Category Archives: Mental health

New insights into how antidepressants work.

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fMRI scan.

It is well established that antidepressants take at least 2 weeks to shift a depressed mood. A new study from researchers at Oxford, reveals that the drug is working behind the scenes, much earlier than this.

People with depression are known to show an exaggerated response to pictures of human faces that are expressing fear. The response can be observed using functional MRI brain scanning. The part of the brain which lights up is their own 'fear processor', the amygdala. The usual interpretation is that the depressed patient's fear system is unduly sensitive to anything from the outside world which signifies fear. And human faces elicit the most robust response.

Previous work had shown that standard SSRI antidepressants can dampen down the hyperactive amygdala, and return it's function to normal. What was unknown was whether the effect on the amygdala or the effect on mood came first.

The Oxford researchers have now shown that SSRI antidepressants dampen down the amygdala at least 1 week before the patient experiences a shift in their mood. They compared 3 groups of people: depressed patients who had been randomised to receive escitalopram (10mg); depressed patients who had been randomised to placebo; and a group of healthy controls. A week after being randomised to active drug or placebo, the depressed patients were given an fMRI scan.

The main finding was that the patients who had been taking escitalopram for a week had normal amygdala responses to pictures of fearful human faces. In contrast, the patients on placebo showed the characteristic hyperactive response in the amygdala on the right hand-side of their brains (see scan above). Notably, 1 week was too early for any antidepressant effect – Treated and untreated patients were equally depressed at this stage.

This is an important finding, which shows that SSRI antidepressants affect how the brain processes emotional information before the patient feels an improvement in their mood.

Further studies are planned. One key goal will be to assess if the degree of amygdala dampening at 1 week can distinguish between patients who ultimately get better from those who will remain depressed. The technology might even be used in selecting the 'best' type of antidepressant drug for a particular patient, rather than having to adopt a 'wait and see' approach.

The full paper can be read here

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3488813/

 

Is cannabis addictive?

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For many years it was assumed that cannabis was not an addictive substance. This view was based on the apparent lack of a cannabis withdrawal syndrome. The absence of a withdrawal syndrome was said to distinguish cannabis from ‘hard drugs’, such as opiates and cocaine, and even from the two most widely used ‘soft drugs’, nicotine and alcohol.

Recently a number of studies have established that a cannabis withdrawal syndrome does indeed exist. In the latest of these, 49 users agreed to try a 2-week cannabis free period.

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0044864

As in previous work, participants reported a number of symptoms during abstinence. Symptoms included difficulty sleeping, anxiety, mood swings, physical tension, stomach pain and craving. Symptoms peaked at around 4 days and then gradually decreased over the next 10 days. 

Notably, those who experienced the most severe withdrawal symptoms were more likely to relapse and begin taking cannabis again. They also experienced more functional impairment during abstinence. 

This study highlights the difficulties people can experience when they attempt to give up cannabis. It also demonstrates that the withdrawal reaction is an important factor in determining whether an attempt at abstinence is likely to be successful. 

 

 

N-acetylcysteine: Effective in bipolar depression?

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N-acetylcysteine (NAC) is a derivative of the naturally occurring amino-acid cysteine. Many people use it as a nutritional supplement, but NAC also has clear pharmacological properties. By far the most important role of NAC is as an ‘antidote’ in cases of paracetamol overdose. In this role, it can be life-saving.

However, the properties of NAC may extend beyond the emergency room. Recent research from Australia suggests it might be effective in the depressive phase of bipolar disorder. http://www.scielo.br/pdf/rbp/v33n4/v33n4a11.pdf

Larger studies are needed, but if the initial promise holds true, this would represent an important advance. In bipolar disorder, the depressive phase can be extremely difficult to shift, although conventional pharmacology has also made some significant inroads in the past few years. http://journals.psychiatryonline.org/data/Journals/AJP/4013/1351.pdf

 

Major Depression: What is currently known?

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“About one in five people will suffer from major depression at some point in their lives. Aside from the psychological burden, people suffering from depression are known to be at higher risk of heart disease”.

But what are the causes of depression? What happens in the brain when someone is depressed? And which treatments work best?

Writing in the Lancet, Phillips and colleagues from the University of Pittsburgh give an authoritative account of the current state of the art. They appraise the evidence for antidepressant drugs and psychological therapies, and highlight promising new treatment strategies.

Kupfer DJ, Frank E & Phillips ML (2012) Major depressive disorder: new clinical, neurobiological and treatment perspectives. Lancet 379:1045-55.

The full article is available at:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3397431/

Cannabis and schizophrenia

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Recently Dr Paul Morrison was quoted in an article by Patrick Cockburn in ‘The Independent’ on Cannabis and its relationship to mental health problems.

“Cannabis consumption has been falling in Britain as well as the rest of northern Europe since 2004, but the age when teenagers start taking the drug is also going down. There has been a nearly 20-fold increase in first-time use by under-18s, with 40 per cent of under 15-year-olds in the UK having used the drug. This is a dangerous trend. Dr Morrison says “adolescence seems to be the critical variable when the neural-circuits are being sculpted and the personality is emerging”.

To read the article in full please use this link:
http://www.independent.co.uk/life-style/health-and-families/health-news/is-this-the-tobacco-moment-for-cannabis-8349054.html