From: rpattree2@gmail.com   
      
   No, Weed Won't Rot Your Brain    
      
   by Maia SzalavitzApr 17, 2014 5:45 am EDT    
   Can casual marijuana use damage the brains of young adults? A new study says   
   yes--but its participants suggest otherwise.    
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   All across the Internet, headlines are screaming Buzzkill and Marijuana Makes   
   Young Brains Go to Pot. But a new study, published in the Journal of   
   Neuroscience, does not in any way prove that casual marijuana use is bad for   
   your brain.    
      
   140416-szalavitz-weed-brain-tease    
   The Daily Beast    
   In order to understand why, all you need to do is actually read the   
   research--and be able to think a bit critically. You don't need to know   
   anything particular about fMRI or any other scary acronyms and you don't need   
   to know your amygdala from your    
   Shatner's Bassoon. You don't even need to know any statistics.    
      
   Here's the first big problem. The 20 marijuana-smoking participants, who took   
   the drug at least once a week, were deliberately selected to be healthy. If   
   they had any marijuana-related problems--or any psychiatric problems or other   
   issues--they were    
   excluded from participating.    
      
   Are you beginning to see what's wrong? Although the pot-smoking participants   
   showed brain differences in comparison to the controls who were also selected   
   to be normal--both groups were normal! If the smokers had any ma   
   ijuana-related problems or any    
   type of impairment, they would not have been included in the first place.   
   Therefore, the brain changes that the researchers found were--by   
   definition--not associated with any cognitive, emotional, or mental problems   
   or differences.    
      
   "I'm disappointed that scientists are still able to publish high-profile   
   papers that only look at neuroimaging without a behavioral endpoint," says   
   Carl Hart, an associate professor of psychology at Columbia University who was   
   not associated with the    
   research (Disclosure: he and I worked on a book project together). Hart   
   compares the findings to brain differences found between the genders. "There   
   are structural differences between men and women in certain areas," he says,   
   but they don't predict    
   differences in ability. "We don't say this means women are impaired," he adds.    
      
   The authors claim that the differences they saw could mean that these   
   participants are at risk of future problems--but we know that 35 percent of   
   young adults 18-20 have smoked marijuana in the past year, with a full 1 in 5   
   reporting smoking at least    
   once in the past month.    
      
   Once they reach age 26, however, less than 1 percent have marijuana problems   
   serious enough to be classified as addiction. What that means is that whatever   
   brain changes are seen in casual users, they don't predict addiction,   
   otherwise, all casual users    
   would become addicted--or at least, a much larger proportion than actually do.   
   We've already had several generations of American adults who survived far   
   higher rates of marijuana use than we see now--without encountering a major   
   epidemic of cognitive    
   impairment, schizophrenia, or lack of motivation.    
      
   Sadly, this isn't even the only issue with the study. "Just casual use appears   
   to create changes in the brain in areas you don't want to change," lead author   
   Hans Breiter, professor of psychiatry at Northwestern University Feinberg   
   School of Medicine,    
   told USA Today. But note that Breiter hedges by saying "appears to create,"   
   rather than "creates." That's because this type of study cannot determine   
   cause and effect: while it did show that the heavier users in the sample   
   seemed to have more extreme    
   changes than the lighter users, this does not prove that higher doses cause   
   greater brain changes. That's because pre-existing differences in people's   
   brains may lead them to use more or less marijuana-- and the scans may simply   
   be picking up on these    
   differences.    
      
   Does this imply that marijuana is completely benign and everyone should smoke   
   all day, every day? Of course not! But what it does mean is that, as we   
   consider policy changes like legalization, we need a far more skeptical and   
   intelligent press. Marijuana    
   itself may or may not impair cognition-- but discussions of marijuana policy   
   clearly do so, in a way that is detrimental to our political health.    
      
      
      
      
   http://www.thedailybeast.com/articles/2014/04/17/no-weed-won-t-r   
   t-your-brain.html    
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)