On 2014 Sep 16, Serge Ahmed commented:

In this new Shattuck Lecture, Eric Kandel and Denise Kandel (K2) announce that they will let science speaks for itself about the role of “nicotine as a gateway drug” to other drug addictions and will not distort “what science does and does not tell us” about this controversial matter, as many others would generally do.

However, this paper is more about cross-sensitization between nicotine and other drugs in mice than about “nicotine as a gateway drug” to other drug addictions in human populations. Basically, K2 present evidence showing that forced pre-exposure to nicotine can enhance the proportion of individual mice that become sensitive to the stimulant and rewarding effects of a low dose of cocaine. In fact, after nicotine pre-exposure, a large majority of mice become sensitized to cocaine (i.e., up to 78-98% of mice). This proportion contrasts with the small minority of cigarette smokers who go on to develop cocaine addiction in human populations (i.e., 20%). This large discrepancy complicates the extrapolation between mice and humans but is ignored by K2. Would it imply that nicotine-exposed mice are more vulnerable to cocaine addiction than cigarette smokers? Or, more likely, would it indicate that nicotine-induced sensitization to cocaine per se should not be confused with cocaine addiction?

Research on cross-sensitization between different drugs, including nicotine and cocaine, in rats and mice were very popular among addiction researchers in the 80s and 90s. However, because drug sensitization is clearly not drug addiction, these studies have since been replaced by other, more valid animal models of drug addiction. This research is entirely ignored by K2. Thus, it remains to be demonstrated whether and to what extent initial nicotine self-administration in mice or rats can increase the proportion of individuals that develop more relevant behavioral features of cocaine addiction. Thus, we are back to the initial “scientific question of the role of nicotine as a gateway drug” to other drug addictions.

It is perhaps the privilege of a Nobel laureate (Eric Kandel is one of the recipients of the 2000 Nobel Prize in Physiology or Medicine) to write on any subject matter by ignoring the relevant work of most other prize-free scientists. Ironically, however, a laureate is awarded this prize precisely because many other scientists have recognized the importance and relevance of his/her own previous work.

Reading this Shattuck lecture, one is reminded of the novel “Pierre Menard, author of The Quixote” by Jorge Luis Borges. This novel illustrates how knowing the author of a text can dramatically impact our reading and interpretation of it. So I propose the following test for the interested reader. Please try to read this article as if it had not been co-authored by Eric Kandel. I bet that you will be surprised by how little this article contributes to the scientific question that it seeks to address.

On 2014 Sep 16, Serge Ahmed commented:

In this new Shattuck Lecture, Eric Kandel and Denise Kandel (K2) announce that they will let science speaks for itself about the role of “nicotine as a gateway drug” to other drug addictions and will not distort “what science does and does not tell us” about this controversial matter, as many others would generally do.

However, this paper is more about cross-sensitization between nicotine and other drugs in mice than about “nicotine as a gateway drug” to other drug addictions in human populations. Basically, K2 present evidence showing that forced pre-exposure to nicotine can enhance the proportion of individual mice that become sensitive to the stimulant and rewarding effects of a low dose of cocaine. In fact, after nicotine pre-exposure, a large majority of mice become sensitized to cocaine (i.e., up to 78-98% of mice). This proportion contrasts with the small minority of cigarette smokers who go on to develop cocaine addiction in human populations (i.e., 20%). This large discrepancy complicates the extrapolation between mice and humans but is ignored by K2. Would it imply that nicotine-exposed mice are more vulnerable to cocaine addiction than cigarette smokers? Or, more likely, would it indicate that nicotine-induced sensitization to cocaine per se should not be confused with cocaine addiction?

Research on cross-sensitization between different drugs, including nicotine and cocaine, in rats and mice were very popular among addiction researchers in the 80s and 90s. However, because drug sensitization is clearly not drug addiction, these studies have since been replaced by other, more valid animal models of drug addiction. This research is entirely ignored by K2. Thus, it remains to be demonstrated whether and to what extent initial nicotine self-administration in mice or rats can increase the proportion of individuals that develop more relevant behavioral features of cocaine addiction. Thus, we are back to the initial “scientific question of the role of nicotine as a gateway drug” to other drug addictions.

It is perhaps the privilege of a Nobel laureate (Eric Kandel is one of the recipients of the 2000 Nobel Prize in Physiology or Medicine) to write on any subject matter by ignoring the relevant work of most other prize-free scientists. Ironically, however, a laureate is awarded this prize precisely because many other scientists have recognized the importance and relevance of his/her own previous work.

Reading this Shattuck lecture, one is reminded of the novel “Pierre Menard, author of The Quixote” by Jorge Luis Borges. This novel illustrates how knowing the author of a text can dramatically impact our reading and interpretation of it. So I propose the following test for the interested reader. Please try to read this article as if it had not been co-authored by Eric Kandel. I bet that you will be surprised by how little this article contributes to the scientific question that it seeks to address.