If you are smoking Regs/Swag/Imported Beasters that have been covered in pesticides and other chemicals to preserve their growth - you are going to get a lot of different results than subjects who used Top Shelf Medical Cannabis from a dispensary. Stay away from low quality cannabis if you economically can... seriously..
If you were smoking top end SFV OG Kush or Bubba Kush I doubt you would be able to really be in much of a state of depression or lack of enjoyment in the day.
Sure if you had some of the worst PTSD ever, it may not fully bring you back - but those high euphoria / anti-depression cannabis strains are not going to bring you deeper into a depressive funk. Hell, they have been shown time and time again to essentially fully treat PTSD on many cases of veterans and severe cases...
Poorly Grown cannabis will not be helpful in modulating the natural cannabinoids in our body - just like incorrectly synthesized prescriptions are going to give you different effects, many more in the negative direction. And anyone who has popped 10+ seeds knows that some phenos just are not good buzzes or counterproductive sometimes to the effect you want - while other strains/phenos will have exactly the psychoactive effects one seeks.
These studies you post assume that THC is synonymous (Identical) with Cannabis (Which is not true) Cannabis's effects are a result of the ratio of the different cannabinoids in each strain/grow and goes well beyond the one area they are looking at in these studies you posted which is THC. It would be comparable to scientist studying the brain by only looking at "Dopamine" and ignoring "Serotonin, norepinephrine and the many other neurotransmitters". This is the opposite of scientific method and rational thinking in terms of looking at the evidence - if they purposely choose to ignore all cannabinoids but THC when discussing cannabis.
Just wanted to clear this up cannabis doesn't damage the brain or cognitive abilities (see below) =) Also if you are looking for a motivation high smoke a sativa or sativa dominant hybrid and stay away from over-mature (Flowered too long) and overly-potent pure indicas in the morning. Some indica dominants are fine in the morning if you have a nice tolerance and strong determination for the activities of the day.
Heavy Marijuana Use Doesn't Damage Brain:
Analysis of Studies Finds Little Effect From Long-Term Use
Full Article @ http://www.webmd.com/mental-health/n...t-damage-brain
The researchers found only a "very small" impairment in memory and learning among long-term marijuana users. Otherwise, scores on thinking tests were similar to those who don't smoke marijuana, according to a new analysis of 15 previous studies.
In those studies, some 700 regular marijuana users were compared with 484 non-users on various aspects of brain function -- including reaction time, language and motor skills, reasoning ability, memory, and the ability to learn new information.
"We were somewhat surprised by our finding, especially since there's been a controversy for some years on whether long-term cannabis use causes brain damage," says lead researcher and psychiatrist Igor Grant, MD.
"I suppose we expected to see some differences in people who were heavy users, but in fact the differences were very minimal."
(Continued in Full Article @ http://www.webmd.com/mental-health/n...t-damage-brain)