Is nicotine getting a bad rap?

By Margo White In Health

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25th February, 2012 1 comment

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Nicotine is a chemical compound found naturally in the tobacco plant, and widely assumed to be responsible for people’s addiction to cigarette smoking. Yet nicotine is only one of 4000 different chemicals in tobacco smoke, many of which have yet to be characterised. The Listener interviewed Katie Brennan from Victoria University’s School of Psychology, whose research interests include behavioural pharmacology and drug addiction, and found that nicotine is not as guilty as often charged.

How does nicotine affect the brain?
Nicotine reaches the brain between seven and 10 seconds after tobacco smoke has been inhaled. It can then bind to numerous types of brain cells in different regions of the brain, which results in the release of a variety of brain chemicals, such as dopamine, serotonin and acetylcholine. Dopamine is associated with reward and addiction, serotonin with mood and appetite, while acetylcholine affects cognitive function. This is why nicotine can produce a stimulant-like effect in the brain, increasing arousal and learning, and can alter memory storage and retrieval.

Because there is some release of serotonin and dopamine, nicotine can have a positive effect on mood and be mildly rewarding. But pure nicotine is a mild stimulant and not very rewarding compared with cocaine and amphetamines. Drugs such as methamphetamine (or P) release 10 or more times the dopamine and serotonin that nicotine does. This has been shown in both people and laboratory animals – given a choice, rats always choose cocaine over nicotine.

How addictive is it?
Not very. There are almost no reports of people becoming hooked on nicotine replacement therapies, such as patches, gum or nasal sprays. It’s possible that these modes of nicotine delivery don’t accurately mimic the way nicotine is delivered by smoking. For example, nicotine absorption through the skin (patches) or the mouth (gum) reaches the brain much later than nicotine delivered by a cigarette. This is why e-cigarettes that contain nicotine have not been approved by the Food and Drug Administration in the US or Medsafe in New Zealand as a medicine that can be used to treat smoking.

The e-cigarette is designed to deliver vaporised nicotine in a way that combats the craving to smoke, but since it’s relatively new, no research has been done to determine how addictive it is, or whether people could get addicted to e-cigarettes and move on to more harmful tobacco cigarettes. Even so, I believe that the e-cigarette provides a better replacement than anything else that’s available, and I don’t believe it will be highly addictive, either. However, when combined with the thousands of substances found in tobacco and smoked, nicotine is very addictive. This suggests the other compounds could contribute to the rewarding and addictive pharmacological properties and also that environmental and social influences related to the act of smoking contribute greatly to the habit becoming ingrained.

So if nicotine isn’t to blame, what is?
This is what I’m researching. There are substances in tobacco – such as harman, norharman, acetaldehyde, anabasine, nornicotine, anatabine, cotinine and myosmine – that are suspected to boost the effects of nicotine on serotonin/dopamine/acetylcholine systems, and could also produce long-lasting changes that might increase people’s susceptibility to relapse. My lab team is looking at the rewarding features of an aqueous tobacco solution compared with pure nicotine to see whether there is any hard evidence that these other tobacco compounds have any major role.

An increasing number of studies suggest nicotine could be effective in treating neurological disorders, such as Parkinson’s and Alzheimer’s.

Yes, and this makes sense to me. It has been reported that an extremely high number of patients with schizophrenia are smokers, and it has been suggested that nicotine can “settle” imbalances in brain chemical systems and even stimulate the release of any chemicals that are lacking in certain areas. Since nicotine is very mild compared with other stimulant drugs, it would be less likely to cause wild fluctuations in the brain’s chemical balance – unlike methamphetamine, which will make symptoms 100 times worse.

Alzheimer’s disease is a slow degeneration of the brain that is not really specific to any one region. The brain chemical acetylcholine is involved in cognitive function, and Alzheimer’s patients are often given a drug that slows the breakdown or prolongs the presence of acetylcholine in the brain. Nicotine directly stimulates acetyl choline systems and is very mild, so it’s not surprising, or alarming, that it is being trialled as a treatment option.

FARMS AID IMMUNITY

Photo Patrick O'Sullivan/HBT

Many studies have suggested that growing up on a farm reduces the chance of developing allergies, but it hasn’t been clear whether people who are prone to allergies are less likely to live on farms, or the farm environment promotes protection against allergies. Now researchers from the University of Bristol have demonstrated it’s likely to be the latter, at least in piglets, some of which were nursed by their mothers on a farm while their siblings spent their early life in an isolator unit under extremely hygienic conditions and were fed formula milk. The farm-raised piglets had significantly higher numbers of T lymphocytes, the regulatory cells that pacify immune responses and inflammation than those raised in the isolator unit.

ANTIDEPRESSANT CLEARED

Treating young patients with the antidepressant fluoxetine (eg, Prozac) neither increases nor decreases suicidal thoughts or behaviour, a study published in the Archives of General Psychology has found. In 2004, concerns that antidepressant drugs increased suicidal thoughts and behaviours in young patients prompted the US Food and Drug Administration to issue a rare “black box warning”.

A LOT’S IN A NAME

People with names that roll off the tongue easily have a better chance in life than those who don’t, a study in the Journal of Experimental Social Psychology suggests. The researchers found that people with more pronounceable names were more likely to be favoured for political office and job promotions – political candidates with easy-to-pronounce names were more likely to win, and attorneys with more pronounceable names rose more quickly to superior positions in the firm.

25th February, 2012 1 comment

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One Response to “Is nicotine getting a bad rap?”

  1. Dianne Macdonnell Mar 16 2012, 1:46am

    Really appreciated your article, Feb 25, Margo. Have used nicotine-delivering e-cigs for about 2 years; still smoking some tobacco but reducing. Purse and body can't afford to continue with tobacco! E-cigs are great. Cheaper, great tastes available in the nicotine juice. There is seriously no odour, no smoke, no butts, no ash. People are amazed when I "demonstrate" an e-cig for them.
    Look forward to the results of your research into the addictiveness of nicotine when taken in through tobacco. Cheers, Dianne
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