Nicotine patches don't help smokers kick the habit and remain cigarette-free over the long haul, but it has positive effects on the brains of older people who are suffering from mild memory loss, new studies show.

A new study, published in the online edition of Tobacco Control and funded by the U. S. National Cancer Society, raises serious questions on the effectiveness of nicotine replacement therapy.

"Even though other well-controlled studies have shown that nicotine replacement therapy can be effective, our study looked at real-world use over the long-term," said study lead author Hillel Alpert, a research scientist with the Harvard School of Public Health's Center for Global Tobacco Control in Boston. "And in the real world, cigarettes are simply a very powerful addiction. And NRT is apparently not an effective replacement for that addiction."

Meanwhile, a separate study found that seniors suffering from mild cognitive impairment or MCI, could boost their mental abilities with a nicotine patch. Researchers led by Dr. Paul Newhouse, a professor of psychiatry and director of the Center for Cognitive Medicine at Vanderbilt Medical Center, said the patches also led to improvements in attention and mental processing but these effects weren't as strong as the impact on memory.

Aside from improving the brain's functions, here other things you probably do not know about nicotine.

Nicotine can change how your brain and your body function, thus it can both invigorate and relax a smoker, depending on how much and how often they smoke.

Nicotine initially causes a rapid release of adrenaline, the "fight-or-flight" hormone. Thus, nicotine can cause rapid heartbeat, increased blood pressure and rapid, shallow breathing, which are common effects of adrenaline.

Nicotine blocks the release of the hormone insulin, telling the cells to take up excess glucose from your blood. This means that nicotine makes people somewhat hyperglycemic, having more sugar than usual in their blood. Cigarette smokers think that nicotine curbs their appetite actually, their bodies and brain may see the excess sugar and down-regulate the hormones and other signals that are perceived as hunger.

Nicotine may also increase basal metabolic rate slightly, so that a person burns more calories than he would usually do even when just sitting around. But there is no health benefit from losing weight by smoking as nicotine can increase the level of bad cholesterol in the long run which can damage the arteries.