For example, studies attempting to differentiate between dementing conditions of different etiologies, such as

vascular dementia as compared with AD, have found little evidence of differential diagnostic utility from neuropsychological assessment.18 In fact, a fascinating book by Zakzanis et al19 that broadly approached this topic has suggested that for many conditions there is very little differential diagnostic information contained in a neuropsychological assessment that even allows for differentiation between healthy populations Inhibitors,research,lifescience,medical and patients with a variety of neuropsychiatric conditions. Their meta-analysis includes all of the research published on neuropsychological test differences between healthy controls and several neuropsychiatric target populations during the years 1980-1997. As a result, there is a wealth of detail on how much information each of these neuropsychological tests provides for test-based differential diagnosis of the target populations compared Inhibitors,research,lifescience,medical with healthy comparison subjects. It is important in this area to consider the differences between differential diagnosis and statistically significant differences Inhibitors,research,lifescience,medical in performance across different conditions. An effect size of .6 SD in the difference of two means, by convention a large effect and easy to detect in samples as small as 20 individuals per group, is associated with 62% overlap between the two samples. In order to be able Inhibitors,research,lifescience,medical to tell with 90% certainty

that an individual’s test score is consistent with a psychiatric or neurological diagnosis and not part

of the lower end of the distribution of healthy, an average difference of about 2.5 SD between populations is required. Many statistically significant differences between samples would fare poorly as candidates for differential Inhibitors,research,lifescience,medical diagnosis. For example, people with schizophrenia routinely have more significant cognitive deficits than people with bipolar disorder, regardless of the mood state of the bipolar patients.20 However, since bipolar patients themselves are more impaired in their cognitive performance than healthy people, there is substantial overlap in the distributions of cognitive Adenosine triphosphate performance between people with schizophrenia and bipolar disorder and minimal differential diagnostic information available. In contrast to the differences between people with AD and healthy populations on delayed recall memory, there is little discrimination between bipolar and schizophrenia populations. The distributions of patients with severe mental illness and healthy people have substantial overlap. As can be seen in Figure 1, there is considerable overlap in the distributions of scores on neuropsychological assessments of people with schizophrenia and healthy people, even if the means of the distributions are two full standard deviations apart. The r-BANS21 is an abbreviated neuropsychological assessment that examines multiple ability domains in a repeatable format.