Dr Andrew Macaulay:
During my professional lifetime, psychiatry has fundamentally remained a clinically descriptive specialty and in truth, special investigations have rarely helped in diagnosis and management. Somewhat ritually, we arrange haematology, urea & electrolytes, liver function tests and thyroid function; occasionally there are some incidental abnormalities.
Apart from Lithium level and possibly thyroid function, special pathological investigations have little practical use in the management of psychiatric disorders. Treatment resistant depression is one of the most serious clinical situations referred to me and, I expect most other psychiatrists, because there is everything to play for. Get it right, recovery is the prize; if not, catastrophe. Medication almost always has a critically important part to play with this group of patients. Invariably, they have tried two or more without success; until recently, I have had to impress on the patient and their families the critical importance of working through the medication in a methodical fashion, hoping that eventually an effective anti-depressant will be found for them.
Genetic testing does not improve the efficacy of medication of course; what it does is ensure that you don’t prescribe something that is ineffective. It also explains why previous prescriptions and treatment plans have been ineffective and under these circumstances, the patient finds it reassuring, because they now have an explanation for why they are no better. Testing at the moment is relatively expensive, but whenever I have suggested it to the family, they have been happy to pay for it. Remarkably, the results have always informed prescribing which puts me in the fortunate position of only suggesting the medication to which they are likely to respond; and for the most part, they do.
I am confident that soon every patient, who is described as treatment resistant, will have genetic testing. It is a simple and effective investigation and in my experience, with every single patient, it has facilitated effective management, enhanced the instillation of hope and saved lives.