Brain scans are not standard first-line tools for psychiatric disorders because neuroimaging biomarkers face significant challenges regarding diagnostic limitations, poor generalizability at the individual level, and a lack of clear clinical utility.
The retrieved literature consistently emphasizes that while neuroimaging holds theoretical promise for psychiatry, current methodological limitations—such as poor generalizability, sampling inequalities, biological heterogeneity, and low individual-level predictive accuracy—prevent brain scans from serving as standard first-line diagnostic tools. All relevant papers addressing psychiatric neuroimaging support the existence of these diagnostic limitations.