{"slug": "what-does-a-healthy-brain-look-like-turns-out-its-all-relative", "title": "What does a healthy brain look like? Turns out it’s all relative.", "summary": "A review study led by Northeastern University London researcher Haily Merritt concludes there is no universal neural signature of mental health or illness, because fMRI scans reflect how a person's social relationships have shaped brain activity. Merritt and colleagues examined studies pairing fMRI scans with information about people's relationships and found the imprint was especially pronounced in the default mode network, where past research linked both increased and decreased connectivity to depression depending on context. \"What is healthy depends on experience,\" Merritt said, and the authors argue the findings could reduce misdiagnoses and treatment trial and error by helping clinicians distinguish illness from learned coping.", "body_md": "# What does a healthy brain look like? It depends on the company you keep.\n\nA brain scan can’t tell the whole story. Northeastern researchers explore how our closest ties affect neural activity — and how understanding those bonds could change mental health care.\n\nSquishy, wrinkled, weighing about as much as a cantaloupe, the brain may not be much to look at from the outside. Yet with a network of roughly 86 billion neurons, it generates more impulses daily than all the smartphones on the planet combined.\n\nScientists can track all that activity with scans. But what does a well-balanced brain actually look like?\n\nSpoiler alert: new research says there’s no universal signature of mental health — or illness.\n\n“A lot of the work in neuroscience is trying to identify some kind of universal biomarker,” said Northeastern University London researcher Haily Merritt. To do this, scientists use techniques like functional magnetic resonance imaging (fMRI), which measure changes in blood oxygen levels.\n\nIn a [recent study](https://www.sciencedirect.com/science/article/pii/S0149763426003878?via%3Dihub), Merritt and her colleagues argue that scans look different depending on how a person’s social relationships have shaped their brain activity. Behaviors that let someone cope in one environment may prove unhelpful in another context, leaving unique neural traces that make the search for a universally “healthy brain” a perpetual wild goose chase.\n\n“What is healthy depends on experience,” Merritt explained.\n\nFor example, a certain pattern could reflect a useful adaptation in a person lacking strong supports, but might signal avoidance in someone with a solid crew.\n\nThe insights point clinicians to better treatment strategies and improved diagnosis by helping them distinguish illness from learned ways of coping while addressing the patient’s sources of distress in a way that prevents symptoms from returning. In the long term, this could mean fewer misdiagnoses and less trial and error in treatment. The findings also explain why the search for markers of mental health disorders kept producing conflicting answers.\n\n“This is a cornerstone of ‘treating the patient, not the problem,’” Michael Herman, a psychotherapist at [Tribeca Therapy](https://tribecatherapy.com/) in New York City, told Northeastern Global News.\n\nMerritt and her colleagues reviewed studies that paired fMRI scans with information about people’s relationships to examine neural connection patterns in different contexts.\n\nTo Merritt, the most profound insight was the fact that social bonds leave a visible mark on the brain at all.\n\n“Our social relationships are really important for how we engage with the world,” she said.\n\nThe imprint was especially pronounced in the area known as the default mode network (DMN).\n\nRegions in the DMN are involved in decoding other people’s emotions and managing one’s own feelings. The strength of the connections between them — and their links to other brain areas — varies with a person’s history and current social ties, Merritt explained.\n\nFor example, past studies connected an increase in communication between certain parts of the DMN with depression, while others linked the opposite pattern with the same condition, Merritt said. Factor in the social context that shaped brain activity, and the apparent contradictions start to make sense.\n\n“In one environment, more default mode connectivity is good. And in another, it’s actually harmful,” Merritt explained.\n\nPatterns of activity throughout the brain are linked to behaviors, which also make more sense in context. Understanding this can benefit clinicians who may otherwise be quick to count a behavior that’s serving a useful purpose as a sign of illness, Herman noted.\n\n“They might see someone guarded, hypervigilant, or committedly self-reliant, and see a problem that needs to be fixed,” he suggested.\n\nHowever, keeping people at bay may have offered protection after repeated betrayals.\n\nThe social context also explains why people with similar symptoms might need different guidance.\n\nOne patient might benefit from learning to set boundaries, while another could heal by letting people in, trauma expert and author of “[The Power of Attachment](https://traumasolutions.com/power-attachment-book/)” Diane Poole Heller suggested. \n\n“Encouraging more contact is only helpful when we understand the quality and safety of that contact,” she added.\n\nThe study mentions a feedback loop that forms when people with a history of reliable support become more receptive to help during difficult times. Each positive social encounter also builds the brain’s resilience to future stress. Those with weaker attachments, however, tend to back away, missing out on the much-needed assistance.\n\nHerman said this dynamic underscores why therapists should pay close attention to a patient’s past.\n\n“We can carry our earliest relationships inside us as blueprints for what to expect from other people,” he explained. Mental health struggles make it difficult to get past the assumption that reaching out won’t do any good — and the lack of close ties and strong social bonds makes recovery even harder.\n\nBut how exactly does the social environment turn into physical differences that show up on brain scans in the first place?\n\nOne possibility involves the stress response. Cortisol is a hormone released under stress, and simply holding someone’s hand in support can bring it down, Merritt explained.\n\n“When we feel supported … our stress responses calm and our sense of threat eases,” Herman said. “Even actual pain can feel less intense.”\n\nOver time, stress hormones change how readily brain regions communicate, altering patterns researchers measure on scans.\n\nOther emotional encounters leave their own imprint, according to Paul Hokemeyer, founder of the [Drayson Mews](https://draysonmews.com/), a London-based mental health advisory firm that provides consulting services.\n\nRepeated neural responses to positive and painful experiences form “an unconscious map” the brain uses to gauge whether new people can be trusted, he said.\n\nTo Merritt, the study’s findings are “a call to invest in our relationships and approach them mindfully,” she said.", "url": "https://wpnews.pro/news/what-does-a-healthy-brain-look-like-turns-out-its-all-relative", "canonical_source": "https://news.northeastern.edu/2026/10/20/social-bonds-brain-health/", "published_at": "2026-10-20 20:38:57+00:00", "updated_at": "2026-10-20 20:48:29.520778+00:00", "lang": "en", "topics": ["neural-networks", "ai-research"], "entities": ["Northeastern University London", "Haily Merritt", "Michael Herman", "Tribeca Therapy", "Northeastern Global News"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/what-does-a-healthy-brain-look-like-turns-out-its-all-relative", "markdown": "https://wpnews.pro/news/what-does-a-healthy-brain-look-like-turns-out-its-all-relative.md", "text": "https://wpnews.pro/news/what-does-a-healthy-brain-look-like-turns-out-its-all-relative.txt", "jsonld": "https://wpnews.pro/news/what-does-a-healthy-brain-look-like-turns-out-its-all-relative.jsonld"}}