise recognition memory test after lexical decision. When asked to identify words that were spelled correctly during lexical decision, the participants often misremembered pseudohomophones as correctly spelled items. Patterns of false memory, however, were jointly affected by base-word frequencies and their original responses during lexical decision. Taken together, the results are consistent with resonance accounts of word recognition, wherein bottom-up and top-down information sources coalesce into correct, and sometimes illusory, perception. The results are also consistent with a recent lexical decision model, REM-LD, that emphasizes memory retrieval and top-down matching processes in lexical decision.

Functional projection: how fundamental social motives can bias interpersonal perception

Results from 2 experimental studies suggest that self-protection and mate-search goals lead to the perception of functionally relevant emotional expressions in goal-relevant social targets. Activating a self-protection goal led participants to perceive greater anger in Black male faces (Study 1) and Arab faces (Study 2), both out-groups heuristically associated with physical threat. In Study 2, participants' level of implicit Arab-threat associations moderated this bias. Activating a mate-search goal led male, but not female, participants to perceive more sexual arousal in attractive opposite-sex targets (Study 1). Activating these goals did not influence perceptions of goal-irrelevant targets. Additionally, participants with chronic self-protective and mate-search goals exhibited similar biases. Findings are consistent with a functionalist, motivation-based account of interpersonal perception.

Sexually Selective Cognition: Beauty Captures the Mind of the Beholder

Across 5 experimental studies, the authors explore selective processing biases for physically attractive others. The findings suggest that (a). both male and female observers selectively attend to physically attractive female targets, (b). limiting the attentional capacity of either gender results in biased frequency estimates of attractive females, (c). although females selectively attend to attractive males, limiting females' attentional capacity does not lead to biased estimates of attractive males, (d). observers of both genders exhibit enhanced recognition memory for attractive females but attenuated recognition for attractive males. Results suggest that different mating-related motives may guide the selective processing of attractive men and women.

Effects of time of administration and dietary iodine levels on potassium iodide (KI) blockade of thyroid irradiation by 131I from radioactive fallout

Radioiodines, particularly 131I, may be released into the environment in breach-of-containment nuclear reactor accidents and localize in and irradiate the thyroid with an attendant risk of neoplastic growth and other adverse health effects. Pharmacologic thyroid blockade by oral potassium iodide (KI) (50-100 mg in adults) can substantially reduce thyroid uptake of and irradiation by internalized radioiodine. In the current analysis, computer modeling of iodine metabolism has been used to systematically elucidate the effects of two practically important but highly variable factors on the radioprotective effect of KI: the time of administration relative to exposure to radioiodine and the dietary level of iodine. In euthyroid adults receiving iodine-sufficient diets (250 microg d(-1) in the current analysis), KI administered up to 48 h before 131I exposure can almost completely block thyroid uptake and therefore greatly reduce the thyroid absorbed dose. However, KI administration 96 h or more before 131I exposure has no significant protective effect. In contrast, KI administration after exposure to radioiodine induces a smaller and rapidly decreasing blockade effect. KI administration 16 h or later after 131I exposure will have little effect on thyroid uptake and absorbed dose and therefore little or no protective effect. The 131I thyroid absorbed dose is two-fold greater with insufficient levels of dietary iodine, 2,900 cGy/37 MBq, than with sufficient levels of dietary iodine, 1,500 cGy/37 MBq. When KI is administered 48 h or less before 131I intake, the thyroid absorbed doses (in cGy/37 MBq) are comparably low with both sufficient and insufficient dietary iodine levels. When KI is administered after 131I intake, however, the protective effect of KI is less and decreases more rapidly with insufficient than with sufficient dietary iodine. For example, KI administration 2 and 8 h after 131I intake yields protective effects of 80 and 40%, respectively, with iodine-sufficient diets, but only 65 and 15% with iodine-deficient diets. In conclusion, whether exposed populations receive sufficient or insufficient dietary iodine, oral KI is an effective means of reducing thyroid irradiation from environmentally dispersed radioiodine but is effective only when administered within 2 d before to approximately 8 h after radioiodine intake.

