New research shows that smoking in childhood harms the heart far earlier than previously thought. Even if young smokers have no visible health problems, their hearts pump blood less efficiently and grow abnormally. Scans reveal that, by their mid-twenties, young smokers’ hearts are already under strain – putting them on a fast track to serious health risks. The findings highlight the urgency of early intervention to prevent lifelong damage.
It is a cinematic trope – rascally teenagers share a pack of cigarettes in the boys’ bathroom. As long as they kick the habit before they become adults, it is a harmless youthful indiscretion, right?
But new evidence presented in the Journal of the American College of Cardiology demonstrates that smoking cigarettes during childhood rapidly affects the heart’s structure and function.
Even if young smokers do not show outward signs of poor health, their hearts pump blood less efficiently and grow larger than those of their nonsmoking peers – and this can set them on “jet speed toward disaster” if left unchecked, says author Andrew Agbaje, a physician and Professor of Clinical Epidemiology at the University of Eastern Finland in Kuopio.
“Certain injuries sustained from smoking might be reversible if we do something at the right time,” Andrew Agbaje says. But these new findings mean that intervention must come even earlier than previously realised. “We cannot afford to wait until our twenties to take smoking seriously.”
Scanning hundreds of young hearts
Previous research has focused on easier-to-measure markers of how smoking might impair an adolescent’s circulatory system – such as changes to blood vessels or blood oxygenation.
But a long-term study of children in the United Kingdom provides a rare opportunity to peer directly into the hearts of kids who were, by all external metrics, healthy and developing normally.
The Avon Longitudinal Study of Parents and Children has tracked nearly 15,000 people born in the early 1990s since birth, gathering data on their growth through visits to the clinic and surveying both parents and children on their lifestyles.
Children in the Avon cohort completed questionnaires on their habits at several points throughout adolescence and were asked whether they had smoked cigarettes in the past 30 days at the ages of 10, 13, 15, 17 and 24 years.
What makes the Avon cohort unique is that echocardiography – using ultrasound waves to map the heart’s structure – was performed on nearly 2,000 of the participants at age 24 years. And just under 900 of these had an additional echocardiogram at age 17 years, enabling researchers to compare the heart’s development with an interval of seven years.
“Performing echocardiography in the hearts of thousands of people takes a lot of money – especially when they are not sick,” Andrew Agbaje says.
When it is dangerous to have a big heart
The behavioural data alone tell a compelling story, Andrew Agbaje says. “The rate at which the adolescents took up smoking was remarkable,” he says. Only 0.3% of the children reported smoking at age 10 years, but that jumped to 14% by age 15 years. By age 17 years, about one fourth of the participants reported smoking.
Regardless of when they started, about 60% of the participants who reported smoking were still smoking at 24 years.
The echocardiograms revealed striking differences between the hearts of children who smoked and those who did not, Andrew Agbaje says. Smokers had a thicker muscular wall in the heart’s left ventricle – a symptom associated with an elevated risk of heart attack in the long term. But in the short term, is this just a structural change, or does it affect the heart’s function?
Comparing the two echocardiograms provided the answer. “As they grew from 17 to 24 years old, the hearts of smokers enlarged more rapidly than the hearts of nonsmokers,” Andrew Agbaje says.
This is clear evidence of a heart struggling to meet the body’s needs, he explains. If the heart is not pumping blood properly, it often grows to try to compensate. “When a child’s heart gets enlarged, that heart needs more oxygen to be sustained,” Andrew Agbaje says. “The heart begins to pump faster to get more blood supply, so the heart rate rises. Not only that, but because the blood flows faster, the blood pressure will rise.”
“It becomes a vicious cycle that results in continual enlargement of the heart, more rapid heartbeat, and so on,” Andrew Agbaje says.
Without intervention, this cardiac stress can lead to heart failure and cascading damage to the kidney, lungs and other organ systems. “Young smokers are on a jet speed to disaster,” he adds.
No free tickets for children
“A concept has been sold to us – that smoking really does not affect us until we are adults,” Andrew Agbaje says. “This is almost a free ticket to keep us smoking, thinking that by the time we get to adulthood, we will just throw away the tobacco before it harms us.”
But the Avon cohort demonstrates that smoking’s damage to the heart is already visible in adolescence. These results should be a flashing warning sign for policy-makers around the world, Andrew Agbaje says. Data from 27 countries in the European Union indicate that about 15% of people 15–24 years old smoked tobacco products daily in 2019. “We cannot discard what we are seeing,” he says. “We just have to be bold and speak truth to power: the tobacco industry and government legislators.”
These findings mean that intervening early as children begin experimenting with cigarettes is even more crucial. “Growth throughout life builds on what has happened in the past – almost like an autopilot situation,” Andrew Agbaje says. “The trajectory you begin with, you are likely to continue with. And for the heart, a minor risk develops into a major risk.”
Studies of adults show that the heart takes time to return to a healthy state. “When adults stop smoking tobacco, it reduces their risk of heart failure,” Andrew Agbaje says. “But because they have been smoking for a while, that smoking problem remains in their system, and the risk of heart failure persists for the next 30 years.”
“We need to move back the threshold. Let us stop smoking at age 17 years, not 37 years,” he adds. “The ability for the heart to restore to normal begins to depreciate as we grow older.”
