True, false or utterly absurd? - Sydney Morning Herald

Inconclusive: the jury is still out on the efficacy of smoking cessation aids.

Do nicotine replacements help smokers quit?

As drug dependencies go, nicotine in cigarettes and other tobacco products ranks among one of the most addictive substances known to exist.

It's little wonder many of the million or so Australian smokers who attempt to kick their habit use nicotine patches, gum, lozenges or nasal sprays to ease withdrawal symptoms and increase their odds of quitting long term.

But in recent years, several studies (and many disillusioned smokers) have questioned the effectiveness of nicotine-replacement therapies, suggesting while these may help smokers overcome their nicotine addiction, they cannot combat the learnt behaviour of puffing on a ciggie.

While many factors determine whether a person becomes addicted to a drug, the chemical composition of certain substances increases the body's affinity to some more than others.

Nicotine, which is found naturally in tobacco, mimics one of the brain's neurotransmitters, a compound called acetylcholine that binds to receptors in the brain to release another neurotransmitter, the ''feel good'' chemical dopamine.

But nicotine's ''feel good'' effects are short-lived - about 40 minutes - which is why smokers reach for another cigarette about that time and, some suggest, why there are 25 cigarettes in a pack (there are 25 40-minute intervals in the 16 hours most people are awake).

The latest review of nicotine-replacement therapies by the independent, non-profit Cochrane Collaboration in November 2012 analysed the results of 150 clinical trials with more than 50,000 people and found the therapies increased a smoker's chance of quitting by 50 to 70 per cent. They found no type of therapy more effective than another, but heavy smokers needed higher doses.

But the very feature that makes controlled trials the gold-standard method for assessing a medical intervention - by controlling for other contributing factors - means they can be poor predictors of what happens in the real world. For example, participants are often paid to take part in studies and develop relationships with the researchers, both of which can motivate them to stick with the intervention.

With this in mind, surveys of former smokers can provide a more realistic picture of whether nicotine-replacement therapy offers smokers benefits over quitting cold turkey.

University of Sydney public health professor Simon Chapman says while several well-designed studies found a certain percentage of smokers kicked their habit with the aid of patches, other, more ''real world'' surveys showed the opposite effect, that most smokers quit without the aid of nicotine replacements.

''That means the jury's still out on the net effect of NRT,'' he says.