The Chernobyl accident and its consequences: update at the millennium

A marked increase in the incidence of papillary thyroid cancer in children has been documented in regions of the former Soviet Union most heavily contaminated by radioactive fallout from the Chernobyl nuclear power plant accident in April 1986. Accumulation of radioactive iodines by normal iodine trapping mechanisms resulted in significant radiation doses to the thyroid gland. Although it has long been known that thyroidal radiation resulted in nuclear and chromosomal abnormalities visible by light microscopy, modern molecular biology techniques are beginning to identify much smaller alterations in chromosomal coding sequences that are associated with malignant transformation. Although stable chromosomal abnormalities can be detected in Chernobyl-associated thyroid cancers, they are much less prevalent than in thyroid cancers developing after external beam irradiation. However, several unique chromosomal breakpoints have been described in radiation-associated thyroid cancers that are not commonly found in spontaneously occurring thyroid cancer. Furthermore, activation of specific subtypes of the ret/PTC tyrosine kinase oncogene appears to be more common in radiation-associated thyroid cancers than in spontaneous thyroid cancers. In summary, thyroid cancers developing in the aftermath of the Chernobyl accident provide a unique opportunity to search for chromosomal abnormalities that may be specific for radiation-induced thyroid cancer.

A comparison of recombinant human thyrotropin and thyroid hormone withdrawal for the detection of thyroid remnant or cancer

Recombinant human TSH has been developed to facilitate monitoring for thyroid carcinoma recurrence or persistence without the attendant morbidity of hypothyroidism seen after thyroid hormone withdrawal. The objectives of this study were to compare the effect of administered recombinant human TSH with thyroid hormone withdrawal on the results of radioiodine whole body scanning (WBS) and serum thyroglobulin (Tg) levels. Two hundred and twenty-nine adult patients with differentiated thyroid cancer requiring radioiodine WBS were studied. Radioiodine WBS and serum Tg measurements were performed after administration of recombinant human TSH and again after thyroid hormone withdrawal in each patient. Radioiodine whole body scans were concordant between the recombinant TSH-stimulated and thyroid hormone withdrawal phases in 195 of 220 (89%) patients. Of the discordant scans, 8 (4%) had superior scans after recombinant human TSH administration, and 17 (8%) had superior scans after thyroid hormone withdrawal (P = 0.108). Based on a serum Tg level of 2 ng/mL or more, thyroid tissue or cancer was detected during thyroid hormone therapy in 22%, after recombinant human TSH stimulation in 52%, and after thyroid hormone withdrawal in 56% of patients with disease or tissue limited to the thyroid bed and in 80%, 100%, and 100% of patients, respectively, with metastatic disease. A combination of radioiodine WBS and serum Tg after recombinant human TSH stimulation detected thyroid tissue or cancer in 93% of patients with disease or tissue limited to the thyroid bed and 100% of patients with metastatic disease. In conclusion, recombinant human TSH administration is a safe and effective means of stimulating radioiodine uptake and serum Tg levels in patients undergoing evaluation for thyroid cancer persistence and recurrence.

Evaluation of environmental, nutritional, and host factors in cats with hyperthyroidism

The pathologic changes associated with hyperthyroidism (adenomatous hyperplasia, adenoma of the thyroid gland) have been well characterized in cats, but the pathogenesis of these changes remains unclear. In this research, we undertook a case-control study to search for potential risk factors for this disease. Owners of 379 hyperthyroid and 351 control cats were questioned about their cats' exposure to potential risk factors including breed, demographic factors, medical history, indoor environment, chemicals applied to the cat and environment, and diet. The association between these hypothesized risk factors and outcome of disease was evaluated by conditional logistic regression. Two genetically related cat breeds (ie, Siamese and Himalayan) were found to have diminished risk of developing hyperthyroidism. Cats that used litter had higher risk of developing hyperthyroidism than those that did not. Use of topical ectoparasite preparations was associated with increased risk of developing hyperthyroidism. Compared with cats that did not eat canned food, those that ate commercially prepared canned food had an approximate 2-fold increase in risk of disease. When these 4 variables (breed, use of cat litter, consumption of canned cat food, and use of topical ectoparasite preparations) from the univariate analysis were selected for further study as candidate risk factors and analyzed by multivariate conditional logistic regression, a persistent protective effect of breed (ie, Siamese or Himalayan) was found. In addition, results suggested a 2- to 3-fold increase in risk of developing hyperthyroidism among cats eating a diet composed mostly of canned cat food and a 3-fold increase in risk among those using cat litter. In contrast, the use of commercial flea products did not retain a strong association. The results of this study indicate that further research into dietary and other potentially important environmental factors (eg, cat litter) is warranted.

