Pharmacological Approaches to Addiction

Drugs and Brain

There are few health problems that generate as much debate and as many different positions as drug addiction, both with the general public and with sector professionals. For the general public, drug addiction is often synonymous with bad habits, decadence, and delinquency.

 

Drug addicts are supposed to be weak beings who prefer to give themselves over to artificial hells instead of facing reality like the rest of the world does. For others, drug addiction is an illness like any other: drug addicts need medical care, including daily treatment, just as diabetics need their insulin. While this latter vision is progressive and reflects greater compassion, with respect to those that point to the addict as a marginalized figure, it continues to be only a comfortable and overly optimistic way of approaching the problem. These competing views notwithstanding, the fact is that if drug addicts are sick, we need to identify the responsible genes, find the most efficient treatment, discover the vaccinations that need to be adapted and finally free ourselves from this calamity, just as we eradicated chicken pox in its day.

Among professionals, there is a broadly generalized consensus about the bio-psychosocial nature of drug dependency, caused as a result of a series of encounters, spaced out over time, between one person and a psychoactive substance in a given context. The main characteristic of this approach is to consider the person as a whole and a globality in the different planes of their life: e.g. the biological, the psychological, the social and even the cultural.

However, there are substantial differences among professionals with respect to the relative importance of biological, psychological and social determinants. The majority of professionals devoted to intervention in the area of drug dependency prioritize the social, cultural and environmental determinants at the beginning and the continuation of the addictive behaviors, while doctors, researchers and others in the scientific community tend to make it clear that they feel that addiction is a cerebral illness that we can cure one day through different pharmacological approaches.

A little about neurobiology

Eating, drinking, reproducing, etc. are essential activities for the survival of the individual and the species. Over thousands of years of evolution, natural selection has associated sensations of satisfaction and pleasure with these behaviors. A true reward circuit thus has been developed in our brain, favoring these behaviors related to our basic needs.

This circuit became progressively more complex, leading us to repeat the agreeable experiences that we learn throughout our lives – listening to music, reading a good book, establishing enriching relationships, etc. The reward circuit is therefore found at the heart of our mental activity and is oriented towards the whole of our actions. However, in order to be able to feel satisfaction, a messenger must activate the reward circuit, passing through each neuron. This chemical messenger is dopamine, an infinitesimal chemical molecule, released by the neuron, which will act on other neurons, connecting to precise sites, the receptors, like a key that is inserted into a lock.

Cocaine, ecstasy, tobacco, alcohol or, in other words, all products liable to lead to dependency, have one property in common: they increase the quantity of dopamine available in the reward circuit. Effectively, drugs have molecular structures that resemble the natural substances that are produced by our bodies. To pick up the same analogy again, they act as false keys that are inserted into the lock, producing its effects on the reward circuit.

Upon altering the functioning of this natural circuit, drugs create an imbalance in the brain’s operation, slowing down the production of natural substances. To re-establish a certain balance, the addict turns to taking drugs again. – more of them and more often. And the dependency is installed. With an abrupt stop in consumption, the imbalance is at its height: the brain has not “relearned” to produce natural substances that are linked to pleasure, and from that point there occurs the appearance of intense psychological suffering, including extremely unpleasant physical symptoms in the cases of heroin and alcohol.

Drug addicts consume drugs in the beginning to seek pleasure and later to prevent suffering (abstinence symptoms). This is what addiction is. However, the use of drugs to prevent withdrawal symptoms and therefore, suffering, is not the sole reason for addiction.

Many people have relapses a long time after the symptoms connected to the withdrawal have disappeared, for example, after being exposed to environmental stimulations (presence in places of consumption, stress) or after having consumed a small quantity of the drug. Present-day knowledge lets us suppose that the fact of drinking or taking drugs intensively and for a long time, trains persistent neurophysiological modifications, which explains cravings, the irresistible need to consume alcohol or other drugs, even years after have managed to stop using them.

Current situation and clues for solution

Today it is a certainty that drugs artificially activate the reward circuit in the same way that a good meal among friends or a concert featuring our favorite music does. From there emerges the idea of using molecules liable to trick the dopamine receptor, thus relieving the drug addict from his need to consume drugs.

But it seems like there are still distances to travel before this point is reached, because designing new molecules is an extraordinarily complex process and even more so for drugs whose use is aimed at the brain. Effectively, the central nervous system is separated from the blood by a barrier, called the hematoencephalic, which prevents the passage of numerous substances. In this way, interesting molecules can be stopped in their attempt to reach our brains.

Despite this obstacle, we do already have different medicines available. For heroin and other opiates, methadone and buprenorphine act as agonists. That is, molecules whose purpose is to occupy the place of heroin in the suitable receptors and produce more or less the same effects. Naltrexone, in turn, acts as an antagonist or, in other words, it occupies the heroin receptors, therefore preventing that the heroin can establish itself there, but without producing the least psychotropic effects. It remains only to be stated that this molecule is not attractive to drug addicts.

For alcohol, there is another type of treatment, disulfiram, which discourages chronic drinkers by producing whiffs of heat, vertigo, vomiting and tachycardia. Not in the least agreeable either.

We are left with vaccinations. In this field, the most promising molecules relate to nicotine and cocaine. This area is a true brainteaser still, since in order to be able to obtain an immune response, the molecules have to be sufficiently large to be recognized by the immune system, which hasn’t yet happened. The English laboratory Xenova seems to be at the point of rising to the challenge, by associating a protein that is easily identified with this molecule by the immune system, which will produce antibodies that prevent the cocaine molecules from reaching their neuron receptors.

The limits of pharmacology

It seems unrealistic to define the problem in exclusively neurobiological terms, as the risk is run of minimizing the cultural and social dimensions of drug addiction and the contribution of human sciences. On the other hand, a significant number of drug consumers do not see themselves as potential patients that could be cured by a simple jab, and some sector professionals are skeptics as well. Beyond the effectiveness of a treatment on the animal model, it must also be taken especially into account that the treatment must be acceptable for drug consumers, as those involved in their health care services must be as well. We cannot forget to mention that the social exclusion mechanism of drug dependent individuals in itself represents a large obstacle in reaching them, understanding them, winning their trust and offering them suitable pharmacological treatment.

There are also ethical issues involved. If one day we manage to find medicines or even vaccinations that are really efficient, how will society react to those people who refuse to take them? Will their choice be considered legitimate or will it, conversely, just heap more exclusion onto their exclusion?

To conclude, there are few probabilities that a medicine is going to be effective on the social, cultural and environmental factors that also characterize addictions. There are few probabilities that a medicine, however miraculous it may be, can replace the years of the slow demolishing of family and social ties, the many broken bridges and, This Life, that drug addicts watch go by, from the other shore …

Psychosocial accompaniment measures will almost definitely continue to be essential. So it is not about treating the dependency exclusively with one option or the other, but rather about adopting an overall therapeutic approach within a climate of tolerance, respect and recognition of the person and his place in our society.

Pierre Bremond CDC, communication Dianova