Smokers at Lower Risk of Parkinson’s, Long-term Study Finds

smoking and Parkinson's

Current or past tobacco smokers are at lower risk of developing Parkinson’s disease than lifelong non-smokers, a long-term study of doctors in the U.K. reports.

How smoking might protect a person against Parkinson’s, however, remains poorly understood. The many known health risks of tobacco smoking also far exceed “any protective effect,” its researchers caution.

The study, “Tobacco smoking and the risk of Parkinson disease A 65-year follow-up of 30,000 male British doctors,” was published in the journal Neurology.

Smoking is a well-known risk factor for cardiovascular diseases and many cancers, among other ills. But with Parkinson’s disease, it appears to exert a protective effect.

Previous studies have suggested that Parkinson’s incidence is inversely associated to smoking, with one study reporting that smoking was associated with a 60% lower risk of Parkinson’s.

But the link between smoking and Parkinson’s incidence is not well understood, as data on smoking habits are usually collected after disease onset, which is susceptible to bias. The number of Parkinson’s cases and length of follow-up duration is also limited, making conclusions difficult.

Researchers at the University of Oxford followed male doctors over 65 years to investigate the risk of Parkinson’s disease associated with smoking habits, the amount of tobacco smoked, and the duration of effects among ex-smokers.

Their analysis included 29,737 doctors, all members of the British Medical Association. Data on smoking habits were collected in seven self-completed questionnaires from 1951 to 1998.

Participants were asked to classify themselves as current tobacco smokers, ex-smokers, or those who have never smoked. Questions addressed their smoking habits: age at starting to smoke, amount smoked daily, and type of tobacco.

Researchers observed that the percentage of current smokers declined markedly over the study. At its start in 1951, about 67% of doctors (age 65 to 69) were smokers. This number dropped to 8% by 1998, the last year of follow-up. The percentage of those classified as cigarette smokers also decreased, from 63% in 1951 to 33% in 1998.

Specific cause of death was monitor through November 2016.

Between 1951 and 2016, participants were followed on average for 35 years. Of 25,379 deaths registered from 1961 to 2016 (the first 10 years of follow-up were excluded), 283 were attributed to Parkinson’s disease.

The crude death rate from Parkinson’s was lower for current smokers (30 per 100,000 person-years) compared to non-smokers (46 per 100,000 person-years). Of note, crude death rate is the total number of deaths of residents in a specified geographic area, divided by the total population for the same area.

Next, researchers modeled how smoking habits were associated to Parkinson’s risk at the start of follow-up (baseline model, the year 1951) and then periodically after each survey questionnaire (the updated model).

Results showed current tobacco smoking was inversely linked to Parkinson’s risk at baseline and in the updated model.

At baseline (1951) doctors classified as current smokers had a 30% lesser risk of PD compared to those who never smoked. In the updated model, current smokers had a 40% lower disease risk compared with never smokers.

Parkinson’s risk was also found to depend on the daily amount smoked. A statistically significant inverse correlation (higher daily amount, lower risk) ­in both baseline and updated models was seen between the amount of daily tobacco smoked and Parkinson’s incidence.

Doctors who quit smoking for 10 or more years had a 14% lower Parkinson’s risk than those who had never smoked; those who had quit smoking for nine or few years had a 29% lower risk.

The mechanisms underlying the observed inverse relationship are still not fully understood. Some argue that nicotine may have neuro-protective properties by stimulating the release of dopamine — the brain chemical lacking in Parkinson’s patients — but other tobacco compounds may also play a role.

The researchers caution that “the adverse effects of smoking on risks of vascular and respiratory diseases, neoplasms [cancers], and other noncommunicable diseases for which tobacco is the chief risk factor greatly exceed any protective effect of current tobacco smoking on the risk” of Parkinson’s.

Doctors who died of causes other than Parkinson’s did so at younger ages, a mean of 77, than did those who died of Parkinson’s (a mean age of 82), the study noted.

“The present report demonstrates a causally protective effect of current smoking on the risk of PD [Parkinson’s disease],” the researchers concluded, adding that future studies to understand the mechanisms underlying such a protective effect “may be worthwhile and may contribute to a better etiologic understanding of PD.”

