The next edition of psychiatry's diagnostic manual is expected to add biological factors, such as genetics and signs of inflammation, to a system that has long relied on interviews and symptom checklists, a psychiatrist who served on a planning committee told Live Science. For decades, clinicians have used the Diagnostic and Statistical Manual of Mental Disorders, or DSM, to diagnose conditions including major depression, anorexia, and post-traumatic stress disorder. Dr. Anand Kumar, head of the Department of Psychiatry at the University of Illinois Chicago, served for two years on the DSM Strategy Committee. In an interview with Live Science's Kenna Hughes-Castleberry, he said one of the most important potential changes in the forthcoming DSM-6 is the introduction of biological factors into the diagnostic framework.
"Up to this point, the distinctions between the different major groups ... have been based exclusively on clinical grounds: You meet certain criteria, and you fall into this category," Kumar said. Attempts to add biology have been discussed before, he said, but it was difficult to get a consensus on what belongs in the manual. "That's still going to be tricky, but at least there's a broad acknowledgement that the time is ready to start introducing biology into the DSM." Possible additions include data from genome-wide association studies of hundreds or thousands of genes that each slightly raise the risk of a disorder, as well as signs of inflammation or immune-system dysfunction that may show up in blood tests or brain scans. Kumar no longer serves on the committee, but he was involved in those discussions.
Some of that biology already exists in pockets of medicine. Kumar told Live Science that Alzheimer's disease now has blood tests that can detect abnormal levels of tau and beta-amyloid, the proteins that form the plaques and tangles associated with the disease. Those tests have received U.S. Food and Drug Administration approval. The picture is different for common psychiatric diagnoses. About 30% of people with major depression show some evidence of immune-system involvement, he said, but there is no simple blood test that can diagnose depression or tell a clinician which treatment will work. The planned DSM-6 changes, in his account, are incremental: they would let biological findings sit alongside symptom criteria, not replace them.
Kumar, whose research focuses on late-life depression and Alzheimer's disease, said the update is "very likely" to produce meaningful changes "in a positive kind of way." "It's not going to make everyone happy. There are going to be gaps, but the idea is to incrementally improve this and make it more modern as we go along." The verified claim is that planners are preparing to add biological markers to the next DSM, and that some of those markers, especially in dementia, already have approved tests. It is not a claim that psychiatry as a whole now has a single blood test for mental illness, or that the new manual has already been published.