You probably already know who comes to mind. The relative who makes every family gathering an ordeal. The colleague who generates drama whatever the situation. The friend who leaves you feeling worse than before you met. Most of us have at least one person in our lives who fits this description - and most of us have quietly wondered what all that friction is actually doing to us. New research published in one of the world's leading scientific journals suggests the answer may be more significant than we'd like to think.
What the science found
A study published in February 2026 examined how "negative social ties" - people in your close network who regularly create problems or make life more difficult - are associated with accelerated biological ageing. The researchers gave these people a name: hasslers.
The team analysed data from 2,345 adults drawn from the Person-to-Person Health Interview Study, a representative sample of the population of Indiana in the United States. Participants were asked to identify people in their regular social networks - and to name anyone who often caused them problems or made life harder. They also provided saliva samples, which the researchers used to measure biological ageing via two well-established epigenetic clocks: GrimAge2 and DunedinPACE. These tools measure chemical modifications to DNA that accumulate with age, and both have been linked to mortality risk in wider research.
The findings were clear. For each additional hassler a person regularly interacted with, their pace of biological ageing increased by approximately 1.5%. In practical terms, someone with at least one extra hassler in their life would age around 1.015 biological years for every calendar year that passes. Each additional hassler was also associated with a biological age roughly nine months older than their chronological age would predict.
Beyond ageing markers, participants with more hasslers in their networks showed higher levels of systemic inflammation, greater rates of depression and anxiety, higher body mass index, and more chronic conditions overall.
Why certain relationships are harder to escape
Not all difficult relationships affect the body equally - and this is where the study gets genuinely interesting. The strongest ageing associations were found for blood-relative hasslers: parents, siblings, adult children. The researchers suggest this is because family members are embedded in your life in ways that are much harder to renegotiate or exit. A difficult colleague, you can avoid. A difficult sibling at Christmas is another matter.
Perhaps the most counterintuitive finding is what the study revealed about ambivalent relationships - those that simultaneously provide genuine support and generate genuine stress. These mixed-signal relationships were associated with stronger ageing acceleration than relationships that were purely negative. The uncertainty, the obligation, the emotional effort of navigating someone who is sometimes wonderful and sometimes awful - that particular combination may place a heavier physiological burden than a relationship you've already mentally written off.
The study also identified who is most likely to report having hasslers. Women reported more than men. People in poorer health, daily smokers, and those with adverse childhood experiences were also more likely to have hasslers in their networks - suggesting that chronic social stress may compound other health vulnerabilities rather than operating in isolation.
A social dimension of health we often underestimate
In Britain, there is growing recognition that social health - the quality of our relationships, not just their presence - matters for physical wellbeing. The UK was the first country in the world to appoint a Minister for Loneliness, acknowledging that isolation is a genuine public health challenge. Research has consistently linked strong, supportive social connections to lower risks of cognitive decline, cardiovascular disease, and premature death.
This new study adds a different dimension to that picture. It isn't just loneliness that harms us - it's also the chronic stress of relationships we cannot leave, characterised by strain, conflict, or relentless difficulty.
What this study doesn't prove - and why that matters
The researchers are careful about what can and cannot be concluded from these findings. This is an observational study: it shows an association between hasslers and accelerated biological ageing, but it cannot prove that difficult people directly cause that ageing. People who are already ageing faster biologically may become more irritable, potentially generating more conflict in their relationships. Those with higher levels of negative affect may also be more likely to perceive neutral interactions as hassling. Confounding factors - health history, childhood experiences, personality - cannot be entirely ruled out.
What you can actually do
The researchers' practical advice is measured. Where you can, reduce regular contact with people who consistently drain rather than sustain you. Where you can't - because obligation, love, or circumstance keeps you in the relationship - limiting the time and emotional energy invested may help. The research doesn't say avoid everyone difficult - it says be thoughtful about your social environment as a whole. Strong, positive relationships are associated with real health benefits. The goal isn't fewer relationships; it's a better balance within the ones you have.
Therapy - either individually or within the relationship itself - was also suggested as a route for navigating difficult relationships that can't easily be exited. This may be particularly relevant for the ambivalent relationships that appear to carry the highest biological cost.