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Study Urges Activism to Help Prevent Emerging Parkinson’s Pandemic

Parkinson's pandemic

A “PACT” formed by the Parkinson’s community — to prevent, advocate for increased resources, care for all those affected, and treat with new therapies — may help prevent a Parkinson’s pandemic, according to a review study.

The study, “The Emerging Evidence of the Parkinson Pandemic,” appeared in the Journal of Parkinson’s Disease.

Parkinson’s is the fastest-growing neurological disorder in the world, expected to double from 6.2 million to more than 12 million patients by 2040. Similar to pandemics of infectious diseases, Parkinson’s is increasing in every region of the world, though shifting from the West to the East mainly because of changes in aging and industrialization.

“By 2040, we can truly talk about a pandemic that will result in increased human suffering, as well as rocketing societal and medical costs,” Patrik Brundin, MD, PhD, one of the study’s guest editors, said in a press release. “How can the community be made aware of this scenario and implement changes in research priorities and care programs to lessen the burden of the upcoming pandemic?”

Aging populations — particularly a rapid rise in people older than 65 — and increasing life expectancy are two of the contributing factors to the rise in Parkinson’s. According to a 2018 study, increased life expectancy will extend the survival of 65-year-old Parkinson’s patients in France by nearly three years between 2010 and 2030, increasing disease prevalence by 12%. The number of people with advanced Parkinson’s is also expected to rise.

As smoking has been associated with a 40% lower risk of Parkinson’s, the current decline in smoking rates may also result in greater disease incidence. A recent study estimated that diminishing smoking rates in the U.S. may boost Parkinson’s incidence by 10% above projections that account for aging only.

Byproducts of industrialization — including specific pesticides (such as paraquat), solvents (such as trichloroethylene) and heavy metals — have also been linked to Parkinson’s. In China, a country with rapid industrialization, the prevalence of Parkinson’s increased more from 1990 to 2016 than in any other country. The ongoing use of these products in large quantities may accelerate the increase in cases.

Overall, “assuming a 12% increase due to increasing longevity, a 10% increase due to decreasing smoking, and that about half (10%) of the observed increase in age-adjusted prevalence rates persists due to environmental factors, the burden of [Parkinson’s] could exceed 17 million by 2040,” researchers said.

Unlike most diseases whose burden lessens with improving socioeconomic levels, disability because of Parkinson’s disease increases with income per capita and education. Besides patients, caregivers are also affected by the disease. Parkinson’s is further associated with a growing economic burden, currently directed at institutional care in the U.S.

Activism has played a key role in confronting pandemics of polio, breast cancer, and HIV in the past century, leading to effective prevention, more resources, better care, and new therapies.

“Following these examples,” the researchers proposed, “those with and at risk for [Parkinson’s] can form a “PACT” to prevent, advocate for, care, and treat the disease.” This would involve reducing or eliminating the use of chemicals known to boost Parkinson’s risk, securing more funding to better understand its root causes and to expand new care models, as well as develop new and effective therapies.

The Parkinson’s pandemic “is preventable, not inevitable,” researchers emphasized.

“We hope that this article will raise awareness of the challenge and form the basis for a community-led response to address one of the great health challenges of our time,” said Bastiaan R. Bloem, MD, PhD, a study author from the Radboud University Medical Center in The Netherlands.

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Cancer Patients Have Lower Risk of Developing Parkinson’s Disease, Study Suggests

cancer, Parkinson's risk

Cancer patients appear to have a lower risk of developing Parkinson’s disease, even when taking into account important risk factors and overall survival, a study has found.

The study, “Cancers Preceding Parkinson’s Disease after Adjustment for Bias in a Danish Population-Based Case-Control Study,” was published in Neuroepidimiology.

Previous studies have shown that cancer patients are less likely to develop Parkinson’s during their lifetime than the general population. However, it is unclear whether this could be caused by the negative association between Parkinson’s disease and smoking, when, for many cancers, smoking is a known risk factor, or simply by the fact that most cancer patients do not survive long enough to reach a stage in which they are more likely to develop Parkinson’s.

