20 June 2016 07:00:03

Depression - first steps to tailored treatment?

Antidepressants, like all tablets, can cause side effects. So recent news of a blood test which could identify which patients with depression are most likely to benefit from taking them caught my attention...


As a GP, never a day goes by without me seeing at least a couple of patients with depression. About two in three people will have symptoms of depression at some point that are bad enough to have an impact on their lives. But depression is a spectrum, and about one in five women and one in 10 men will have 'major depression' at some point. At any given time, between one in 10 and one in 20 have major depression.

There are lots of scales used to measure depression. It's a very inexact science, because if relies on people thinking about how they've felt in the last few weeks. In the UK, we mostly use a tool called the 'PHQ9' scoring system. It has a lot in common with the DSM-IV criteria (from the American Psychiatric Association) which are used by the National Institute for Health and Care Excellence (NICE) to measure depression.

For a DSM-IV diagnosis of depression, you must have at least five symptoms of depression lasting for at least two weeks, which represent a change from how you usually feel. One of these has to be either low (depressed) mood or loss of interest or pleasure in things you would usually enjoy. Others include:

- Change in appetite or weight when you're not dieting

- Change in sleep patterns (sleeping to excess, problems getting to sleep, waking early or waking up frequently)

- Persistent tiredness or lack of energy

- Problems concentrating

- Feeling worthless or guilty about things that aren't your fault

- Being agitated or slowed down enough that others have noticed

- Thoughts of harming yourself, of feeling you'd be better off dead.

Depending on how frequent these symptoms are, how many you have and how much they're affecting your life, depression can be classified as 'subthreshold', mild, moderate or severe.

Doctors have often been accused in the past of being too quick to put patients on to antidepressants. One of the major issues has been lack of availability of talking therapy, which can be as or more effective than medication. The situation is improving with more investment in counselling services - you can now refer yourself for counselling on the NHS via the national service called IAPT (Improving Access to Psychological Therapies). Even if antidepressants are recommended, counselling can help in conjunction with it. I certainly never suggest starting antidepressants without exploring the non-drug options first.

Antidepressants can - quite literally - be life-savers. But they rarely help in mild or mild-to-moderate depression, and even in more severe cases they don't always work. I sometimes have to prescribe two or even three types of tablet for a patient before we find one that works for them. And antidepressants, like all tablets, can cause side effects. So news this week of a blood test which could identify which patients are most likely to benefit from antidepressants had me poring over every word.

The study involved is fairly small (just 140 patients) but the results are promising. Researchers looked at levels of two blood indicators of inflammation - MIF and interleukin-1 beta. Higher levels of these two markers meant a much lower chance of antidepressants working. The researchers suggest that inflammation may be part of the body's reaction to stress, but that this may interfere with the mechanism by which both SSRI and tricyclic antidepressants work.

This study doesn't provide any clues to which antidepressant might work for any given patient. It also doesn't provide answers as to what the alternatives should be for patients found to have high inflammatory markers. But it does open up the prospect of studies into whether giving anti-inflammatory tablets alongside antidepressants might overcome the interference. It also gives doctors a possible way of predicting if a patient is likely to benefit from antidepressants - reducing the chance of patients suffering side effects with no benefit. It's early days, and I won't be offering these tests in my consulting room yet - but it's progress.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.