Select Committee on Home Affairs Appendices to the Minutes of Evidence


Memorandum submitted by Baroness Greenfield

  I shall limit my comments to those within my area of expertise, neuropharmacology. Although I am concerned by the effects of drugs on the body as a whole, my specific concern relates to the actions of drugs within the brain. Moreover, my views are based not so much on the question of ill-health and death, but rather on the changes in outlook that can occur with drugs. I believe that a society composed of citizens who, even if not physically at peril are, nonetheless over or under-stimulated because of drugs, would not constitute a desirable society.

  In order to explore how drugs in general might change the mind, it is important to set to one side the differences in their chemistry and, indeed, the chemical systems they target. With the probable exception of alcohol, all drugs work on one or more types of "transmitter" systems in the brain: they do so by modifying the availability, disposal or molecular target (receptor) of the transmitters in question. Alcohol works less specifically on the general propagation of electrical impulses within neurons, although there is some evidence that it may work in close conjunction with some transmitter systems rather than with others.

  Although the action of the transmitters themselves is short-lived, repeated neurotransmission changes the connections on a more permanent basis. Repeated use of a synapse will "strengthen" it. We now know that this change in the efficiency of the synapse is caused by changes within the brain cell, via genes that can change the proteins and even the shape of the target neuron. Another long-term change is that if the receptors ("targets" for transmitters) are over-stimulated, they become less sensitive, rather like a handshake where the hand becomes increasingly numb if continuous pressure is applied. We know that this "desensitisation" of receptors, is one of the factors in addiction. Hence, "modification" of transmitter systems may have serious and long-lasting effects on the brain, and hence on the way we see the world.

  Although we are born with more or less all the brain cells we will ever have, it is the growth of the connections between these brain cells that accounts for the growth of the brain after birth. These connections will mirror individual experiences, even if one is a "clone", ie an identical twin! I have suggested that it is the plasticity of the brain, its personalisation through experience, that could be regarded as the "mind" (Private Life of the Brain, Penguin 2000). Moreover, not only does the mind evolve as these connections are gradually forged as a result of our experiences, but this "plasticity" continues throughout life. Hence we are seeing the world endlessly updated in the light of our previous experiences.

  If drugs work on the connections that in turn act as a physical basis for the way we evaluate people, objects and events, then it is easy to see how these same chemicals could literally change or even "blow" the mind. Clearly, the severity of the drugs are classified legally according to how dangerous they are in terms of health, and the risk of death. But my own view is that all drugs should be regarded as dangerous, in that they have the power to modify the mind long-term. Indeed, it is hard to see how drugs could not have these actions, given their effects on mood and, allegedly in some cases, on pain relief. Hence the arguments articulated for cannabis in the enclosed document, written for The Project Syndicate in Sweden (An Association of Newspapers Around the World) may also be extended in principle to drugs such as Ecstasy, cocaine, heroin and amphetamine.

  The single important point I wish to emphasise is that it is not as if the individual is an inviolate entity, separate from his or her experiences. Anyone who takes drugs will run the risk of changing their personality and their view of the world.

  Such arguments would indeed extend to prescribed as well as proscribed drugs. It is simply that for medicinal reasons the cost benefit analysis is more justified.

  In my view, there are three general areas that have received insufficient attention in considering how to deal with drugs and society:

    —  improving education in how drugs work in the brain. Although the brain is considered a technical subject, I have myself spoken to 11 and 12 year olds, about the broad way in which drugs work on transmitters, and have had very favourable and grateful feedback from children and parents. Indeed, I have also spoken at Brixton prison, at the invitation of the inmates, who were concerned over drug-related crime. They had no idea of how drugs worked on the brain and appeared, at least, to be fascinated;

    —  more neuroscientific research into areas of contentious debate concerning relative doses of alcohol, cannabis and other drugs, on brain cell viability; and

    —  more initiatives exploring the real motives as to why people take drugs, eg peer-pressure, a desire to seek oblivion, or the need for some new type of experience.

  Such projects would involve a vast range of different constituencies from schools, the media, and social services. Psychologists and neuroscientists could also make a valuable contribution in exploring what is happening in the brain when someone takes drugs, and how such experiences are analogous to non-drug taking, but pleasurable scenarios (see Private Life of the Brain Penguin 2000).

  In summary, a softening of the laws on drugs, including decriminalisation, would be sending out signals to society, especially to young people, that drugs are not really harmful and, perhaps even more importantly, that this is an answer to the problems of life.

January 2002

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