Researchers at the University of California Los Angeles carried out a large population-based case-control study in Denmark (PASIDA) to investigate if cancer correlated with a lower risk of Parkinson’s disease, even after normalizing important risk factors, such as smoking, physical activity, and survival bias.

The study involved a total of 1,813 patients with Parkinson’s disease and 1,887 age- and sex-matched individuals without Parkinson’s used as controls.

Demographic analysis showed the percentage of non-smokers was higher in the group of Parkinson’s patients (49.6%) than in controls (35.3%). Conversely, the incidence of cancer was lower among Parkinson’s patients (3.8%) than in controls (4.2%), a difference that was even more pronounced when comparing the incidence of smoking-related cancers (1.7% versus 2.2%).

Apart from skin and breast cancer, further analysis showed a negative correlation between Parkinson’s disease and all types of cancers, including those related and not related to smoking. Even after normalization for risk factors and cancer patients’ survival bias, the negative association between Parkinson’s disease and cancer remained the same.

“Since PD [Parkinson’s disease] cases stop smoking many years prior to PD diagnosis, one might say that ‘PD prevents smoking’ and thus reduces the risk of smoking-related cancers and mortality. [However,] in PASIDA adjustment for pack-years of smoking did not change the observed associations between cancer and PD, which suggested that smoking is unlikely to be a strong confounder between cancer and PD,” the researchers wrote.

“In conclusion, our study suggested a lower frequency of most cancers preceding PD diagnosis after adjustment for major lifestyle factors. Our bias analysis indicated that survival bias minimally impacts the observed associations,” they added.

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Physical Activity, Coffee, Moderate Alcohol Consumption Protect Against Disease Progression, Study Reports

coffee, alcohol, lifestyle factors

Physical activity and participation in competitive sports, as well as coffee, caffeinated tea or moderate alcohol consumption before diagnosis, protect against worsening motor and cognitive function in Parkinson’s patients, according to a new population-based study.

In contrast, smoking and heavy alcohol consumption — or never consuming alcohol — correlated with higher risks of mortality and cognitive and motor decline.

The research, “The Association Between Lifestyle Factors and Parkinson’s Disease Progression and Mortality,” was published in the journal Movement Disorders.

Lifestyle factors such as coffee and moderate alcohol consumption, physical activity, and cigarette smoking have been linked with lower risk of Parkinson’s disease. Whether they affect disease progression remains undetermined, although small studies have shown that smoking and drinking coffee do not affect motor progression in Parkinson’s.

In turn, nonpaharmacologic approaches such as physical activity may benefit physical functioning, balance and gait, as well as protect against dementia.

Researchers at the UCLA Fielding School of Public Health and the David Geffen School of Medicine, in Los Angeles, California, assessed whether diverse lifestyle factors before a Parkinson’s diagnosis in adults affect motor progression, cognitive decline, and survival.

A total of 360 patients were enrolled within three years of diagnosis (average 2.1 years), as part of the population-based Parkinson’s Environment and Gene study in central California. The patients lived in one of three central California counties — Kern, Fresno or Tulare — and were followed from 2001 to 2016.

From the 252 patients not lost to follow-up (mean follow-up 5.3 years; 64 patients deceased, six were too ill, 17 withdrew, and 21 could not be contacted), 244 individuals — 139 men, mean age at diagnosis 66.9 years, mean duration of disease at baseline 2.1 years — provided data for analysis of disease progression.

The team also included 341 control participants from the same communities for analysis of mortality, who had been living in California for at least five years.

Telephone interviews were conducted to obtain self-reports of history of smoking, caffeinated coffee/tea or alcohol (beer, wine and liquor) consumption, overall physical activity level, and participation in competitive sports.

The participants were asked to report at what age they started and stopped drinking the beverages, as well as their average consumption per day during four age groups: 18-24, 25-44, 45-64, and 65 years or older.

Also, patients were asked about the average number of days per week and hours per day they participated in mild, moderate, or vigorous physical activity at the same age groups. Participation in competitive sports also was addressed, including basketball (20.6% of participants), baseball (18.1%), football (18.1%), track and field (12.5 %), and softball (8.3%).

