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【medical-news】关注青少年焦虑
Craske and her colleagues are finding that neuroticism — the tendency to experience negative emotions such as fear, anxiety, guilt, shame, sadness or anger — is a powerful predictor of both anxiety and depression. Newly published research from the long-term study highlights a potential mechanism by which neuroticism confers risk. The researchers report that teenagers who are high in neuroticism appear to become unnecessarily anxious in ways that are out of proportion with actual circumstances.
As part of the study, the students were placed in front of computers and told that when the screen became red and said "Danger," they might receive as many as three small muscle shocks, each one stronger than the last. A countdown bar indicated when the shock was coming; as the bar counted down, the screen became redder. The students were also told that when the screen was green and said "Safe," they would receive no shock.
They then saw eight green and eight red screens, in random order, while researchers used sensors to study their physiological reactions, such as the "startle reflex," which is measured by eye blinks, heart rate and sweat gland activity. (Each participant actually received only one mild shock, during the fourth red screen.)
All participants showed an elevated startle response when the threat of shock was most imminent, during the final countdown on the danger screens; this is the time at which the fear response is most imperative to survival. However, those teenagers high in neuroticism showed a stronger startle response under conditions when the shock was not imminent and, in particular, during sections of the safe screens and the early phase of the danger screens.
"This is interpreted as neuroticism leading to enhanced anxiety under conditions associated with aversive events but in which negative events themselves are very unlikely," Craske said. "It may represent a failure to distinguish conditions that are safe from conditions in which threatening events are very likely to occur. By translation, these findings suggest that persons with high neuroticism would respond with appropriate fear to actual threatening events, but with additional unnecessary anxiety to surrounding conditions. This type of responding may explain why neuroticism contributes to the development of pervasive anxiety."
Craske and her colleagues report their findings this month in the journal Biological Psychiatry.
She hopes the study will reveal the risk factors that predict anxiety, versus depression, and which risk factors are common to both anxiety and depression.
"Anxiety and depression often go hand in hand; we're trying to learn what factors place adolescents at risk for the development of anxiety and depression, what is common between anxiety and depression, and what is unique to each," Craske said. "We chose this age group because 16-to-19 is when anxiety and mood disorders tend to surge in prevalence."
Some 25 percent of the U.S. population experience anxiety disorders over their lifetime; these disorders are about twice as common in women as men, Craske said. If those at risk can be identified in advance, perhaps they can be treated with an early intervention, reducing the risk for later anxiety problems.
At the outset of the study, many of the teenagers were already experiencing depression and anxiety, more than Craske had expected.
"We assumed most would not be currently anxious or depressed and we would see who develops disorders over time," she said. "We were surprised to see that more than 20 percent had a current or past anxiety disorder, and 30 percent had a current or past mood disorder at the start of the study. As a result, we switched from solely evaluating risk factors for the onset of anxiety and mood disorders to include evaluation of risk factors for the persistence of anxiety and depression over time. We want to assess for whom do these disorders become more severe over time and why."
Every 12 months, the researchers conduct a comprehensive evaluation, and every six months, the adolescents complete self-report questionnaires. Craske is the study's principal investigator at UCLA, and UCLA psychology professor Constance Hammen is a co-investigator. The study is also being conducted at Northwestern University, where the principal investigators are psychology professors Richard Zinbarg and Susan Mineka.
Co-authors on the new research include Edward Ornitz, professor of psychiatry and biobehavioral sciences at the Semel Institute for Neuroscience and Human Behavior at UCLA, and Bruce Naliboff, also of the Semel Institute and co-director of the UCLA–Veterans Affairs Center for Neurobiology of Stress.
The longitudinal study marks the first time physiological, cognitive and personality measures, along with life stressors, have been analyzed together, Craske said.
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作者:admin@医学,生命科学 2010-11-05 17:11
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