Effects of nicotine on the central nervous system

Patching up

Brad successfully kicked a long-time cigarette smoking habit in June of 1990. As with most everyone who quits smoking, he was looking forward to improved health in return for his hard won victory. Instead, just five weeks later, he was diagnosed with multiple sclerosis.

Right from the beginning, Brad had a hunch that the sudden appearance of the MS symptoms was somehow connected to his break with cigarettes. But when he opened the subject with his doctor and other healthcare professionals, his hunch was always dismissed as illogical. I mean, how could there be ANY downside with kicking the habit, right?

Then in 1998, Brad picked up a copy of the Wall Street Journal and read an article about R.J. Reynolds Tobacco Company scientists who were studying the effects of nicotine on central nervous system (CNS) diseases such as Parkinson’s disease, Alzheimer’s disease, and MS.

Seems they wouldn’t have thought Brad’s hunch was so illogical.

Central nervous mysteries

When Brad read the Wall Street Journal article in ’98, he didn’t need to consult any doctors or researchers. He began using an over-the-counter nicotine patch immediately. The patch helped improve the mobility in his hands and upper body, but after a couple of years became less effective and he stopped using it. He now feels strongly that if he had started using the patch when he was first diagnosed, he would have been able to have more control over the symptoms. But he doubts that the infusion of nicotine could have helped to significantly change the course of the disease.

Nicotine therapy. Those are two words I never expected to see side by side. But there are a number of research projects currently underway that, if successful, could one day bring nicotine into the mainstream as a therapy to help control various CNS disease symptoms.

I’ve noticed, however, that MS is mentioned in discussions of nicotine therapy infrequently. References to Parkinson’s disease, Alzheimer’s disease, Tourette’s syndrome, attention-deficit hyperactivity disorder, and depression are the most common health issues likely to be successfully treated with nicotine. Brad believes that the complexity of MS may be the reason it’s often left off that list. With Parkinson’s disease, for instance, researchers have a clearer idea about the mechanism of the disease – where it originates in the brain, and how it responds to treatments. Comparatively, MS is an enigma – far more difficult to understand and treat.

Into the maze

So at this point, what is known about nicotine and its effect on disorders of the central nervous system?

Start with acetylcholine, a biochemical neurotransmitter that creates nerve impulses in neurons. For the nervous system and muscles to function properly, acetylcholine has to find special receptors in the neurons. One of those receptors is called a nicotinic receptor, and it responds to both acetylcholine and nicotine. When nicotine is introduced into the system, the number of nicotinic receptors increases. Alzheimer’s patients, for instance, are believed to suffer from a loss of nicotrinic receptors. This impairs nerve impulses, resulting in memory lapses and problems with other brain functions.

More than two decades ago, research at Georgetown University showed that nicotine can also protect neurons against damage and death. The problem is that nicotine affects a wide variety of neurotransmitter systems. So while it may be doing good things in some areas, it also increases blood pressure and heart rate. This is one reason why quite a bit of nicotine research is focused on the development of nicotine formulas designed to be selective in their effects on the different varieties of nicotinic receptors.

Which is much easier said than done. It’s as if researchers were electricians, sorting through tens of thousands of individual circuits, looking for the one that performs a very specific task, and then trying to enhance that single circuit without affecting any of the others. But as daunting as that research might be, it continues in earnest, because if a synthetic nicotine that targets a single type of receptor can be developed, it can also be patented. That’s why a number of major pharmaceutical companies are currently devoting huge resources toward the development of a nicotine drug.

Something tells me this will not be the last e-Alert on this topic.

No smoking

If Brad had not successfully quit smoking on that June day in 1990, he would still have developed multiple sclerosis. He might have delayed the onset, but eventually it would have overcome the effect of the nicotine. Which brings us to two important points emphasized by the handful of researchers who have been studying nicotine for more than 20 years: 1) Nicotine may help treat CNS diseases, but it cannot cure them; and 2) This research should not in any way be taken as an endorsement of tobacco smoking. Without question, the negative effects of smoking far outweigh any positive effects that nicotine might have.

To Your Good Health,

Jenny Thompson
Health Sciences Institute