This is very odd indeed!
"... Researchers ... analyzed thousands of brain scans collected in earlier studies to better understand the reasons for these observed inconsistencies. Their findings ... suggest that many widely used experimental designs and tools might fail to reliably capture the subtle differences in brain structure linked with distinct psychiatric disorders. ...
"... To quantify the severity of this inconsistency, the study involved a world-first analysis of more than 6,000 brain scans, evaluating the consistency of grey matter volume and cortical thickness. Researchers pooled existing MRI data from 25 studies across 59 sites globally, covering five major psychiatric disorders: schizophrenia, schizoaffective disorder, autism spectrum disorder, major depressive disorder, and bipolar disorder. ..."
but decades of research using brain-scanning technologies such as magnetic resonance imaging (MRI) have failed to reach a consensus about which brain changes are most characteristic of different psychiatric disorders. ...
the findings suggest categories like "depression" may not describe people with the same underlying brain condition; instead, they may represent an umbrella term that groups together people with symptoms caused by distinct sets of brain changes. ..."
From the abstract:
"Decades of structural magnetic resonance imaging (MRI) studies have documented alterations of gray matter morphometry in psychiatric disorders, but the field has failed to identify any consensus disease phenotypes.
Here we examine whether current approaches will ever converge on such phenotypes by evaluating the consistency of brain-wide maps of gray matter volume and cortical thickness differences obtained for each of 59 study sites of five psychiatric disorders (schizophrenia, schizoaffective disorder, autism spectrum disorder, major depressive disorder and bipolar disorder), totaling 2,437 patients and 2,065 controls.
We find that cross-site consistency is low (median r ≤ 0.16); markedly reduced compared to Alzheimer’s disease (r = 0.54); unexplained by demographic, clinical or scanner differences; and robust to analytic choices.
Using bootstrapping, we observe that consistency may improve for sample sizes ≥200 per group for schizophrenia but that other disorders may require much larger samples.
Our findings indicate that current widespread practices in structural MRI are unlikely to identify robust morphometric phenotypes for psychiatric disorders."
Monash study reveals decades of psychiatric brain imaging research has failed to replicate (original news release)
Fig. 1: Analysis pipeline.
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