Numerous other studies have shown cannabis is beneficial in combating Alzheimer and that it is active in prohibiting the growth of toxic amyloid plagues on the brain that are part of the disease.  This article, like most that are anxious to portray cannabis as bad, leaves out a lot of facts. How much was blood flow reduced?  Was it enough to cause damage?  Did any of the subjects exhibit symptoms that could be contributed to reduced blood flow?  How much cannabis did the subjects smoke and for how long?  The answer is they don't know because its a statistical study using tests that were NOT made for the purpose of studying cannabis. Notice there is no mention of who sponsored the study. This is not science, its propaganda.