Lesson29 Alcohol Damage to the Young Brain
Few teens seem to worry about what alcohol does to their bodies. Cirrhosis of the liver is unlikely to catch up with them for decades, and heart disease must seem as remote as retirement, but recent research indicates that the younger the brain, the more it may be at risk. Because their brains are still developing, teens who drink excessively may be destroying some of their mental capacity - affecting their ability to learn.
Nearly 7 million youths between the ages of 12 and 20 binge drink at least once a month, according to the U.S. Substance Abuse and Mental Health Services Administration. That means downing five or more drinks in a row.
Teen drinkers appear to be most susceptible to damage in two developing parts of the brain, the hippocampus, a structure responsible for learning and memory, and the prefrontal cortex, the chief decision-maker and voice of reason.
In a study of how alcohol affects the hippocampus, scholars dosed adolescent and adult rats with alcohol and ran them through mazes. Compared with the adults, the adolescents failed miserably. To see whether similar results held true for humans, some scholars split a small group of volunteers into two groups: ages 21 to 24, and 25 to 29.
After drinking enough to achieve a blood-alcohol level slightly below 0.08 percent, the younger group's learning was significantly more impaired than the older group's.
cirrhosis [医]硬化
susceptible 易受影响的
hippocampus 海马状突起
prefrontal [解]额叶前部的
cortex 脑皮层
impair 削弱
酒精对青少年大脑的伤害
青少年似乎并不担心酒精对他们身体的伤害。几十年内他们不大可能会得肝硬化，心脏病对他们来讲如同退休一样遥远。但是最近的研究表明大脑越年轻，越容易受到伤害。因为青少年的大脑还在发育，过度饮酒可能会损害他们的智力&&影响他们的学习能力。
美国管制药品滥用及精神卫生管理局的数据表明，将近700万12到20岁之间的青少年每个月至少有一次过量饮酒，也就是连续喝酒五杯或五杯以上。
青少年饮酒者的大脑的两个正在发育的部分最容易受到伤害，它们是负责学习和记忆的海马状突起和主要的决策和理性中心&&前额皮质。
在一个研究酒精对海马状突起的影响的实验中，研究者给幼年的和成年的老鼠服用了酒精后把它们放到了迷宫里。与成年老鼠相比，幼年的老鼠惨败。为了验证在人类身上是否也会有相似的结果，一些研究者把一小群志愿者分成了两组，21至24年龄组和25至29年龄组。
给他们饮酒使他们血液内的酒精含量达到略低于0.08%的水平后，年龄稍小的那一组的学习能力受到的损害明显大于年龄大的那一组。 |