Quit smoking could be leading to an increase in Parkinson’s
Previous research suggested smokers may have a reduced risk of Parkinson’s disease and anti-smoking campaigns from the late 40s could be behind increased prevalence of the disease decades later. People quitting smoking may be causing the rise in the number of Parkinson’s disease cases, a new study suggests.
But they are not advocating people should take up smoking as the risk of getting Parkinson’s are low and smoking causes a host of deadly illnesses.
The study published by JAMA Neurology of patients in a Minnesota county suggests the incidence of parkinsonism, which affected Muhammad Ali, and Parkinson’s disease may have increased over the past 30 years.
Dr Walter Rocca of the Mayo Clinic, Rochester in Minnesota studied trends for the disease in a county from 1976 to 2005.
Parkinsonism was defined as the presence of at least two cardinal signs: rest tremour, bradykinesia, rigidity and impaired postural reflexes.
Parkinson’s disease was defined as parkinsonism with all three of the following features: no other cause, no documentation of unresponsiveness to levodopa, and no prominent or early signs of more extensive nervous system involvement.
Read more: Third of people with Parkinson’s hide their symptoms due to ’embarrassment’
It included 906 patients with parkinsonism with a median age at onset of 74, of whom 501 were men.
Of the 464 patients with Parkinson’s disease with a median age of onset at 73, 275 were men.
Incidence rates of parkinsonism increased in men from 38.9 per 100,000 person-years between 1976 and 1985 to 55.9 between 1996 and 2005.
Rates of Parkinson’s disease increased in men from 18.2 between 1976 and 1985 to 30.4 between 1996 and 2005 and the increase was greater for men over 70 or older.
No similar overall trends were seen for women, according to the results.
Dr Rocca said the trends should be interpreted with caution for a variety of reasons, including that they may be due to increased awareness of symptoms, improved access to care of patients, and better recognition by doctors.
He said: “Our study suggests that the incidence of parkinsonism and Parkinson’s disease may have increased between 1976 and 2005, particularly in men 70 years old and older.
“These trends may be associated with the dramatic changes in smoking behaviour that took place in the second half of the 20th century or with other lifestyle or environmental changes.
“However, the trends could be spurious and need to be confirmed in other populations.”
Dr Honglei Chen f the National Institute of Environmental Health Sciences in an editorial added: “The epidemiologic observation that cigarette smoking is associated with lower Parkinson’s disease risk is robust but the debate over whether the association is causal seems never to be resolved.
“Given the substantial adverse health effects of cigarette smoking and low Parkinson’s disease incidence, it is almost impossible to directly examine this question in clinical studies.
“However, results of the study and a similar previous analysis may offer indirect support for causality: the increase of Parkinson’s disease incidence may follow decrease in cigarette smoking over the past 50 years, a trend that also affects men more than women.”