Thyroid uptake of liquid versus capsule 131I tracers in hyperthyroid patients treated with liquid 131I

The amount of 131I used to treat hyperthyroid patients is based in part on the 24-hour thyroid uptake of a diagnostic amount of radioiodine (tracer). We compared the 24-hour uptake of an 131I tracer administered in liquid or capsule form to the 24-hour uptake of 131I therapy administered as liquid. Sixty-five hyperthyroid patients with Graves' disease were evaluated and subsequently treated with radioiodine. The liquid group (45 patients) received a liquid 131I tracer (1.85 MBq [0.05 mCi]) and the capsule group (20 patients) received a capsule 131I tracer (1.63 MBq [0.044 mCi]). Probe calibration factors were the same for the liquid and capsule 131I standards. All patients received therapeutic amounts of 131I [114.7-1106.3 MBq [3.1-29.9 mCi]) in liquid form. Therapy uptakes were obtained using the same collimated uptake probe modified with a calibrated lead shield to attenuate the high photon flux. The mean therapeutic uptake was the same for both groups (58%). The mean diagnostic uptake for the capsule group, however, was less than the mean diagnostic uptake for the liquid group (44% vs. 63%). The mean diagnostic uptake for the capsule group was significantly lower than the mean therapeutic uptake for this group (44% vs. 58%), whereas the mean diagnostic and therapeutic uptakes were similar for the group receiving a liquid tracer (63% vs. 58%). In conclusion, diagnostic uptakes performed with a liquid tracer more accurately predicted liquid therapy uptakes than diagnostic uptakes performed with a capsule tracer. This raises concern about the bioavailability of 131I in capsule form and has implications for determining the amount of 131I to administer for therapy. Patients whose 131I therapy was based on the uptake of a capsule tracer received a higher than intended amount of radiation to the thyroid gland.

Cancer mortality following treatment for adult hyperthyroidism. Cooperative Thyrotoxicosis Therapy Follow-up Study Group

CONTEXT

High-dose iodine 131 is the treatment of choice in the United States for most adults with hyperthyroid disease. Although there is little evidence to link therapeutic (131)I to the development of cancer, its extensive medical use indicates the need for additional evaluation.

OBJECTIVE

To evaluate cancer mortality among hyperthyroid patients, particularly after (131)I treatment.

DESIGN

A retrospective cohort study.

SETTING

Twenty-five clinics in the United States and 1 clinic in England.

PATIENTS

A total of 35 593 hyperthyroid patients treated between 1946 and 1964 in the original Cooperative Thyrotoxicosis Therapy Follow-up Study; 91 % had Graves disease, 79% were female, and 65% were treated with (131)I.

MAIN OUTCOME MEASURE

Standardized cancer mortality ratios (SMRs) after 3 treatment modalities for hyperthyroidism.

RESULTS

Of the study cohort, 50.5% had died by the end of follow-up in December 1990. The total number of cancer deaths was close to that expected based on mortality rates in the general population (2950 vs 2857.6), but there was a small excess of mortality from cancers of the lung, breast, kidney, and thyroid, and a deficit of deaths from cancers of the uterus and the prostate gland. Patients with toxic nodular goiter had an SMR of 1.16 (95% confidence interval [CI], 1.03-1.30). More than 1 year after treatment, an increased risk of cancer mortality was seen among patients treated exclusively with antithyroid drugs (SMR, 1.31; 95% CI, 1.06-1.60). Radioactive iodine was not linked to total cancer deaths (SMR, 1.02; 95% CI, 0.98-1.07) or to any specific cancer with the exception of thyroid cancer (SMR, 3.94; 95% CI, 2.52-5.86).

