Giving up cigarettes ‘cold turkey’ or without cutting back first, could lead to relapses that make it even harder to quit, according to researchers at the University of Copenhagen.

"Regular smokers experience an almost dementia-like condition in the early hours after quitting, as suggested by brain scans," says Professor Albert Gjedde, neuroscience researcher at the Department of Neuroscience and Pharmacology, University of Copenhagen.

In the study, which was published in the Journal of Cerebral Blood Flow and Metabolism, Dr. Gjedde cites this uncomfortable sensation as being the culprit that keeps smokers going back for more cigarettes.

"Smokers drift back into abuse, perhaps not to obtain a pleasant effect -- that ship has sailed -- but simply because the withdrawal symptoms are unbearable," he says.

While nicotine is what makes cigarettes addictive, says Dr. Gjedde, smoking temporarily increases brain activity but after we stop, our brain's oxygen uptake and blood flow plummet even more, by as much as 17 per cent.

The effect of nicotine is comparable to that of other pharmacologically addictive drugs and Dr. Gjedde uses antidepressants as an example.

In time, says Dr. Gjedde, antidepressants cease their effect on patients, although sensations of overwhelming discomfort can come into play when treatment is discontinued -- just like what smokers experience.

Quitting smoking gradually can reduce dependency over time, yet it's not certain how much, and Dr. Gjedde says that smoking's effect on the brain is still not fully understood in many aspects.

"The new findings suggest that it may be a good idea to stop smoking gradually," says Dr. Gjedde, "simply to avoid the worst withdrawal symptoms that make it so difficult to stick to the otherwise very sensible decision to stop smoking."