The first psychiatric patient I evaluated—42 years ago—presented with delusions and mood swings and received a diagnosis of schizoaffective disorder from our attending physician. We medical clerks were skeptical. Schizoaffective disorder seemed a violation of our education in the distinctness of illnesses, with well-defined syndromes linked to discrete disease mechanisms and specific treatments.
The patient recovered. I went on to study psychiatry and its diagnostic criteria further. Strictly defined categories became more standard in the field. These were tempered with arguments for continua (thus, schizoaffective disorder lay midway between schizophrenia and bipolar disorder), and some distinctions were conceived along axes, with the DSM picking 2. Domains, abnormalities with more unitary features than diagnoses, were also suggested. Meanwhile, the most frequently used approach clinically assigned multiple diagnoses to individual patients, often as “rule outs” and not as single categories.
Cohen BM. Embracing Complexity in Psychiatric Diagnosis, Treatment, and Research. JAMA Psychiatry. Published online November 09, 2016. doi:10.1001/jamapsychiatry.2016.2466