CONCLUSIONS

Neither hyperthyroidism nor (131)I treatment resulted in a significantly increased risk of total cancer mortality. While there was an elevated risk of thyroid cancer mortality following (131)I treatment, in absolute terms the excess number of deaths was small, and the underlying thyroid disease appeared to play a role. Overall, (131)I appears to be a safe therapy for hyperthyroidism.

Potassium iodide for thyroid blockade in a reactor accident: administrative policies that govern its use

A marked increase in thyroid cancer among young children who were in the vicinity of the Chernobyl nuclear power plant at the time of the 1986 accident strongly suggests a possible causal relationship to the large amounts of radioactive iodine isotopes in the resulting fallout. Although remaining indoors, restricting consumption of locally produced milk and foodstuffs, and evacuation are important strategies in a major breach-of-containment accident, stable potassium iodide (KI) prophylaxis given shortly before or immediately after exposure can reduce greatly the thyroidal accumulation of radioiodines and the resulting radiation dose. Concerns about possible side effects of large-scale, medically unsupervised KI consumption largely have been allayed in light of the favorable experience in Poland following the Chernobyl accident; 16 million persons received single administrations of KI with only rare occurrence of side effects and with a probable 40% reduction in projected thyroid radiation dose. Despite the universal acceptance of KI as an effective thyroid protective agent, supplies of KI in the US are not available for public distribution in the event of a reactor accident largely because government agencies have argued that stockpiling and distribution of KI to other than emergency workers cannot be recommended in light of difficult distribution logistics, problematic administrative issue, and a calculated low cost-effectiveness. However, KI in tablet form is expensive and has a long shelf life, and many countries have largely stockpiles and distribution programs. The World Health Organization recognizes the benefits of stable KI and urges its general availability. At present there are 110 operating nuclear power plants in the US and more than 300 in the rest of the world. These reactors product 17% of the world's electricity and in some countries up to 60-70% of the total electrical energy. Almost all US nuclear power plants have multistage containment structures with large steel and concrete shells and multiple redundancy of core cooling mechanisms. These successfully prevented the release of major amounts of radionuclides in the Three Mile Island partial loss-of-primary coolant accident in 1979. The Chernobyl accident, in a different type of reactor that is common in Eastern Europe, did not have effective outer shell containment and released almost 50 MCi of 131I compared to the 20 Ci of 131I released at Three Mile Island. Such accidents have precipitated extensive re-evaluation of the design and safety devices of all operating reactors. However, a major contributing factor to the accidents was human error and considerable efforts must be made to train plant operators so they have a better understanding of reactor operation and use of safety mechanisms.

Radioiodine and the treatment of hyperthyroidism: the early history

Little was known about iodine metabolism in the mid-1930s, but when Saul Hertz and his chief, J. Howard Means, at the Massachusetts General Hospital (MGH) realized in 1936 that radioiodine could be made and used as a tracer, they arranged with physicists Robley Evans and Arthur Roberts at the Massachusetts Institute of Technology (MIT) to make the short-lived 128I and study its physiology in rabbits. By 1938, they showed that the rabbit's thyroid gland rapidly took up 128I, especially when there was only a little non-radioactive iodine present. There was, however, no hope of using 128I as a treatment because of its brief half-life (25 minutes). In 1939, Joseph Hamilton and Mayo Soley, working with Ernest Lawrence's cyclotron in Berkeley, California, were able to make several radioiodines; one was 130I (12-hour half-life) and another 131I (8-day half-life). They were the first to give these radioiodines to humans to study iodine physiology. The MGH-MIT group also built a cyclotron and by 1940 had generated these two new radioiodines. One of the goals of both groups was the treatment of hyperthyroidism. Hertz and Roberts were the first to do so on March 31, 1941; Hamilton and John Lawrence, Ernest's brother, began on October 12, 1941. By 1942, the United States was actively fighting in World War II. That year both Boston and Berkeley groups have preliminary data on the treatment of hyperthyroidism in Atlantic City; both showed that it was effective and went on to treat more patients. In Berkeley the therapy was viewed cautiously, and, in many case, the physicists were mainly occupied with work for the Manhattan District. In Boston Hertz used the therapy as often as he could, emphasizing the use of 130I, until he joined the U.S. Navy in 1943. Earle Chapman, a clinician on the voluntary staff of the MGH, took over Hertz's practice in 1943; their later differences over the precise treatment and who was in charge led to their falling out. After Hertz's release from the Navy he was not permitted to return to the MGH and became quite bitter; Chapman stayed on at the MGH. After the war was over, both had acquired a sufficient number of patients--there was then no such thing as a controlled trial--and wrote up the results for publication. Each wrote a different physicist, Hertz with Roberts and Chapman with Evans. When Hertz learned that Chapman's paper was being considered by the Journal of the American Medical Associations, he quickly sent his manuscript to JAMA as well. Although the editor of JAMA was puzzled by two papers on the same topic from the same institution, both papers appeared in the same issue of JAMA on May 11, 1964, and announced the new therapy was effective treatment for hyperthyroidism.