Physical examinations were performed at each visit to assess motor function — Hoehn & Yahr (H&Y) stages — and cognition, with the Mini-Mental State Exam (MMSE). Cognitive decline was defined as a 4-point decrease from baseline MMSE examination.

In total, 209 patients (58%) and 67 controls (20%) died during follow-up. Fifty of the 244 patients (21%) assessed for progression experienced a 4-point or greater decline on the MMSE, while 77 (32%) progressed to H&Y stage 3 — transition from mild to moderate motor dysfunction, with loss of balance — or worse.

Coffee, caffeinated tea, moderate (below the median drinks per day), beer or liquor consumption, and participation in competitive sports were protective against mortality. In contrast, smoking and never drinking coffee or alcohol correlated with increased risk of mortality. Of note, the higher risk with smoking contrasts with prior studies showing protection against disease onset, the scientists noted.

In controls, alcohol and coffee consumption also were protective, while smoking conferred greater mortality risk.

The data further showed that engaging in competitive sports was associated with a history of head trauma in Parkinson’s patients, but not in controls. Head trauma also was linked with shorter time from diagnosis to death in this subset of patients.

Ever coffee consumption, participating in competitive sports and physical activity were protective against both motor function worsening and cognitive decline. Compared to moderate drinkers, patients who never drank liquor and those who drank more heavily were at greater risk for motor dysfunction. Also, never drinking and current cigarette smoking were associated with increased risk of cognitive decline.

Comparing patients who never drank coffee to those who have ever drank it, the findings also showed that never consuming coffee was associated with younger age at diagnosis (62.6 vs 67.6 years), longer disease duration at baseline (2.7 vs. 1.9 years) and less weekly alcohol consumption at some point (44% vs 69%).

“Although replication is needed,” researchers wrote, “our study suggests that multiple lifestyle factors potentially modify the rate of symptom progression.”

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Study Links Smoking, Reduced Parkinson’s Risk, But Comes with Caveat

Parkinson's and smoking

Smoking more cigarettes or for a longer time is associated with a decreased risk of developing Parkinson’s, according to a population-based study.

A reduced risk was also seen in people exposed to passive smoking compared with those who had never smoked.

However, the scientists cautioned that rather than encouraging people to smoke, the findings warrant further research into which compound in tobacco confers this effect.

The study, “Exploring causality of the association between smoking and Parkinson’s disease,” was published in the International Journal of Epidemiology.

The link between smoking and a reduced risk for Parkinson’s is supported by substantial evidence in men and women, and has included cigarette, pipe, and cigar smoking, as well as using smokeless tobacco. Also, children of smokers have shown a lower risk for developing the disease.

However, researchers have recommended considerable caution in interpreting this association as protective. They have been studying a potential effect of personality, in particular whether a low-risk-taking personality would be a confounder, especially if induced by dopamine shortage — a Parkinson’s hallmark — which may make it easier to quit smoking. In this regard, a link between passive smoking and protection from Parkinson’s — which is not susceptible to different personalities — could not be determined.

To better understand this correlation, researchers from Queen Mary University of London, Imperial College London and University of Campania Luigi Vanvitelli, in Italy, analyzed the link between Parkinson’s risk and smoking duration, amount and time since quitting smoking. They looked at a potential delaying effect, smoking patterns among current and former smokers, the association with passive smoking, and the consistency across clinical subtypes.

The study included 220,494 people participating in NeuroEPIC4PD, a prospective European population-based study in 13 centers from eight countries. A total of 715 cases of Parkinson’s (mean age at recruitment 61.4 years, age at onset 67.5) were analyzed.

Data on smoking habits were collected at recruitment, including whether participants were never, former or current smokers, their age when they started smoking and when they quit, and number of cigarettes per day at different ages.

The results showed that, compared with people who had never smoked, former smokers had a 20% lower risk and current smokers a halved risk for developing Parkinson’s during follow-up (12.8 years).

Smoking more cigarettes and for a longer period of time were also associated with a lower risk of developing the disease, as the risk in people smoking 12 or more cigarettes a day or for longer than 30 years was about 55% lower compared to those who had never smoked.

