This study revealed the lesions in many regions of the brain of ketamine addicts. These lesions appeared as minute patches in the first year and became larger sites of atrophy by 4 years of addiction. The majority of the addicts was on dosage of 1 g per day and used ketamine daily for several years. In this work, since the volunteers were mostly below 30 years old and only 2 individuals above 30 years old, a comparison of the effect of age upon addiction was not conclusive in this stage, even though we had seen no worse in the aged group (above 30 years old) when compared with the slightly younger old. A study of age response would definitely be conducted in future. However, it is well-known that ketamine addicts were usually young as represented in this cohort. The brain regions affected were prefrontal, parietal, occipital, limbic, brainstem, and corpus striatum. The lesions affected both the gray and white matter, i.e., neurons and nerve fibers in the human; these were similar to those reported earlier by us in the mice and the monkey (Yu et al.,
2012). This MRI study also collated with the work by Morgan and Curran suggesting a loss of memory via psychological examination in chronic ketamine abuses (Morgan and Curran,
2006). In animals, prefrontal cortex apoptosis, mutated tau aggregation, brainstem chemical changes, and cerebellar apoptosis had been reported (Mak et al.,
2010; Yeung et al.,
2010b; Sun et al.,
2011,
2012; Tan et al.,
2011b,
2012; Yu et al.,
2012; Wai et al.,
2013). In fact, in the mice model, it had been documented both neurons and fibers (white matter) were both targets like in this report consisting of human subjects (Mak et al.,
2010; Yeung et al.,
2010b). Along with structural changes, fMRI and functional studies confirmed functional and cognitive derangements (Morgan and Curran,
2006; Sun et al.,
2011,
2012; Chan et al.,
2012; Yu et al.,
2012). This human MRI brain imaging on the ketamine addicts thus consolidated that the areas of lesion in mice, monkey, and human were essentially similar. We now have clear and unequivocal proof of damages in the CNS upon chronic use of ketamine in human
) but I still love me some dissos, although it's been over a year now. 