How Inflammation and Stress Affect Emotion Regulation in Borderline Personality Disorder

For many families navigating life with a loved one diagnosed with Borderline Personality Disorder (BPD), the journey can feel overwhelming. From intense emotional swings to self-harm risks, carers are often left wondering: why is it so hard to help someone you love, and what’s really going on beneath the surface?

A recent review in Neuroscience & Biobehavioral Reviews offers a promising new perspective—one that places the biological processes of inflammation, anxiety, and stress at the centre of how disorders like BPD function. While these insights don’t offer a “cure,” they do shed light on why emotional dysregulation happens and how we might better support recovery.

What the Science Tells Us

Borderline Personality Disorder (BPD) and Bipolar Disorder (BD) share a striking number of features: emotional instability, impulsivity, and intense anxiety, among others. But beyond the behaviours, researchers have begun to uncover shared biological signatures—particularly around how the body handles stress and inflammation.

Both disorders appear to be linked with altered immune function. Inflammation—normally the body’s way of fighting off infection—seems to misfire, contributing instead to mood swings, anxiety, and cognitive symptoms. The review outlines how stress, especially in early life, primes the body for this overreaction. And in those with BPD or BD, the stress response system (notably the hypothalamic-pituitary-adrenal axis) doesn’t just overreact; it becomes chronically dysregulated.

The findings are especially relevant for carers because they validate something many already feel: that their loved one’s reactions aren’t just psychological—they’re biological too. Emotional outbursts or shutdowns aren’t simply about “being difficult” or “attention seeking”—they may reflect a body stuck in survival mode.

Why Inflammation Matters

Inflammation is measured through markers like cytokines (small proteins involved in cell signaling). These markers spike not only during infections but also in response to psychological stress and anxiety. People with BPD show elevated levels of certain inflammatory molecules—especially after stressful events.

The implications are big. If inflammation worsens emotional regulation, then repeated stress at home (arguments, crisis moments, feeling helpless) may create a feedback loop that maintains or even worsens symptoms.

Understanding this helps shift the narrative. BPD is not just a disorder of thoughts or relationships—it is also rooted in how the body responds to life’s pressures. And while this doesn’t excuse harmful behaviours, it does offer a new route for empathy, and potentially, for intervention.

The Stress-Anxiety Loop

Carers frequently witness their loved one swinging between emotional extremes, often triggered by what appear to be minor stressors. This may be because of how closely stress and anxiety are tied in BPD. The study describes how these two forces interact with inflammation in a “vicious circle,” amplifying each other over time.

More worryingly, the stress system in people with BPD appears “blunted”—producing less cortisol (a key stress hormone) in response to threats. This may sound like a good thing, but in reality it means the body isn’t regulating stress effectively. Instead of calming down after a difficult moment, the person remains in a heightened state, leading to explosive or withdrawn reactions.

What Does This Mean for Carers?

These findings can feel daunting, but they also point to new strategies for carers:

• Create Low-Stress Environments: Reducing the number of triggering events can interrupt the cycle of stress, inflammation, and dysregulation. BPD UK’s resources—like our AI Coach and webinars—can help carers learn how to de-escalate situations and respond constructively.
• Prioritise Emotional Safety: While you can’t eliminate all conflict, consistent, non-reactive support helps calm the stress system over time. Think of it as giving the body space to heal.
• Recognise the Invisible: When your loved one seems “over the top” or withdrawn, remember—this may reflect immune and stress system changes, not just mood. This perspective can protect your own mental health by reducing personal blame or frustration.
• Take Care of Yourself: Chronic exposure to stress and crisis affects carers too. You are at risk of anxiety, sleep disruption, and even your own immune changes. BPD UK’s support groups and self-paced courses are designed to help you cope and stay well.

What Comes Next?

There is still much we don’t know about how exactly inflammation, stress, and anxiety interact in BPD. However, this research reinforces a growing consensus: effective care for BPD must address both mind and body—and carers are key to making that possible.

At BPD UK, we believe that supporting carers with evidence-informed tools and compassionate guidance is not just helpful—it’s essential. When you understand the science, you’re better equipped to support your loved one and protect your own health along the way.

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If you’d like to read the full scientific article, you can find it here. For more practical advice and peer-led support, explore our webinars, support groups, and the BPD Coach on our website.