Dope eats grey cells

Long-term heavy users of marijuana perform significantly worse on tests of mental agility and physical dexterity than short-term users or nonusers, even when they have abstained from smoking for more than 24 hours, new research shows. Scientists, led by Lambros Messinis, a neuropsychologist at University Hospital in Petras, Greece, tested three groups.

They were 20 long-term users who had smoked four or more marijuana cigarettes a week for at least 10 years, 20 short-term users who had smoked a similar amount for 5 to 10 years and, finally, 24 people, representing a control group, who had used marijuana no more than 20 times in their lives and not in the prior two years. The long- and short-term users were drawn from participants in a drug rehabilitation programme. Even after controlling for IQ, other drug use, age, sex, depression and other variables, long-term users scored significantly lower than control group members and shorter-term users on tests of verbal fluency, memory and coordination. The exercises included naming objects when shown pictures of them, thinking up words with the same initial letter, listening to lists of words and later recalling them and drawing lines in the proper order among numbers and letters randomly spread on paper. The study appears in the March issue of Neurology. Dr Messinis acknowledged that the results might have differed with marijuana users from the general population. Still, he said, the study was carefully controlled, and frequent heavy use appeared to have significant negative effects on performance.

NYT

Sing like a bird, hear like a bat
Not only can a rare Chinese frog sing like a bird, it can also apparently hear like a bat, according to new research. Albert Feng of the University of Illinois at Urbana-Champaign and colleagues previously reported that male torrent frogs that live in an area west of Shanghai produced calls that were remarkably similar to bird songs. In a new study, published in Thursday8217;s issue of Nature, Feng and his colleagues determined that the creatures also communicate with one another through high-frequency ultrasonic calls, which previously only bats, marine mammals and some rodents were known to use. Feng and his colleagues recorded the frogs8217; audible and ultrasonic calls and then studied how eight other males responded to them, finding that most of them responded to calls in both the audible and ultrasonic ranges. They speculated the frogs evolved the ability so they could hear each other above the sound of waterfalls and other noise in their mountainous habitat. 8216;8216;Nature has a way of evolving mechanisms to facilitate communication in very adverse situations,8217;8217; Feng said. 8216;8216;One of the ways is to shift the frequencies beyond the spectrum of the background noise. Mammals such as bats, whales and dolphins do this and use ultrasound for their sonar system and communication. Frogs were never taken into consideration for being able to do this.8217;8217;

LAT-WP