NEW DELHI: The company you keep may shape your life – and if it includes stressful or toxic people, it could even make you age faster.A new international study suggests that difficult or persistently stressful people in one’s social circle may quietly accelerate biological ageing and affect overall health.Researchers analysing social network data and biological samples from more than 2,600 adults found that individuals who reported having people in their lives who frequently caused stress or emotional strain showed signs of faster biological ageing. The findings have been published in peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS).The study described such individuals as “hasslers” – people who regularly create tension or emotional strain. Nearly three in 10 participants reported having at least one such person in their social network.Researchers measured biological ageing using saliva samples and DNA methylation patterns known as epigenetic clocks, which estimate how quickly the body is ageing at the cellular level.The analysis found that each additional stressful relationship was linked to about 1.5% faster biological ageing. On average, individuals reporting such ties were found to be roughly nine months biologically older than people of the same age who did not report them.A lead author of the study Byungkyu Lee advises being mindful about relationships, avoiding people who bring persistent negativity and stress, and distancing yourself if needed, though such decisions can be difficult. In many cases, however, completely cutting off “hassler” relationships may not be practical, especially when they involve family or ties that also bring some positive aspects.Dr V Mohan, chairman of Dr Mohan’s Diabetes Specialities Centre in Chennai, said persistent stress increases oxidative stress and free radicals in the body, which can shorten telomeres – protective caps at the ends of chromosomes – speeding up cellular ageing. Stress hormones such as cortisol, epinephrine and norepinephrine also remain elevated during prolonged stress, triggering inflammation, insulin resistance and damage to blood vessels, he said. Dr Rajesh Sagar, professor of psychiatry at AIIMS Delhi, said when stressful relationships repeatedly activate the brain’s fight-or-flight response, the body remains in a prolonged state of alertness. “This sustained stress response keeps cortisol levels high and can affect metabolic and cardiovascular systems over time, making the body biologically older than its chronological age,” he said.Participants with more stressful relationships also reported poorer physical health, higher anxiety and depression levels, and higher body mass index.Doctors said persistent emotional strain can manifest through headaches, digestive problems, sleep disturbance, fatigue and difficulty concentrating – signs that the body is struggling to cope with chronic stress.