Radioiodine and thyroid disease: the beginning

In 1936, Karl Compton, then president of the Massachusetts Institute of Technology (MIT) and the thyroid group of the Massachusetts General Hospital (MGH), undertook a joint study that led to the production of small amounts of short-lived radioiodine (iodine 128, half-life, 25 min). The original intent was to use it for diagnosis and treatment of thyroid disease, but in order to explore the underlying physiology, their first work was performed in rabbits and published in 1938. It clearly showed that the radioiodine was selectively and avidly taken up by the thyroid gland. It was immediately apparent to the MGH-MIT group and another team working at the Berkeley, CA cyclotron that longer-lasting iodine isotopes were needed, and soon both developed procedures for cyclotron-produced 130 (half-life, 12.5 hr) and 131I (half-life, 8 d). In 1939, the Berkeley group, using 131I, was the first to show that the normal human thyroid gland accumulated radioiodine. By 1941, the MGH-MIT team, using mainly 130I, was able to successfully treat a few patients with hyperthyroidism, and so achieved their original goal. The Berkeley group did the same a few months later, using mainly 131I. Both presented results at the same meeting of the American Society for Clinical Investigation in Atlantic City, NJ in the spring of 1942. This was in the midst of World War II and it was not easy to get much 130I or 131I, so experience was limited. Although effective, radioiodine treatment of hyperthyroidism had not been widely adopted by the end of the war in 1945, partly because radioiodine remained in short supply and partly because another medical therapy for hyperthyroidism, antithyroid drugs, had been invented. However, by 1946, fission-derived radioiodine became readily available as a by-product of the Manhattan project in Oak Ridge, TN; hundreds of patients were treated within a few years, both for hyperthyroidism and for thyroid cancer. A new treatment, based on the physiological application of a radioisotope of iodine, was then a reality.

Radioiodine treatment of 524 cats with hyperthyroidism

OBJECTIVE

To evaluate a protocol for subcutaneous radioiodine treatment of cats with hyperthyroidism in which the dose was determined on the basis of severity of the cat's clinical signs, thyroid tumor size, and magnitude of the serum thyroxine (T4) concentration.

DESIGN

Prospective case series.

ANIMALS

524 cats with hyperthyroidism.

PROCEDURE

A scoring system based on 3 factors (severity of clinical signs, size of the thyroid gland, and magnitude of the serum T4 concentration) was used to select the dose of radioiodine to be administered subcutaneously.

