What Personality Clusters Reveal About BPD and Why It Matters for Carers
Borderline Personality Disorder is a complex mental health condition, and no two people experience it in exactly the same way. A Swedish study of 141 people with BPD explored personality traits such as anxiety, impulsivity, aggression, emotional control, and social withdrawal to understand those differences more clearly. The researchers found that people with BPD could be grouped into three broad patterns, each with its own way of responding to stress, emotion, and relationships. For carers, this matters because it shows that BPD is not one single presentation. Understanding the person’s style of distress can make support more accurate, more compassionate, and far more effective.
Why researchers wanted to look beyond the diagnosis alone
A diagnosis of Borderline Personality Disorder tells us something important, but it does not tell us everything. Two people can both meet the criteria for BPD and still look very different in everyday life. One person may appear explosive, impulsive, and highly reactive. Another may seem quiet, withdrawn, anxious, and full of self-doubt. A third may appear more stable on the surface but still struggle internally in ways that need support.
The researchers wanted to understand these differences more deeply. Instead of focusing only on whether someone had BPD, they looked at personality traits that sit underneath the diagnosis. They used a questionnaire called the Swedish universities Scales of Personality to measure patterns such as anxiety, impulsiveness, aggression, emotional sensitivity, social withdrawal, and inhibition.
They also measured how severe the person’s BPD symptoms were, how well they could regulate emotions, and whether they had symptoms of anxiety or depression. This gave them a broader view of the individual, not just a label. What emerged was a more detailed map of BPD, one that may be much more useful for treatment and for carers trying to make sense of what they see at home.
BPD is one diagnosis, but it can be lived in very different ways. Looking at personality style helps reveal what kind of support a person may actually need.
The study found three broad personality clusters in BPD
The researchers identified three groups, or clusters, among the participants. These clusters did not mean there are only three types of people with BPD in the world, but they did show that certain patterns tend to group together.
The first cluster was described as the lower psychopathology group. These individuals still met criteria for BPD, but their overall difficulties were milder. They showed less aggression, less anxiety, less social withdrawal, and fewer problems with emotion regulation. Their personality profiles were closer to those seen in the general population, even though they still experienced real challenges.
The second cluster was called the externalizing group. These individuals showed more impulsivity and aggression. They were more likely to react outwardly when distressed. Their feelings often came out through action, anger, risk-taking, and difficulties staying calm.
The third cluster was called the internalizing group. These individuals were more withdrawn, more anxious, and more likely to turn distress inward. They avoided people more, had lower energy, and were more likely to be unemployed or on long-term sick leave. Their suffering was often quieter, but no less serious.
These three patterns help explain why BPD can look so different from person to person, and why the same advice or therapy style may not fit everyone equally well.
The lower psychopathology group still had BPD, but with less severe disturbance
The first group is especially important because it reminds us that not everyone with BPD presents in a dramatic or highly impaired way. People in this cluster still met diagnostic criteria, but their symptoms were less intense overall. They were less likely to be overwhelmed by anger, anxiety, or emotional instability, and their personality scores were closer to what might be expected in the wider population.
This does not mean they did not need help. It simply means their difficulties may be easier to miss or underestimate. A person in this group might appear to be coping reasonably well on the surface while still dealing with inner distress, fragile relationships, or identity struggles. They may not attract crisis intervention in the same way as someone in the externalizing group, but they can still benefit greatly from support, understanding, and treatment.
For carers, this matters because it challenges the idea that BPD always looks severe, chaotic, or visibly dramatic. Some people may live with BPD in a quieter form. They may still need structure, validation, and emotional support, even if their symptoms do not dominate every situation.
Some people with BPD appear more stable than others, but milder presentation does not mean there is no suffering or no need for support.
The externalizing group expressed distress outwardly
The second group was marked by impulsivity, aggression, and outward emotional expression. These individuals were more likely to act quickly when upset, say things they later regretted, or behave in ways that seemed reckless or intense. Their distress was externalized, meaning it moved outward into behaviour, conflict, or action.
This is the style many people most readily associate with BPD. When emotions rise, the reaction can be immediate and visible. Anger may flare quickly. Relationships may become stormy. Decisions may be made in the heat of the moment. For carers, this can be exhausting because the distress often enters the shared environment very directly.
At the same time, it is important not to interpret this pattern simply as bad behaviour or deliberate disruption. The study suggests that this group has real difficulty tolerating and regulating emotional arousal. What comes out as anger, impulsivity, or acting out may be a sign of emotion that is moving too fast and too forcefully to be contained internally.
This means support for this group often needs to focus strongly on helping the person slow down, identify emotions earlier, and find alternatives to immediate action when distress rises.
