Parkinson’s Less Likely After a Heart Attack, Danish Study Finds
People who have had a heart attack are at lower risk of developing Parkinson’s disease later in life relative to the general population, according to a nationwide study in Denmark.
“These findings indicate that the risk of Parkinson’s disease is at least not increased following a heart attack and should not be a worry for patients or a preventive focus for clinicians at follow-up,” Jens Sundbøll, MD, PhD, the study’s first author with the clinical epidemiology and cardiology departments at Aarhus University Hospital, in Denmark, said in a press release.
While the reasons behind this reduced risk remain unclear, the researchers suggest they may have something to do with many cardiovascular disease risk factors, such as smoking and high cholesterol, being linked to an overall lower Parkinson’s risk.
The study, “Risk of Parkinson Disease and Secondary Parkinsonism in Myocardial Infarction Survivors,” was published in the Journal of the American Heart Association.
Cardiovascular problems can affect blood flow and blood vessel health in the brain, potentially resulting in blood clot-caused strokes and vascular dementia, a type of dementia that results from a series of small, silent strokes.
In agreement, heart attack survivors are at a higher risk of these cerebrovascular complications — which can cause vascular parkinsonism, a condition characterized by Parkinson’s-like symptoms due to a small stroke in motor-related brain regions.
Notably, a heart attack and Parkinson’s disease share several risk factors, including age and male sex, while coffee consumption and being physical active are reported to lower the risk of both diseases.
“Conversely, several studies confirm that classic cardiovascular risk factors, such as smoking, [high cholesterol], increased blood pressure, and diabetes,” are associated with a lower risk of Parkinson’s, the researchers wrote.
Whether this inverse association extends to overt cardiovascular events, such as heart attack, however, is unclear.
Sundbøll and colleagues at Aarhus University Hospital examined health registries from the Danish National Health Service between 1995 and 2016 to analyze the frequency of Parkinson’s and parkinsonism among people with and without a history of heart attack.
While Parkinson’s is primarily a neurodegenerative disease, parkinsonism “has several underlying causes besides primary neurodegenerative processes, including a variety of vascular mechanisms,” the researchers wrote.
They identified 181,994 people with a first-time heart attack during that period and compared their data with 909,970 age-, sex-, and year of heart attack-matched people with no heart attack history, used as a general population control group.
Patients’ median age at heart attack diagnosis was 71, and 61.7% of them were men. With a maximum follow-up of 21 years, the median follow-up period was 4.1 years for heart attack survivors and 6.6. years for those in the control group.
The heart attack group had, as expected, a higher proportion of cardiovascular disorders and simultaneous health conditions (comorbidities) than the general population group. Heart attack survivors had also slightly lower income and educational levels, and a larger proportion of them were unemployed.
Results showed that, during follow-up, a slightly lower proportion of heart attack patients developed Parkinson’s (0.5% vs. 0.7%) and parkinsonism (0.05% vs. 0.08%) compared with the control group.
As such, heart attack survivors had a lower cumulative frequency of Parkinson’s over 21 years (0.86% vs. 1.25%), as well as of parkinsonism (0.09% vs. 0.14%).
After adjusting for multiple factors known to influence the risk of either heart attack or Parkinson’s, the researchers found that heart attack survivors had a 20% lower risk of Parkinson’s and a 28% reduced risk of parkinsonism relative to the general population group.
Parkinson’s risk remained generally unchanged across subgroup and sensitivity analyses, while parkinsonism analyses were limited due to small sample sizes.
These findings highlight that heart attack is associated with a slightly lower risk of Parkinson’s, which may reflect “an inverse association with cardiovascular risk factors, such as smoking and blood cholesterol,” the researchers wrote.
There was not enough information about smoking and cholesterol levels among participants, however, to clarify these potential links, the team noted.
Still, Sundbøll emphasized that smoking “is definitely not good for your health,” being associated with an increased risk of “the most common diseases including cancer, cardiovascular disease and pulmonary disease.”
In fact, “there are very few diseases in this world in which smoking decreases risk: Parkinson’s disease is one, and ulcerative colitis [an inflammatory bowel disease] is another,” Sundbøll added.
“Our study is the first to examine the [heart attack]–Parkinson disease association, and from a clinical perspective our findings do not suggest the need for increased attention to development of Parkinson disease among [heart attack] survivors,” the researchers wrote.
Given that this study’s population was overwhelmingly white, these findings may not be generalized to people from other racial or ethnic groups, Sundbøll noted.