8. What further research might be needed?
The SCENIHR opinion states:
Although proposals for research recommendations were not part of the mandate of SCENIHR, we have found it useful to indicate some of the topics that were identified during the work on the opinion. It is evident that advanced studies on the action of nicotine and tobacco additives need considerable financial resources that are generally not available in public laboratories. Technological advances have been made in recent years that permit new information to be obtained, for instance on smoke composition and neural networks (functional neuroimaging). We propose either calls for European collaborative projects addressing questions about tobacco and additives or the creation of a European Institute for research on drugs of abuse. An improved knowledge in these areas would allow evidence-based regulation of the manufacture and marketing of tobacco products to be established. Among the proposed research areas are the following:
Smoke composition of tobacco products other than cigarettes
Very little is presently known regarding the composition of smoke emanating from cigars, cigarillos and waterpipes. Thus, knowledge necessary for assessing the potential of smoke constituents to facilitate inhalation of tobacco smoke and also the possibility for smoke to increase addiction is sparse.
The neurophysiological basis of tobacco addiction
It is suggested to determine, by neuroimaging studies, whether nicotine alone (e.g. given as pills) induces signals in the brain of dependent smokers that are different from non-smokers.
Furthermore, to perform experimental studies in vivo and in vitro (e.g. by neuroimaging, microelectrode arrays, neurochemical, and behavioural approaches) that investigate the influence of different tobacco additives on the addictive potential of nicotine. These studies are crucial to define the exact role of the multiple tobacco additives in the final high addictive potential of tobacco (in humans).
Importance of the level of different sugars for the addictive potency of tobacco products
Sugars are present in significant amounts in Virginia tobacco or are added in high quantities to Burley based tobacco products. It has been established that a high sugar content increases the attractiveness of tobacco products, but it has not yet been clearly demonstrated that sugars increase the addictive potency of tobacco products. It is, however, known that sugars generate numerous aldehydes upon heating, and scientific data indicate that these aldehydes increase the addictive potency of tobacco. Studies both in animals and humans are therefore required to establish whether the sugar content is related to the addictive potency of tobacco products.
Topics to be studied: (1) Relative efficacy of various sugars to generate aldehydes; (2) Mode of action; and (3) The capacity of different tobaccos (i.e. plain Burley tobacco, Burley tobacco enriched with sugars vs. Virginia tobacco) to form aldehydes and inhibit MAO in situ. Other compounds besides aldehydes and possible mechanisms other than MAO inhibition should also be considered to explain the high addictive potential of tobacco products.
It is necessary to perform innovative techniques such as neuroimaging to assess the attractiveness of tobacco additives objectively. The methods should be sufficiently sensitive to detect the contribution of a single additive added to a tobacco product.
Information on brands preferred by new smokers and the reasons for brand choice, focussed on tobacco additives
Certain typical UK brands are popular although no additives have been used in their manufacture, whereas popular continental brands contain many additives. The differences between these two types with respect to addictive potency should be investigated in comparable user groups. Comparison of use patterns across countries are not likely to give relevant information about the role of additives. Topics of research: (1) Comparison of the sugar content in different brands; (2) Comparison of the potency to generate aldehydes; and (3) Comparison of the addictive potency (measure the consumption pattern at individual level). The outcome provides the scientific rationale for the option to control sugars as tobacco additives and to limit their content in tobacco products.
It is also deemed necessary to determine what makes a specific brand attractive for new smokers. Is it the image, popularity, peer influence, taste, or other factors? In this context, epidemiological/sociological studies on trends (studies designed to evaluate the effect of additives on smoking behaviour and their role for initiation) can provide information on what can determine attractiveness.