As states embrace legislation allowing the use of medical marijuana, investor interest in companies like GW Pharma (NASDAQ:GWPH), which is developing medicine based on the key chemical components of marijuana, has soared. 

But the marijuana plant may not be the only plant that could offer hope to people with chronic disease. Research studying nicotine suggests that it may have a medical benefit in patients with neurological disease like Alzheimer's.

If so, the use of nicotine as a treatment would challenge conventional thinking that ties the chemical to cancer and heart disease causing cigarettes.

Separating nicotine from smoking
More than 20 million people have died from causes related to smoking, according to the Surgeon General's annual report on the health consequences of smoking.

An intense focus on educating smokers in the risks of the disease has substantially reduced the number of cigarettes purchased in the U.S. over the past few decades. That's great news given that smoking causes 87% of lung cancer deaths, according to the Surgeon General.

Source: National Cancer Institute

But evidence suggests that nicotine, a stimulant chemical found in tobacco, may have some medical benefit -- just not when smoked as a traditional cigarette.

In a study conducted by Vanderbilt University's Center for Cognitive Medicine, Dr. Paul Newhouse found a link between nicotine and improved brain function in elderly patients with mild cognitive impairment, a potential precursor to Alzheimer's.

The study, which evaluated the use of nicotine patches on nonsmokers, showed that patients regained 46% of their age-adjusted normal long-term memory, based on memory test scores.

Meanwhile, patients in the study who didn't receive the patch saw their memory scores decline by 26%. Those results mirrored an earlier study conducted by Newhouse finding that Alzheimer's patients receiving nicotine intravenously also saw memory improve.

Those studies, while limited in size and duration (less than 70 people participated for just six months) may suggest that nicotine delivery systems, like the nicotine patch -- or conceivably e-cigarettes -- could have an intriguing role in slowing the progression of Alzheimer's. Of course, far more data is needed before any conclusions can be drawn, but it's an interesting potential opportunity. 

Changing perceptions
Bad perceptions of nicotine are likely to continue (particularly given its strong role in addiction), but there may be some interesting opportunities to have a conversation about potential benefits in specific disease areas. Scientific discovery has been changing how people view marijuana thanks to efforts by drug developers to create drug treatments based on THC and CBD, which are key marijuana cannabinoids.

For decades, cancer patients enduring chemotherapy induced nausea have been treated with Marinol, a synthetic version of THC developed by Solvay Pharmaceuticals and now marketed by AbbVie and a host of generic manufacturers.

More recently, GW Pharma has won approval for its first THC-based drug, Sativex, in more than 11 countries and while sales are still small, totaling just $13 million in the first quarter, the company is researching its use in other indications including cancer pain and diabetes.

Source: GW Pharma

Tobacco research by pharmaceutical companies could similarly help shift people's perception of nicotine.

AstraZeneca (NYSE:AZN), through a partnership with Targacept, a clinical stage company that was spun out of Reynolds Tobacco back in 2000, has been conducting various studies of small molecule drugs for a variety of disease, including Alzheimer's, by targeting nicotine receptors.

So far, results have been inconclusive. As a result, AstraZeneca opted out of its collaboration on TC-1734 in 2013. But a phase 2b trial of TC-1734 in Alzheimer's patients has continued with Targacept reporting last summer it had completed enrollment, putting Targacept on track to deliver data from this trial by mid year. Those trial results will be watched closely given that TC-1734 is being studied head to head up against the most commonly prescribed Alzheimer's treatment -- Eisai and Pfizer's Aricept, which posted $3 billion in annual sales prior to losing patent protection in 2010.

Nicotine's role in memory
Nicotine is a stimulant that activates cholinergic neurons. Those neurons are common in the central nervous system (the system responsible for everything from anxiety to memory) and die off in Alzheimer's patients.

Dr. Peter Whitehouse, a neurologist at Case Western Reserve University in Cleveland, was one of the earliest to research the role of nicotine receptors in memory and to suggest that stimulating nicotine receptors could potentially have a positive impact on patients with neurological disease.

Whitehouse, whose focus is on eldercare, thinks nicotine receptors may be a better target for research than current medicines like Aricept, which target neurotransmitters that affect memory loss differently than nicotine receptors.

But Whitehouse is also one of the first to admit that research in the area has yet to produce nicotine receptor medicine worthy of widespread use due to either poor efficacy or side effects. 

Fool-worthy final thoughts
So far, patients have either been given nicotine intravenously or via the patch. No research has been done yet in evaluating e-cigarettes, which deliver nicotine to the body inconsistently and may not produce similar positive effects in trials.

E-cigarettes may also prove to be a poor delivery system because their vapor, while arguably less toxic than cigarette smoke, still carries trace amounts of carcinogens like formaldehyde. 

"I would be concerned about them as a delivery device because they're unregulated and thus may have a whole variety of ingredients in them. Additionally, the dose delivery would not be uniform. I think it would be best to stick to delivery systems that we have some degree of confidence in and deliver similar doses over a period of time, " said Newhouse, who is hoping to conduct a national nicotine study in pre-Alzheimer's patients soon.