Thanks Mike- I thought that the study sounded a little "too good to be true" but without knowing enough about MRI it was difficulty to provide a proper critique. Your comments were very helpful in my understanding of the limits of their study.
-Don. ----- Original Message ----- From: "Mike Wiliams" <jmicha5...@aol.com> To: "Teaching in the Psychological Sciences (TIPS)" <tips@fsulist.frostburg.edu> Sent: Saturday, December 8, 2012 11:09:22 PM Subject: Re:[tips] MRI Diagnosis Two features of the study seem fishy. The first is the manual designations of individual brain areas. Although they studied the reliability of the designations and appeared very careful, there must be some persistent error in defining the brain areas. The second is that people making these designations may have a systematic bias in the brain areas they think are associated with various disorders. This is different than being blind to the subject diagnosis. We did something similar in a study that required designating the hippocampus. I noticed that each person on the team had a different idea of where the hippocampus ended and the parahippocampus began. There were other uncertain areas. Each rater just had to make a decision. However, if the raters in this study systematically sampled more of the hippocampus for the depression group and less for the schizophrenia group then the classifications might represent such a systematic difference. Since they did not use a normalized method common across all the subjects, this could have happened and they should have examined it. The second is the high rate of classification compared to the reliabilities of the diagnostic methods. The SCID reliability varies from approx .6 to .9, depending on the diagnosis. Presumably their classification rates should be lower, given the error in making anatomical designations and measurements and the error in making diagnoses. The extremely high rates of classification suggest that some systematic bias is linking the brain measurements to the diagnostic clusters. Finally, these overly empirical and descriptive studies do not enlighten us concerning how the brain mediates these disorders. Mike Williams Assaf, B., Mohamed, F. B., Abou-Khaled, K., Williams, J. M., Yazeji, M., Haselgrove, J. & Faro, S. (2003). Diffusion Tensor Imaging of the Hippocampal formation in temporal lobe epilepsy. American Journal of Neuroradiology, 24, 1857-1862. On 12/8/12 11:00 PM, Teaching in the Psychological Sciences (TIPS) digest wrote: > Subject: MRI Diagnosis > From: don allen<dap...@shaw.ca> > Date: Sat, 8 Dec 2012 10:15:55 -0700 (MST) > X-Message-Number: 3 > > I just read the following study in PLOS one titled: Anatomical Brain Images > Alone Can Accurately Diagnose Chronic Neuropsychiatric Illnesses. > > It can be found here: > > http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0050698 > > The claims of the study seem impressive: > > "In MRI datasets from persons with Attention-Deficit/Hyperactivity Disorder, > Schizophrenia, Tourette Syndrome, Bipolar Disorder, or persons at high or low > familial risk for Major Depressive Disorder, our method discriminated with > high specificity and nearly perfect sensitivity the brains of persons who had > one specific neuropsychiatric disorder from the brains of healthy > participants and the brains of persons who had a different neuropsychiatric > disorder." > > The research design seemed to be adequate (at least to me) but I don't have > enough detailed information about MRI to know whether this is a really > important breakthrough or just another soon-to-be-forgotten study. The fact > that it was published in PLOS one rather that Science or Nature makes me > suspect the latter. Would anyone with more expertise in interpreting MRI data > like to provide some comments on the study? > > Thanks, > > -Don. --- You are currently subscribed to tips as: dap...@shaw.ca. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13157.966b795bc7f3ccb35e3da08aebe98f18&n=T&l=tips&o=22259 or send a blank email to leave-22259-13157.966b795bc7f3ccb35e3da08aebe98...@fsulist.frostburg.edu --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=22269 or send a blank email to leave-22269-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
