herald

Tuesday 24 October 2017

Dear Doctor: Depression

Can my doctor prescribe ketamine to treat my depression as I seem to be resistant to other medications?

I READ recently about a drug, ketamine, that can be used to treat depression. Can I get this from my doctor? I have been on a number of medications for depression but none work.

A recent study looked at the anaesthetic drug ketamine in the treatment of depression in patients with treatment resistant bipolar disorder.

This drug has traditionally been used as an anaesthetic for animals and in some cases humans, but has also established itself as a ‘recreational’ narcotic “Special K”.

In this study, scientists discovered that rats stopped displaying symptoms of depressive behaviour within hours of receiving a dose of ketamine. Another study a number of years ago found that depressed people's symptoms improved when given a dose of ketamine.

The concern with ketamine is that it has to be injected and can cause hallucinations. It is a very addictive drug, which is normally used on horses only. It's not available on prescription from your GP.

How does ketamine work?

Researchers are hoping to learn from how ketamine progresses through the nervous system, which is different from traditional drugs, for the treatment of depression.

It appears to work by forming new synaptic connections between neurons, a process called synaptogenesis.

Ketamine acts on the brain's glutamatergic system, which plays an important role in information processing and memory formation. Dysfunction in this brain system may contribute to bipolar disorder or depression. Targeting the brain's glutamatergic system may lead to better treatments in bipolar or depressive disorder, but more research is needed.

Why do some people respond quickly to treatment and others don’t? Why didn’t the previous medication I’ve taken work?

Finding the right medication for you may take some trial and error. This requires patience on your part, so don't give up. Most antidepressants need several weeks or even months to take effect and must be taken daily. Talk to your doctor about your concerns. If antidepressants don't seem to be working, your doctor may recommend a blood test to check for specific genes that affect your body's use of antidepressants. The cytochrome P450 (CYP450) genotyping test is one example. Genetic testing of this kind can help predict how well your body can or can't process a medication. However, these genetic tests aren't widely available.

Medication is usually not enough in the treatment of depression. Most people benefit from a combination of medication and counselling, preferably cognitive behavioural therapy.

This advice is to help you make informed decisions about your health. Not all the advice may be suitable if you are pregnant or breastfeeding. Always consult your doctor. Our health advisers won’t enter into personal correspondence.

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