The Kraepelinian dichotomy is made questionable by grey matter abnormalities in bipolar and schizophrenia; schizophrenia is distinguishable from bipolar in that regions of grey matter reduction are generally larger in magnitude, although adjusting for gender differences reduces the difference to the left dorsomedial prefrontal cortex, and right dorsolateral prefrontal cortex.During attentional tasks, first episode psychosis is associated with hypoactivation in the right middle frontal gyrus, a region generally described as encompassing the dorsolateral prefrontal cortex (dlPFC). In congruence with studies on grey matter volume, hypoactivity in the right insula, and right inferior parietal lobe is also reported. During cognitive tasks, hypoactivities in the right insula, dACC, and the left precuneus, as well as reduced deactivations in the right basal ganglia, right thalamus, right inferior frontal and left precentral gyri are observed. These results are highly consistent and replicable possibly except the abnormalities of the right inferior frontal gyrus. Decreased grey matter volume in conjunction with bilateral hypoactivity is observed in anterior insula, dorsal medial frontal cortex, and dorsal ACC. Decreased grey matter volume and bilateral hyperactivity is reported in posterior insula, ventral medial frontal cortex, and ventral ACC. Hallucinations
Studies during acute experiences of hallucinations demonstrate increased activity in primary or secondary sensory cortices. As auditory hallucinations are most common in psychosis, most robust evidence exists for increased activity in the left middle temporal gyrus, left superior temporal gyrus, and left inferior frontal gyrus (i.e. Brocas area).
The expense of such treatment is unwarranted and may divert resources from evidence-based treatment. Critics claim that the symptoms of those with Scotopic Sensitivity Syndrome are related to already known visual perceptual and neurological disorders. According to a statement released by the American Optometric Association in 2004:
There is evidence that the underlying symptoms associated with specifically Meares Irlen Syndrome, are related to identifiable vision anomalies, e.g., accommodative, binocular, and ocular motor dysfunctions, in many patients seeking help from coloured lenses. Furthermore, such conditions return to normal function when appropriately treated with lenses, prisms, or vision therapy. When patients exhibiting Meares Irlen Syndrome were treated with vision therapy, their symptoms were relieved. These patients were no longer classified as exhibiting this syndrome, and therefore did not demonstrate a need for the coloured overlays or tinted lenses. As outlined by Hyatt, Stephenson and Carter (2009):
In 1990, the Journal of Learning Disabilities published a special issue that provided intensive coverage of Irlen lenses. In the preface to the issue, the editor in chief, Wiederholt, noted that each of the studies had serious theoretical, medical/physical, and methodological flaws, but were published along with articles critiquing the studies to provide readers with an overview of the Irlen procedures as well as guidance for conducting quality research studies. He, along with Hoyt (1990), Parker (1990), and Solan (1990), noted that these initial studies by Blaskey et al. (1990), OConnor, Sofo, Kendall, and Olsen (1990), and Robinson and Conway (1990) failed to support the treatment validity of colored overlays.