Behavioral adjustment moderates the effect of neuroticism on brain volume relative to intracranial volume.

OBJECTIVE: The present study examined whether the effect of neuroticism on brain structure is moderated by behavioral adjustment. BACKGROUND: Neuroticism is widely thought to be harmful to health. However, recent work using proinflammatory biomarkers showed that this effect depends on behavioral adjustment, the willingness and ability to adjust and cope with environmental contingencies, such as different opinions of others or unpredictable life situations. Here, we sought to extend this observation to "brain health" by testing total brain volume (TBV). METHOD: Using a community sample of 125 Americans, we examined structural magnetic resonance imaging of the brain and quantified TBV. We tested whether the effect of neuroticism on TBV was moderated by behavioral adjustment, net of intracranial volume, age, sex, educational achievement, and race. RESULTS: Behavioral adjustment significantly moderated the effect of neuroticism on TBV, such that neuroticism was associated with lower TBV only when behavioral adjustment was low. There was no such effect when behavioral adjustment was high. CONCLUSION: The present findings suggest that neuroticism is not debilitating to those who constructively cope with stress. Implications are further discussed.

Going beyond heritability: Mechanisms of gene-culture coevolution.

The target article offers an important cautionary note on the interpretation of the heritability index. However, it does not directly address how culture and genes might interact. Here, we suggest that one allele of the dopamine D4 receptor gene promotes the acquisition of cultural values and practices and likely has coevolved with the human culture over the last 50,000 years.

Racial residential segregation and economic disparity jointly exacerbate COVID-19 fatality in large American cities.

The disproportionately high rates of both infections and deaths among racial and ethnic minorities (especially Blacks and Hispanics) in the United States during the COVID-19 pandemic are consistent with the conclusion that structural inequality can produce lethal consequences. However, the nature of this structural inequality in relation to COVID-19 is poorly understood. Here, we hypothesized that two structural features, racial residential segregation and income inequality, of metropolitan areas in the United States have contributed to health-compromising conditions, which, in turn, have increased COVID-19 fatalities; moreover, that these two features, when combined, may be particularly lethal. To test this hypothesis, we examined the growth rate of confirmed COVID-19 cases and deaths in an early 30-day period of the outbreak in the counties located in each of the 100 largest metropolitan areas in the United States. The growth curves for cases and deaths were steeper in counties located in metropolitan areas where Blacks and Hispanics are residentially segregated from Whites. Moreover, the effect of racial residential segregation was augmented by income inequality within each county. These data strongly suggest that racial and economic disparities have caused a greater death toll during the current pandemic. We draw policy implications for making virus-resilient cities free from such consequences.

Interdependent self-construal predicts increased gray matter volume of scene processing regions in the brain.

Interdependent self-construal (SC) is thought to lead to a more holistic cognitive style that emphasizes the processing of the background scene of a focal object. At present, little is known about whether the structural properties of the brain might underlie this functional relationship. Here, we examined the gray matter (GM) volume of three cortical regions involved in scene processing -- a cornerstone of contextual processing. Study 1 tested 78 European American non-student adults and found that interdependent (vs. independent) SC predicts higher GM volume in the parahippocampal place area (PPA), one of the three target regions. Testing both European American and East Asian college students (total N = 126), Study 2 replicated this association. Moreover, the GM volume of all the three target regions was greater for East Asians than for European Americans. Our findings suggest that there is a structural neural underpinning for the cultural variation in cognitive style.

Does facial action modulate neural responses of emotion? An examination with the late positive potential (LPP).

The facial feedback hypothesis suggests that emotional facial action causally modulates the subjective experience of emotion. Notably, some proposed that facial action modulates emotional experience because it directly modulates neural responses of emotion. At present, the robustness of the facial feedback hypothesis has been debated. Moreover, little evidence exists for the direct modulation of neural responses by facial action. To fill these gaps, we tested whether facial action systematically modulates a well-validated electrocortical signature of emotional arousal, the late positive potential. Fifty-seven young adults rated the pleasantness of 180 pictures from the international affective picture system while holding chopsticks differently in their mouth to mimic either smiling or frowning expression. Their electroencephalogram was monitored. It was found that the frowning expression increased the late positive potential for negative pictures. In contrast, the smiling expression had no significant effect. Pleasantness ratings were also consistent with the facial feedback hypothesis. We concluded that the facial feedback effect is weak but robust. Critically, we presented the first evidence that facial action modulates an emotion-related neural response. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Relational Mobility Predicts Faster Spread of COVID-19: A 39-Country Study.

