It is important to have a diagnosis if you need your health insurance to pay for your treatment and your health insurance won't do that without a diagnosis.

That is about it in my honest opinion.

Current DSM nosology (and ICD for that matter) lists behavioural (including verbal behavioural) symptoms. If you meet however many out of however many symptoms then congradulations you fit into that diagnostic category. Diagnoses don't *explain* why you have the symptoms you have. Diagnoses (in my honest opinion) really aren't good for a whole heap except as a pre-requisite to get certain kinds of treatment.

The major drive behind the DSM listing more and more and more diagnoses with each edition isn't to do with good science or descriptive adequacy or with providing a better tool for research. The major drive behind the DSM listing more and more and more diagnoses with each edition has to do with politics. In particular, politics around what health insurers will and will not provide for.

Sometimes people come to internalise their diagnostic category. They read about 'typical people with diagnosis x' and they come to... Well they come to behave in such a way as a matter of self fulfilling prophecy. The looping effect of categorisation...

That is why the worst prognosis for schizophrenia is living in an industrialised western country. People in other cultures do much better with recovery. In western society, however, we like to tell people they are 'chronic', institutionalise them, stigmatise them, and drug them off their faces.

IMHO diagnosis doesn't matter unless you have to deal with your health insurance company.

Regarding medications... Medications work on symptoms not on diagnostic categories. That means that diagnosis is not relevant for medication, it is the particular symptoms you are experiencing that are relevant.

Using a diagnostic category to *explain* symptoms is like this:

Q Why does the drug put people to sleep?
A Because it has sleep inducing power.
(Problem: We only say it has sleep inducing power BECAUSE it puts people to sleep thus we have a CIRCULAR explanation)

Q Why do I have these symptoms?
A Because you have this diagnosis.
(Problem: We only say you have that diagnosis BECAUSE you have those symptoms thus we have a CIRCULAR explanation)

Of course some people find it helpful to know there are other people like them and they are not alone. In my honest opinion one can meet other people with similar symptoms across a whole range of diagnostic categories and all diagnostic categories really do is confuse the issue... Oh and make a lot of money for the American Psychiatric Association, of course...