Smoking correlated with reduced disease risk in both mid-age and late-onset Parkinson’s, as well as in tremor-dominant and akinetic-rigid (slowed movement, muscle stiffness, postural instability, gait impairment) Parkinson’s. Also, the risk did not vary over the follow-up period, which argues against a delaying effect of smoking on Parkinson’s onset, the team observed.

Exposure to passive smoking at home or work was also linked to lower risk, as passive smokers were 30% less likely to develop the disease than non-exposed individuals.

“In conclusion, the present findings are consistent with a protective effect of smoking on the risk of [Parkinson’s],” scientists stated.

“Our discovery is incredibly important from a scientific point of view and should prompt basic science research aimed at identifying the agent responsible for this effect found in tobacco,” Valentina Gallo, MD, PhD. the study’s first author, said in a press release. “Hopefully this will give insight for preventive treatment options.”

“However, no one would ever be advised to use smoking as a preventive treatment for Parkinson’s based on this research, because of the disastrous effects we know smoking has on people’s general health,” Gallo added.

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Specific Tremors, Asthma Meds Not Linked to Parkinson’s Risk, Large Study Suggests

Researchers may have discovered why certain tremors and asthma medications increase the risk of developing Parkinson’s disease.
Their findings suggest they were caused by the underlying clinical indications that led physicians to prescribe these medications in the first place — tremors and smoking-related lung conditions — rather than the medications themselves.
Their study, “β2-adrenoreceptor medications and risk of Parkinson disease,” appeared in the journal Annals of Neurology.
A previous study, using mouse models and nationwide pharmacy data from Norway, suggested that using therapies that target the beta-2 adrenoreceptor — which is found in cells of the lung, brain, heart, skeletal muscle, and immune system — can influence the risk of developing Parkinson’s.
That study suggested that medications known to suppress the beta-1 receptor — such as propranolol, a first-line treatment for tremors — doubled the risk of Parkinson’s, while those known to activate the receptor —such as salbutamol, usually given to treat asthma and other lung diseases — decreased the risk by a third.
Researchers at Washington University School of Medicine in St. Louis, Missouri, have now evaluated whether the underlying clinical indications for the use of these medications – tremors and lung conditions – could explain these associations.
Their hypothesis was based on the fact that tremors are among the early signs of Parkinson’s, and that lung disease is more frequent in smokers than non-smokers, with several studies suggesting a link between nicotine and a lower risk of Parkinson’s.
The team analyzed the Medicare data of 28,295 U.S. Parkinson’s patients and 52,324 healthy individuals. They evaluated the effects that three medications which block the beta-2 receptor (propranolol, carvedilol, and metoprolol) and primidone (used to treat tremors) or of salbutamol and inhaled corticosteroids used for similar lung conditions — had on the risk of developing Parkinson’s.
They found that use of propranolol prior to Parkinson’s diagnosis appeared to triple risk of the disease, while use of primidone boosted the risk nine-fold. Meanwhile, the use of carvedilol and metoprolol was linked to a slightly decreased risk of Parkinson’s.
However, when researchers adjusted the data for the presence or absence of tremors, or for the use of these medications 18 months before Parkinson’s diagnosis, or when the analysis was restricted to patients with tremors, propranolol and primidone were shown to have minimal effect.
“Our results suggest that the onset of tremor in … [Parkinson’s pre-diagnostic] period may lead to propranolol use, and thereby a positive association with PD [Parkinson’s disease],” researchers wrote.
The fact that propanol and primidone – which do not suppress the beta-2 receptor – showed similar trends before and after adjustments further supports the non-association of medications that block beta-2 receptors with the risk of Parkinson’s.
The team also believes the results for carvedilol and metoprolol may be explained by their infrequent use by U.S. physicians to treat tremors.
Similarly, while salbutamol and inhaled corticosteroids were long thought to reduce the risk of Parkinson’s, the adjustment for smoking attenuated these associations, especially for salbutamol, for which the risk became close to null.
These findings highlight that, despite previous suggestions, medications that target beta-2 receptors do

Source: Parkinson's News Today