It has become increasingly clear that COVID-19 is transmitted between individuals. It stands to reason that the spread of the virus depends on sociocultural ecologies that facilitate or inhibit social contact. In particular, the community-level tendency to engage with strangers and freely choose friends, called relational mobility, creates increased opportunities to interact with a larger and more variable range of other people. It may therefore be associated with a faster spread of infectious diseases, including COVID-19. Here, we tested this possibility by analyzing growth curves of confirmed cases of and deaths due to COVID-19 in the first 30 days of the outbreaks in 39 countries. We found that growth was significantly accelerated as a function of a country-wise measure of relational mobility. This relationship was robust either with or without a set of control variables, including demographic variables, reporting bias, testing availability, and cultural dimensions of individualism, tightness, and government efficiency. Policy implications are also discussed.

Mandated Bacillus Calmette-Guérin (BCG) vaccination predicts flattened curves for the spread of COVID-19.

Bacillus Calmette-Guérin (BCG) vaccination may reduce the risk of a range of infectious diseases, and if so, it could protect against coronavirus disease 2019 (COVID-19). Here, we compared countries that mandated BCG vaccination until at least 2000 with countries that did not. To minimize any systematic effects of reporting biases, we analyzed the rate of the day-by-day increase in both confirmed cases (134 countries) and deaths (135 countries) in the first 30-day period of country-wise outbreaks. The 30-day window was adjusted to begin at the country-wise onset of the pandemic. Linear mixed models revealed a significant effect of mandated BCG policies on the growth rate of both cases and deaths after controlling for median age, gross domestic product per capita, population density, population size, net migration rate, and various cultural dimensions (e.g., individualism). Our analysis suggests that mandated BCG vaccination can be effective in the fight against COVID-19.

The gray matter volume of the temporoparietal junction varies across cultures: a moderating role of the dopamine D4 receptor gene (DRD4).

Prior work shows that compared to European Americans, East Asians show an enhanced propensity to take the perspective of another person. In the current work, we tested whether this cultural difference might be reflected in the gray matter (GM) volume of the temporoparietal junction (TPJ), a brain region selectively implicated in perspective taking and mentalizing. We also explored whether the cultural difference in the TPJ GM volume might be moderated by dopamine D4 receptor gene (DRD4) exon 3 variable-number tandem repeat polymorphism. Structural magnetic resonance imaging of 66 European Americans and 66 East Asian-born Asians were subjected to voxel-based morphometry. It was observed that the GM volume of the right TPJ was greater among East Asians than among European Americans. Moreover, this cultural difference was significantly more pronounced among carriers of the 7- or 2-repeat allele of DRD4 than among the non-carriers of these alleles. Our findings contribute to the growing evidence that culture can shape the brain.

Cultural variation in the gray matter volume of the prefrontal cortex is moderated by the dopamine D4 receptor gene (DRD4).

Recent evidence suggests a systematic cultural difference in the volume/thickness of prefrontal regions of the brain. However, origins of this difference remain unclear. Here, we addressed this gap by adopting a unique genetic approach. People who carry the 7- or 2-repeat (7/2-R) allele of the dopamine D4 receptor gene (DRD4) are more sensitive to environmental influences, including cultural influences. Therefore, if the difference in brain structure is due to cultural influences, it should be moderated by DRD4. We recruited 132 young adults (both European Americans and Asian-born East Asians). Voxel-based morphometry showed that gray matter (GM) volume of the medial prefrontal cortex and the orbitofrontal cortex was significantly greater among European Americans than among East Asians. Moreover, the difference in GM volume was significantly more pronounced among carriers of the 7/2-R allele of DRD4 than among non-carriers. This pattern was robust in an alternative measure assessing cortical thickness. A further exploratory analysis showed that among East Asian carriers, the number of years spent in the U.S. predicted increased GM volume in the orbitofrontal cortex. The present evidence is consistent with a view that culture shapes the brain by mobilizing epigenetic pathways that are gradually established through socialization and enculturation.

APOE-ε4 associates with hippocampal volume, learning, and memory across the spectrum of Alzheimer's disease and dementia with Lewy bodies.

INTRODUCTION: Although the apolipoprotein E ε4-allele (APOE-ε4) is a susceptibility factor for Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), its relationship with imaging and cognitive measures across the AD/DLB spectrum remains unexplored. METHODS: We studied 298 patients (AD = 250, DLB = 48; 38 autopsy-confirmed; NCT01800214) using neuropsychological testing, volumetric magnetic resonance imaging, and APOE genotyping to investigate the association of APOE-ε4 with hippocampal volume and learning/memory phenotypes, irrespective of diagnosis. RESULTS: Across the AD/DLB spectrum: (1) hippocampal volumes were smaller with increasing APOE-ε4 dosage (no genotype × diagnosis interaction observed), (2) learning performance as assessed by total recall scores was associated with hippocampal volumes only among APOE-ε4 carriers, and (3) APOE-ε4 carriers performed worse on long-delay free word recall. DISCUSSION: These findings provide evidence that APOE-ε4 is linked to hippocampal atrophy and learning/memory phenotypes across the AD/DLB spectrum, which could be useful as biomarkers of disease progression in therapeutic trials of mixed disease.