Does advertising nicotine patches increase the smoking rate?

I'm currently reading The Logic of Life by Tim Harford. He mentions something about the advertising of nicotine replacement therapy (NRT) which I found interesting (p. 59).

Economists have also found that advertising for nicotine patches and gum seems to encourage non-smoking teenagers to smoke. That's easy to explain if teenagers are rational: the advertisements tell them that there are new ways to help them quit, so rationally it is less risky to start the habit.

It does make sense. If people are told there is an easy way to quit, they will be less tentative about starting. The study he refers to is this:

The Effect of Nicotine Replacement Therapy Advertising on Youth Smoking

The results indicate that NRT advertising has no effect on participation but increases smoking by youth who do smoke. The elasticity of smoking with respect to NRT advertising is about .10 and the elasticity of smoking with respect to price is about -1.03. Since average youth smoking is about 5.77 cigarettes per day, an increase of 10 percent in NRT advertising would increase this average to about 5.82 cigarettes per day. It is also estimated that a ban on NRT advertising would be equivalent to a 10 percent increase in cigarette prices.

You will notice that this study doesn't quite confirm what Harford is saying. NRT advertising makes smokers smoke more but "has no effect on participation" ie. it doesn't get non-smokers to start. 

This proposition was tentatively confirmed in an earlier study, which concluded:

...those exposed to NRT ads reported stronger perceptions about the ease of quitting, but non-susceptible non-smokers primarily drove this difference. This study suggests that exposure to NRT and Zyban® advertising in an experimental context does not reliably influence youth smoking-related beliefs, especially those vulnerable to becoming regular smokers.

But if NRT ads make people thing it is easy to quit, why wouldn't this perception affect those who are "vulnerable to becoming regular smokers"? You would expect them to be the most affected. How do we even work out who is "vulnerable" and who is "non-susceptible" any way?

The picture is clouded further by the fact that Melanie Wakefield was involved with both of these studies. Wakefield is Deputy Editor of the journal Tobacco Control, which has always been well-disposed to pharmaceutical nicotine. Indeed, one of her other studies on NRT was sponsored by GlaxoSmithKline.

The question of whether NRT advertising increases the smoking rate is, therefore, intriguing but unresolved. I dare say it will remain unresolved for as long as the pharmaceutical industry funds anti-smoking groups, conferences and research. At a time when ASH are calling for a 5% increase in cigarette taxes, it is interesting that research indicates that a ban on NRT ads would have the same effect as a 10% increase in cigarette taxes. But don't expect to hear pharmaceutically funded pressure groups like ASH calling for that any time soon.