Common ailment suffered by 80 million Americans increases suicide risk, study suggests
Seasonal allergies triggered by pollen appear to make deaths by suicide more likely, a new study has found.
US suicide rates rose 37 percent from 2000 to 2018; while structural causes are well-studied, short-term triggers are less understood.
To evaluate a possible link between seasonal allergies (which afflict inflict more than 80 million Americans) and suicide, a team of scientists from Wayne State University in Michigan and the University of Michigan combined daily pollen measurements with daily suicide counts across 34 US metropolitan areas from 2006 to 2018.
Because both pollen and suicide are sensitive to weather conditions, the researchers carefully accounted for temperature, rainfall and wind.
They also controlled for differences in local climate and plant life, since pollen levels vary by region, and for seasonal averages that might otherwise obscure results.
This allowed the researchers to compare suicide counts on days with unexpectedly high pollen to days with little or none in the same county.
The results, they said, were ‘striking’. Relative to days with no or low levels of pollen, they found that deaths by suicide rose by 5.5 percent when pollen levels are moderate and 7.4 percent when levels are high.
The increase was even larger among people with a known history of mental health conditions or treatment.
Seasonal allergies – triggered by pollen – appear to make deaths by suicide more likely, a new study has found (stock image)
They also showed that on high-pollen days, residents of affected areas experienced more depressive symptoms and feelings of exhaustion.
In terms of what is behind the link, the researchers say that it could be that ‘allergies exacerbate existing vulnerabilities, pushing some people toward crisis’.
They also suspect that sleep disruption is a the link between allergies and suicide rates.
More than 80 million Americans experience seasonal allergies each year.
Symptoms include sneezing, congestion, itchy eyes and scratchy throat. Most people experiencing these symptoms feel sluggish during the day and sleep poorly at night.
Allergy sufferers might not realize, however, that these symptoms reduce alertness and cognitive functioning; some of the factors that can worsen mental health and increase vulnerability to suicidal thoughts and behaviors.
Suicide rates have been growing steadily in the past two decades and, according to the CDC, more than 49,000 Americans died by suicide in 2022, and over 616,000 visited emergency departments for self-harm injuries.
Although socioeconomic and demographic factors are the most important predictors of suicide, much less is known about its short-term triggers.
The Wayne State University team say their study, published in the Journal of Health Economics, adds to growing evidence that the environment, including something as natural as pollen, can influence mental health risks.
This issue is likely to become more urgent as the climate changes.
They note: ‘Rising temperatures lengthen pollen seasons and increase pollen volume. Over the past two decades, pollen seasons have grown in both intensity and duration, and projections suggest they will continue to worsen.’
That means more people will experience stronger allergy symptoms, with ripple effects not only for physical health but also for sleep, mood and mental well-being.
Despite the scale of the problem, there are no national systems in the US to consistently measure and communicate pollen levels, the scientists reveal.
The CDC notes that suicide is one of the leading causes of death in the US
Suicide rates increased 37 percent between 2000 and 2018 and decreased 5 percent between 2018 and 2020. However, rates returned to their peak in 2022
They add: ‘Most communities lack reliable forecasts and alert systems that would allow vulnerable people to take precautions. This gap limits both prevention and research.’
Their study focused on metropolitan areas where pollen and death counts were available, but they cannot yet generalize their findings to rural areas.
That is a concern, they say, because rural communities often face greater shortages in mental health care and pharmacy access – and have seen rising suicide rates over the past decade.
For people who are already receiving mental health care, the researchers note highly that ‘recognizing and treating seasonal allergies is a key part of self-care’.
They advise investigating using over-the-counter medications, which can be highly effective to help reduce symptoms.
They conclude: ‘More broadly, people should be aware that during peak allergy season, reduced alertness, sleep disruptions and mood fluctuations may place an increased burden on their mental health, in addition to the allergy symptoms.
‘In terms of policy, improving pollen monitoring and public communication could help people anticipate high-risk days.
‘Such infrastructure would also support further research, particularly in rural areas where data is currently lacking.’
The research team’s next step, supported by the American Foundation for Suicide Prevention, is to examine the impact of pollen on rural communities.
This article was written by Shooshan Danagoulian, associate professor of economics at Wayne State University, for The Conversation.