RESULTS

On the basis of the scoring system, 310 (59%) cats were treated with a low dose of radioiodine (< 3.5 mCi; median, 3.0 mCi), 158 (30%) were treated with a moderate dose (3.5 to 4.4 mCi; median, 4.0 mCi), and 56 (11%) were treated with a high dose (> or = 4.5 mCi; median, 5.0 mCi). At time of discharge from the hospital, serum T4 concentration was still high in 80 (15.3%) cats, but by 6 months after administration of radioiodine, the serum T4 concentration had decreased to within or below reference range in all but 8 (1.5%) cats with persistent hyperthyroidism. Many cats had low serum T4 concentrations at some time after radioiodine treatment, but only 11 (2.1%) cats developed clinical and clinicopathologic features of hypothyroidism and required supplementation with L-thyroxine. Thirteen (2.5%) cats had a relapse of hyperthyroidism 1.1 to 6.5 years after initial radioiodine treatment. Overall, the response to treatment was considered good in 94.2% of the cats. Median survival time in the cats was 2.0 years; the percentage of cats alive after 1, 2, and 3 years of treatment was 89, 72, and 52%, respectively.

CLINICAL IMPLICATIONS

Results of the study suggest that this method of dose estimation works well and that subcutaneous administration of radioiodine provides a safe and effective means of treating hyperthyroidism in cats.

Treatment of hyperthyroid disease

PURPOSE

To evaluate treatments for hyperthyroid disease.

DATA SOURCES

Selected studies published during the last 20 years addressing the diagnosis, causes, and treatment of hyperthyroid disease.

STUDY SELECTION

Studies were chosen based on their usefulness in addressing specific points in the treatment of hyperthyroid disease.

DATA EXTRACTION

Various treatment principles extracted from the references form the basis for the conclusions and recommendations made here.

RESULTS

Hyperthyroid disease is a common endocrine disease. Although Graves disease is the most common cause of thyrotoxicosis, other primary and secondary causes exist. With classic signs and symptoms accompanied by confirmatory laboratory measures of thyroid hyperfunction, the diagnosis can be established firmly. Radioiodine is the preferred method to treat Graves disease; however, recent data concerning treatment with a combination of propylthiouracil and thyroxine require further evaluation to establish its efficacy. Radioiodine is also the preferred treatment for the other forms of hyperthyroid disease; however, patient-specific considerations in both may require patient-tailored therapies.

CONCLUSIONS

Hyperthyroid disease can be treated definitively for most patients. Palliative therapy with beta-adrenergic blockade is useful in some patients. Further studies are needed to determine whether more recently described treatments have improved efficacy and whether therapy directed specifically at the underlying immunologic cause of Graves disease can be used successfully.

Radon update: facts concerning environmental radon: levels, mitigation strategies, dosimetry, effects and guidelines. SNM Committee on Radiobiological Effects of Ionizing Radiation

The risk from environmental radon levels is not higher now than in the past, when residential exposures were not considered to be a significant health hazard. The majority of the radon dose is not from radon itself, but from short-lived alpha-emitting radon daughters, most notably 218Po(T1/2 3 min) and 214Po (T1/2 0.164 msec) along with beta particles from 214Bi (T1/2 19.7 min). Radon gas can penetrate homes from many sources and in various fashions. Measuring radon in homes is simple and relatively inexpensive and may be accomplished in a variety of ways. Although it is not possible to radon-proof a house, it is possible to reduce the level. In high radon areas, if the average level is higher than 4-8 pCi/liter (NCRP recommended level is 8 pCi/liter; EPA recommended level is 4 pCi/liter), appropriate action is advised. The shape of the dose response curves for miners exposed to alpha-emitting particles in the workplace is consistent with current biologic knowledge. It is linear in the low dose range and saturates in the high dose range. No detectable increase in lung cancer frequency is seen in the lowest exposed miners (those with exposures < 120 WLM, the relevant dose interval for most homes). Evidence for a health effect from radon exposure is based on data from animal studies and epidemiologic studies of mines. Extensive radiobiologic data predict a linear dose-response curve in the low dose region due to poor biological repair mechanisms for the high density of ionizing events that alpha particles create. However, no compelling evidence for increased cancer risks has yet been demonstrated from "acceptable" levels (< 4-8 pCi/liter).

