The Official Psychiatry Manual Is Ridiculously Inaccurate
In the United States, The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the recognized authority on diagnosing mental illness. It's so influential, in fact, that most folks in the field just call it "the Bible."
Unfortunately, much like that other Bible, some parts are so outdated that they may be doing more harm than good. The existing research strongly suggests that mental illnesses lay on a spectrum, like so:
We assume "fear of bright colors" has its own chart.
However, textbooks love nothing more than clean spaces and nice, orderly tables, so the DSM still stubbornly splits mental illnesses into neatly defined ailments. Science offers little support for this: When tasked with finding genetic or neuroscientific evidence to back the DSM cataloguing, biology slowly backs away and spends the rest of the night sobbing in a bottle. But because hard science has also yet to produce any conclusive information on the nature of mental disorders, and since the DSM has been the go-to guide of the industry since the 1950s, that's what psychiatry opts to roll with.
Sure, maybe they'll come around and revise the DSM for the better in its next iteration. It's just that, so far, the bastard has been revised every 15 years or so, and its latest version -- the one that still includes all that stuff described above -- just came out in 2013. Right now, the manual's arbitrary criteria are a giant problem for medical research. Treating actual patients with it is like attempting to fine-tune a race car using an old, filthy shop manual ... for a combine harvester.
"The language is kind of vague, but it looks like the first treatment step is to check your spark plugs."