Confirmed: Snus Use Protective for Parkinson’s Disease

Investigators in Sweden, Italy and the United States report that “non-smoking men who used snus had a substantially reduced risk of Parkinson’s disease…”

The research, published in the International Journal of Epidemiology (abstract here), combined data from seven Swedish cohort studies involving nearly 350,000 men.  Subjects were classified according to tobacco use and diagnosis of Parkinson’s disease (an illness of the nervous system affecting movement) over an average 16 years of follow-up.

The principal results are impressive:

“Among never-tobacco smokers, Parkinson’s disease risk in ever-snus users was lower than in never-users (pooled [hazard ratio, similar to relative risk] HR = 0.41, 95% [confidence interval] CI 0.28-0.61, for the fully-adjusted model).  Current-snus use was associated with a lower Parkinson’s disease risk than former use.  In addition, there was evidence of dose-response relationships such that moderate-heavy amount (pooled HR 0.41, 95% CI 0.19-0.90) and long-term current-snus users (pooled HR 0.44, 95% CI 0.24-0.83) had the lowest Parkinson’s disease risks.”

The bottom line: Current snus use, not former use, was strongly protective against Parkinson’s disease, with more protection from heavier and long-term use.

This is not the first such finding.  In 2009, I discussed (here) research from the American Cancer Society showing a similar strong protective effect (Relative risk, RR = 0.22, CI = 0.07 – 0.67) (abstract here).  Further, Parkinson’s may not be the only nerve illness for which smokeless tobacco and/or nicotine use is protective.  Snus users have a significantly lower risk for multiple sclerosis than nonusers of tobacco (here).  Nicotine has been found to improve performance in people with mild cognitive impairment, and it may also benefit those with Alzheimer’s disease (discussed here).

The current study represents a new era in Swedish snus research.  It was conducted by the Swedish Collaboration on Health Effects of Snus Use, “which brought together Swedish prospective cohort studies with detailed information on tobacco smoking and snus use.”

In the past, the snus research field was dominated by investigators at the Karolinska Institute; they published a series of studies that featured obvious technical problems and contradictions, and routinely found significant, small risks.  I documented these flawed studies in professional journals and in my blog (here, here, here, and here).

It is my hope that the Swedish Collaboration, with investigators from multiple universities in Sweden and beyond, will produce valuable, unbiased research on the health impact of snus use.

Snus Nicotine Lowers Risk for Multiple Sclerosis, May be Therapeutic for Other Nerve Disorders

New research published in Multiple Sclerosis Journal (abstract here) and authored by Anna Hedström of Stockholm’s Karolinska Institute of Environmental Medicine confirms that snus users have a significantly lower risk for multiple sclerosis (MS) than nonusers of tobacco.  I discussed the researchers’ earlier findings on this subject five years ago in this blog (here).

Hedström’s study is based on some 7,900 Swedes with MS and 9,400 controls.  Compared with never users of tobacco, snus users had a lower risk for MS (odds ratio OR = 0.75, 95% confidence interval, CI= 0.63 – 0.90).  Hedström also showed an increased effect at higher duration-dose levels of snus.  For example, users with greater than ten packet-years (the number of snus doses per day and years of use) had an OR of 0.45 (CI= 028 – 0.68).  Smokers had modestly increased risk (OR= 1.49, CI= 1.40 – 1.59), a finding that is similar to that reported in Hedström’s previous study.

Scientific research is methodically unveiling the benefits of nicotine and smoke-free tobacco use with respect to degenerative brain diseases.  A finding that nicotine may improve performance in people with mild cognitive impairment (discussed here), has resulted in calls for more research on nicotine’s effect on dementia (reference here).

The impact of nicotine/tobacco use on Parkinson’s disease is well documented.  An American Cancer Society study (here) provides clear evidence that smokeless tobacco use may be protective for Parkinson’s disease (RR = 0.22, CI = 0.07 – 0.67).  In fact, nicotine is being discussed as therapy for this disorder (here, here  and here).

Alzheimer’s disease is the sixth leading cause of death in the United States, and Parkinson’s disease is the fourteenth.  The role of nicotine and smoke-free tobacco in reducing risk of or treating these disorders is of significant import.

Nicotine Improves Cognitive Performance

Six months’ treatment with nicotine produces measurable improvement in patients with amnestic mild cognitive impairment (MCI), a decline in cognition and function that falls short of dementia or Alzheimer’s Disease, according to research published in the journal Neurology (abstract here) by Dr. Paul Newhouse at the University of Vermont and colleagues at Vanderbilt, Georgetown, Duke and the University of California San Diego.

Newhouse et al. enrolled 74 non-smoking subjects and gave about half of them 15 mg. nicotine patches for six months (the other half got placebo patches). The results:

“This study demonstrated that transdermal nicotine treatment for 6 months improved cognitive performance in subjects with amnestic MCI…Several secondary cognitive measures showed significant nicotine-induced improvement including psychomotor speed and attention on several tasks as well as significant effects on long-term memory seen in both the paragraph recall task and computerized word recall task…There were trends for improvements in a number of other cognitive measures…There was no evidence for loss of cognitive effects over time. The primary clinical outcome, the Clinical Global Impression by the clinician, did not show significant improvement; however, patients and their informants did report nicotine-induced improvements.

“This study found that transdermal nicotine over 6 months is a safe treatment for nonsmoking subjects with MCI…measures of attentional, memory, and psychomotor performance did show an effect of nicotine and this finding provides strong justification for further treatment studies of nicotine for patients with early evidence of cognitive dysfunction.”

This study extends the results from previous reports. According to Newhouse et al.:

“Cognitive improvement is one of the best established therapeutic effects of nicotine (PubMed Reference here). In human studies, nicotine improves performance in smokers on cognitively demanding attentional tasks (References here, here and here). In clinical studies, memory improvement was initially seen with IV nicotine in subjects with Alzheimer’s Disease (Reference here). Others have also found nicotine administration by subcutaneous injection or transdermal patch to improve
cognitive function in Alzheimer’s Disease (References here, here and here; one reference not in Pubmed).”

This research confirms that nicotine improves cognitive performance in people with MCI, and it may also benefit those with Alzheimer’s Disease. For those who would demonize nicotine, this should be highly informative.