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BACKGROUND: Autism is a syndrome of unknown cause, marked by abnormal development of social behavior. Attempts to link pathological features of the amygdala, which plays a key role in emotional processing, to autism have shown little consensus.
OBJECTIVE: To evaluate amygdala volume in individuals with autism spectrum disorders and its relationship to laboratory measures of social behavior to examine whether variations in amygdala structure relate to symptom severity.
DESIGN: We conducted 2 cross-sectional studies of amygdala volume, measured blind to diagnosis on high-resolution, anatomical magnetic resonance images. Participants were 54 males aged 8 to 25 years, including 23 with autism and 5 with Asperger syndrome or pervasive developmental disorder not otherwise specified, recruited and evaluated at an academic center for developmental disabilities and 26 age- and sex-matched community volunteers. The Autism Diagnostic Interview-Revised was used to confirm diagnoses and to validate relationships with laboratory measures of social function.
MAIN OUTCOME MEASURES: Amygdala volume, judgment of facial expressions, and eye tracking.
RESULTS: In study 1, individuals with autism who had small amygdalae were slowest to distinguish emotional from neutral expressions (P=.02) and showed least fixation of eye regions (P=.04). These same individuals were most socially impaired in early childhood, as reported on the Autism Diagnostic Interview-Revised (P<.04). Study 2 showed smaller amygdalae in individuals with autism than in control subjects (P=.03) and group differences in the relation between amygdala volume and age. Study 2 also replicated findings of more gaze avoidance and childhood impairment in participants with autism with the smallest amygdalae. Across the combined sample, severity of social deficits interacted with age to predict different patterns of amygdala development in autism (P=.047).
CONCLUSIONS: These findings best support a model of amygdala hyperactivity that could explain most volumetric findings in autism. Further psychophysiological and histopathological studies are indicated to confirm these findings.
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Mindfulness meditation is a set of attention-based, regulatory, and self-inquiry training regimes. Although the impact of mindfulness training (MT) on self-regulation is well established, the neural mechanisms supporting such plasticity are poorly understood. MT is thought to act through interoceptive salience and attentional control mechanisms, but until now conflicting evidence from behavioral and neural measures renders difficult distinguishing their respective roles. To resolve this question we conducted a fully randomized 6 week longitudinal trial of MT, explicitly controlling for cognitive and treatment effects with an active-control group. We measured behavioral metacognition and whole-brain blood oxygenation level-dependent (BOLD) signals using functional MRI during an affective Stroop task before and after intervention in healthy human subjects. Although both groups improved significantly on a response-inhibition task, only the MT group showed reduced affective Stroop conflict. Moreover, the MT group displayed greater dorsolateral prefrontal cortex responses during executive processing, consistent with increased recruitment of top-down mechanisms to resolve conflict. In contrast, we did not observe overall group-by-time interactions on negative affect-related reaction times or BOLD responses. However, only participants with the greatest amount of MT practice showed improvements in response inhibition and increased recruitment of dorsal anterior cingulate cortex, medial prefrontal cortex, and right anterior insula during negative valence processing. Our findings highlight the importance of active control in MT research, indicate unique neural mechanisms for progressive stages of mindfulness training, and suggest that optimal application of MT may differ depending on context, contrary to a one-size-fits-all approach.
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Research shows that racial discrimination results in adverse behavioral health outcomes for African–American young adults, including risk for depression, anxiety, and substance use. Although high levels of mindfulness have been shown to reduce risk for such health outcomes, it is unknown whether mindfulness can reduce risk as a consequence of racial discrimination, particularly among African Americans. Three-hundred and eighty-eight African–American young adults between the ages of 18 and 24 (M = 20.6, 62% female) completed measures assessing past-year experiences of racial discrimination, depressive symptoms, anxiety symptoms, alcohol use, and trait mindfulness. A positive correlation was found between racial discrimination and the behavioral health outcomes, as well as a negative correlation between mindfulness and the behavioral health outcomes. Moreover, mindfulness was found to significantly moderate the effect of racial discrimination on mood symptoms. Although mindfulness was found to lessen the effect of racial discrimination on alcohol use, this difference was not statistically significant. In line with previous literature, racial discrimination was shown to have a negative impact on behavioral health outcomes among African Americans. Moreover, our findings provide support for the buffering effect of mindfulness on mood symptoms as a consequence discrimination. This suggests that increasing mindfulness may be an effective strategy to include in interventions targeting improvement in mood symptoms for African–American young adults. However, alternative strategies may be more appropriate to address outcomes, such as alcohol use, as a consequence of racial discrimination.
In a world where water is everything, Sustainable Nation follows three individuals who are doing their part to bring sustainable water solutions to an increasingly thirsty planet.