Autonomous growth and function of cultured thyroid follicles from cats with spontaneous hyperthyroidism

Spontaneous feline hyperthyroidism is a unique experimental model of toxic nodular goiter. To determine whether feline toxic goiter is caused by extrathyroidal stimulating factors or by the intrinsic autonomy of follicular cells, primary cultures of enzymatically dissociated follicles from 15 hyperthyroid cat goiters and from 3 normal cat thyroid glands were embedded in collagen gels. Growth and function in chemically defined media were assessed by autoradiography after double labeling with 3H-thymidine and 131I-Na. Iodine organification in follicles from normal glands was TSH dependent, but intense radioiodine organification occurred in follicles from hyperfunctioning goiters even in the absence of TSH. Similarly, twice as many follicular cells of hyperfunctioning thyroid tissue, maintained without TSH in the medium, were labeled after exposure to 3H-thymidine than in follicles from normal glands. The results strongly suggest that intrinsic alterations of cell function lead to autonomy of follicular growth and function and subsequently to the development of hyperplastic nodules, causing thyrotoxicosis. The reason for the focal nature of the disease remains an unresolved challenge. Further investigation using this model may further understanding of the growth of autonomous endocrine tumors.

Comparison of technetium-99m and iodine-123 imaging of thyroid nodules: correlation with pathologic findings

Three hundred and sixteen patients with solitary or dominant thyroid nodules were imaged both with technetium-99m- (99mTc) pertechnetate and iodine-123 (123I). The images were preferred, but differences were small and in 27%-58% of the cases there was no difference in quality between the two radionuclides. Discrepancies between 99mTc and 123I images were found in 5%-8% of cases, twice as often in multinodular goiters as in single nodules. Cytologic/histologic examination was performed on all nodules but no correlation was found between the pathology and the type of discrepancy. Twelve carcinomas were found (4%) but none in nodules showing a discrepancy. There was great variation among the observers about the preference for radionuclides and about the existence or type of discrepancies. The slightly better overall quality of 123I scans is probably not of diagnostic significance and does not justify the routine use of 123I instead of 99mTc. Routine reimaging of 99mTc hot nodules with radioiodine for cancer detection does not appear to be necessary.

Radioactive iodine treatment of a functional thyroid carcinoma producing hyperthyroidism in a dog

Radioactive iodine (131I) was used in the treatment of a 12-year-old female dog with hyperthyroidism resulting from a large, unresectable (and metastatic) thyroid carcinoma associated with signs of severe inspiratory stridor and dyspnea. Hyperthyroidism was diagnosed on the basis of clinical signs (polyuria, polydipsia, polyphagia, weight loss, nervousness) and high basal serum thyroxine (T4) concentrations, as well as thyroid radioiodine kinetic studies that showed a high radioiodine uptake into the thyroid (% thyroid uptake) and markedly increased serum concentrations of protein-bound iodine-131 (PB131I) after 131I tracer injection. Thyroid imaging revealed diffuse radionuclide accumulation by the tumor, which involved both thyroid lobes. The dog was treated with three large doses of radioiodine (131I), ranging from 60 to 75 mCi, given at intervals of 5 to 7 months. The dog became euthyroid, and the size of the tumor decreased by approximately 25% after each 131I treatment, improving the severe inspiratory stridor and dyspnea, but both the hyperthyroid state and breathing difficulty recurred within a few months of each treatment. The dog was euthanatized 5 months after the last treatment because of progressive tracheal compression and pulmonary metastasis.

Reactor accidents. Public health strategies and their medical implications

In a reactor accident with release of radioactivity, the major potential public health risks are likely to result from radioiodines, particularly iodine 131, which can be readily volatilized and dispersed. They are rapidly absorbed and concentrated by the thyroid, which could result in substantial thyroidal radiation. Although some forms of radiation can cause thyroid cancer in humans, 131I has not been shown to do so, and 40 years of safe experience with this radionuclide in routine clinical thyroid testing and treatment has been reassuring. Nevertheless, since 131I has been shown to cause thyroid neoplasms in animals, efforts to minimize unwarranted exposure seem advisable. Potassium iodide, administered at an appropriate time, will effectively block thyroid uptake, but it has potential toxicity and may be difficult to distribute effectively and safely on a large scale in an emergency. Evaluation of the risks and benefits of potassium iodide use is essential to establishing sound public health policy but awaits additional scientific information.