Drugs

Baroness Greenfield Excerpts

Thursday 17th October 2013 Lords Chamber

[Baroness Greenfield (CB)]

My Lords, I congratulate the noble Baroness, Lady Meacher, on bringing attention to these important reports. I declare an interest as an ambassador of the Angelus Foundation, which aims:

“To help society understand the dangers of ‘legal highs’”.

As a neuropharmacologist researching the cellular mechanisms underlying various neurological and mental disorders, I have a particular interest in the impact of recreational drugs on the brain. After so many eloquent and informed speeches, I would like to make just two points.

The first is to question the actual meaning of the phrase “relatively less harmful”. Much is often made of the fact that, in a 2007 paper, cannabis came in with a final net score lower overall than that for tobacco or alcohol, suggesting that it might be safer, but then again, in the same paper, cannabis scored higher than LSD, which is widely regarded as a model for psychoses such as schizophrenia. Is having hallucinations really more welcome than, say, the relaxing effects of moderate amounts of alcohol? Similarly, on the same scale, cannabis also had a higher score than ecstasy, a drug for which in the past five to six years more than 60 papers have documented adverse short and long-term effects on the brain. Therefore, on that comparison, cannabis should be more harmful. Moreover, smoking cigarette after cigarette in one sitting is unlikely to achieve an “overdose” akin to a single session of marijuana that can send smokers to A&E with acute panic attacks.

These drugs all have detrimental effects, but they are qualitatively different. Surely any direct comparison is like benchmarking apples against pears. Further factors might come into play, such as the differential effects of certain drugs on the still developing adolescent brain. In teenagers a certain region, the prefrontal cortex, is still not fully operational, accounting perhaps for the tendency of young people to take more risks and seek sensation. This, in turn, may be reflected in the differential statistics, where the risk of cannabis addiction has been estimated for adults to be about one in 10, but almost doubles for teenagers to one in six. A recent report in the Lancet has documented cannabis as having a dependence syndrome in the young, including,

“increased risk of motor vehicle crashes, impaired respiratory function, cardiovascular disease and adverse effects on adolescent mental health”.

Subsequently, a paper published in Proceedings of the National Academy of Sciences has shown that persistent cannabis use was associated with neuropsychological impairment among adolescent-onset users, for whom cessation did not fully restore neuropsychological functioning. Confounding factors such as socioeconomic status or personality differences were subsequently eliminated: the link appears direct between cannabis use and an irreversibly lowered IQ. No similar claims have been made for nicotine. Even if such qualitatively different drugs could be compared on a quantitatively single scale, the crucial question is then: just how harmful is a “less harmful” drug? The phrase lacks any precise definition, and cannot therefore really be used as a valid justification or a starting premise.

My second point relates to the paradoxical signals sent out that, although the laws may be relaxed on a drug, it is still to be avoided. Already the possibility of cannabis legalisation is all too readily glamorised as a cool and trendy campaign to support, with little negative publicity offsetting that image, in contrast, for example, with tobacco. It would be helpful to know how the preventive programmes mentioned in the reports—we have heard too little about those this afternoon—will be funded and rolled out. The reports paint a rather gloomy picture of the preventive programmes, yet one initiative they did not explore, which has proved successful, is a community-wide approach, such as the one in the US, where community anti-drug coalitions have shown positive impacts when a community-wide response is taken up.

Another possibility has been prompted by my own experience of speaking in schools and penal institutions on drugs and the brain. Adults and teenagers alike get fascinated by basic neuroscience that can give insights into drug action: the “plasticity” of the brain whereby dynamic, endless reorganising of individual neuronal connectivity is driven by individual experience through chemical messengers signalling between different brain cells. It is this chemical transmission, this plasticity, that is modified in various ways by different recreational drugs. If this personalisation of the brain could be the individual mind, then “blowing your mind” might be an unintentionally accurate description. I have found from experience that this carries weight with young audiences.

Other noble Lords have spoken on the legislative and political merits of the recommendations of these reports. I would urge that such considerations be placed in the wider context of a thought-through programme of prevention that should first be in place and proven to be effective.