Marijuana Use In Pregnancy Damages Kids’ Learning

Children born to mothers who use marijuana during pregnancy may suffer a host of lasting mental defects, suggests a new study in rats. Marijuana is the most widely used illegal drug among women of reproductive age.

The offspring of pregnant rats given a low dose of cannabinoid were found to perform poorly in learning tests throughout their lives, compared to rats that were not exposed.

The research found long-term learning in the rats was damaged by the cannabinoids irreversibly disrupting chemical and electrical processes in the brain during gestation. The exposed rats were also more hyperactive as infants, although this effect wore off as the rats reached adulthood.

The possible effects of maternal marijuana use on the unborn child and the child’s later behaviour are controversial. Rat studies can be very useful in assessing human effects, because studies of people can be hampered by complex confounding factors which could include cigarette smoking, wealth or urban living.

In the study, pregnant rats were injected with a low dose of an artificial cannabinoid. Offspring exposed to the drug during gestation showed hyperactivity during infancy and adolescence, as measured by how many times they broke infrared beams crisscrossing their cages. This stopped when they reached adulthood, but was replaced by problems with memory retention.

The research showed reduced levels of a messenger chemical called glutamate in the hippocampus. Exposure to marijuana during pregnancy also has a strong effect on visual mapping and analysis in human children.

Category:       Health
Source:          Adapted from: New Scientist,  March 25, 2003
Words:          250

妊娠期服用大麻会损害孩子的学习能力

 一份研究老鼠的新报告表明，由服用大麻的孕妇所生育的孩子有可能患有多种永久性智力缺陷。大麻是育龄妇女最普遍服用的非法毒品。

 研究人员发现，由注射了小剂量大麻成分的妊娠鼠所生育的鼠崽，与没有接触过大麻的鼠崽相比，在它们一生的学习能力测试中表现很差。

 该研究发现，老鼠的长期学习能力受到大麻成分的损害，因为在老鼠妊娠期间大麻成分使大脑的化学过程与电子过程产生不可逆的中断。接触过大麻的老鼠在幼儿期也相对过于活跃，尽管这种影响随着它们进入成年期而逐渐消失。

 孕妇服用大麻对未出生婴儿以及婴儿出生后的行为可能造成的影响是个有争议的问题。对老鼠的研究在评估大麻对人类的影响方面可能很有用处，因为对人的研究会受到复杂的令人困惑的因素所限制，其中可能包括吸烟、财富或城市生活。

 在研究过程中，研究人员将一小剂量人工合成的大麻成分注射到妊娠鼠身上。在母体内接触到毒品的鼠崽在幼儿期和青春期表现异常活跃，这一情况是通过测算他们穿过纵横交叉于笼子的红外线光束的次数而得到证实的。当这些老鼠进入成年期时，这种异常活跃的情况就停止了，取而代之的是记忆力出现问题。

 此项研究表明，一种被称为谷氨酸盐的信使化学成分在海马里的含量有所减少。妊娠期间接触大麻对于儿童的视觉映像与视觉分析也有极大的影响。