Apperceptive agnosia
Each patient that suffers from apperceptive agnosia does not have brain damage in exactly the same area. However, brain damage in proximity to the occipital lobe is largely correlated with the patterns of deficit seen in apperceptive agnosics. For example, patient JB suffered extensive damage to the parietal-occipital areas to the left cerebral hemisphere leading to his deficit in the ability to name distinguish between structurally similar object.
Altered state of consciousness
Cannabis is a psychoactive drug that is known to alter the state of consciousness. Cannabis alters mental activity, memory, and pain perception. One who is under the influence of cannabis may (or may not) experience degrees of paranoia, increased sensitivity, and delayed reactions not normal for their usual conscious state. A 2009 review of anxiety and cannabis studies concluded that “frequent cannabis users appear to have higher levels of anxiety than non-users,” and that “a considerable number of subjects developed anxiety disorders before the first symptoms of cannabis dependence.” That led researchers to believe that anxiety-prone people tend to use cannabis as a self-prescribed anxiety medicine, opposing the idea that cannabis is what's causing the anxiety. (Frazier, 2010)