The internalizing group turned pain inward
The third group looked very different. Instead of expressing distress outwardly, these individuals tended to hold it inside. They were more anxious, more socially avoidant, and more likely to feel low in energy. They often found it hard to express themselves and may have appeared passive, withdrawn, or shut down rather than explosive.
This group is especially important because their suffering may be overlooked. A person who avoids conflict, stays quiet, and withdraws may not look as visibly distressed as someone who lashes out. But inward suffering can be just as severe, and sometimes more hidden. The study found that this group was more likely to be unemployed or on long-term sick leave, which suggests that their difficulties were deeply affecting daily functioning.
For carers, this cluster can be confusing because the person may not obviously ask for help, may struggle to explain what is wrong, and may seem resistant or distant when in fact they are overwhelmed. Their distress may show up as silence, retreat, exhaustion, and hopelessness rather than confrontation.
Understanding this pattern can prevent a common mistake. A withdrawn person with BPD is not necessarily coping better. They may simply be carrying pain inward rather than expressing it outwardly.
Not all BPD distress is loud. Some people suffer through withdrawal, anxiety, low energy, and emotional overcontrol rather than visible outbursts.
These groups were not just different in severity, but in style
One of the most valuable parts of the study is that it did not simply divide people into more severe and less severe illness. The clusters also reflected different styles of responding to stress. That is very useful because two people can both be unwell, but in different ways.
The internalizing group tended to be highly emotionally sensitive, but also inhibited. They often felt overwhelmed by sadness or anxiety, avoided conflict, and struggled to seek help directly. Their stress seemed to collapse inward.
The externalizing group also struggled with emotion, but their pattern was more reactive and immediate. Stress moved outward quickly into anger, impulsivity, or dramatic behaviour. Their distress often became visible to others very fast.
The lower psychopathology group still had BPD but showed more emotional stability overall, with fewer extreme traits on the personality measures. Their distress may have been more manageable, though still significant.
This distinction between severity and style is important. It reminds carers and clinicians that the key question is not only “how ill is this person?” but also “how does this person experience and express distress?”
Why this fits with newer ways of diagnosing personality disorder
The findings also support a newer approach to diagnosis, including the one used in ICD-11. Rather than relying only on rigid categories, this approach looks at both severity and personality traits. In other words, it asks not only whether someone has a personality disorder, but how severe it is and what kind of personality pattern is involved.
This can be very helpful in BPD because it moves away from one-size-fits-all thinking. A person with strong externalizing traits may need something different from a person whose difficulties are mainly internalizing and overcontrolled. Both may meet criteria for BPD, but their treatment needs are not identical.
For carers, this matters because it validates something many already know from experience: the diagnosis alone does not explain the whole person. The same label can cover very different realities, and support works best when it is tailored to the person’s actual pattern of emotion and behaviour.
A more modern view of BPD looks not only at diagnosis, but at severity and personality style. That gives a much more useful picture of what help may fit best.
Why treatment may need to differ between clusters
This study has important implications for treatment. Dialectical Behaviour Therapy, or DBT, is one of the best-known treatments for BPD and is especially helpful for people who struggle with impulsivity, emotional outbursts, self-harm, and unstable reactions under stress. That makes it a strong fit for many people in the externalizing group.
But DBT may not fit every style equally well. People in the internalizing group may be less impulsive outwardly and more emotionally overcontrolled. They may withdraw, avoid conflict, and struggle to express vulnerability. For these individuals, an approach such as Radically Open DBT, or RO DBT, may sometimes be more appropriate. This treatment focuses on overcontrol, emotional loneliness, and the difficulty of being open with others.
That does not mean each person neatly belongs in one therapy and not another. But it does suggest that treatment planning should consider whether the person’s pain tends to burst outward or collapse inward. Matching therapy to the person’s style of coping could improve outcomes and reduce the frustration that comes when a treatment seems only partly relevant.
What this means for carers in everyday life
For carers, one of the greatest benefits of this research is that it helps make behaviour more understandable. A loved one who is explosive, impulsive, and reactive may need a different kind of support from someone who becomes quiet, avoidant, and full of inward shame. The first may need calm containment, clear limits, and help slowing emotion before it turns into action. The second may need gentle encouragement, emotional safety, and support to express feelings they would normally hide.
This can also reduce confusion and resentment. Carers often wonder why advice that worked well for one person with BPD seems to fail completely with another. This study offers part of the answer. People with BPD do not all process distress in the same way, so the same intervention will not work equally well for everyone.
It also means carers may need to speak up when a loved one’s treatment does not seem to fit. If someone is highly internalizing and receives support focused only on managing outward impulsivity, important parts of their suffering may be missed. If someone is very externalizing and receives only quiet reflective support without enough practical emotion regulation tools, they may not get what they need either.
Understanding whether a loved one externalizes or internalizes distress can help carers respond more accurately and advocate more effectively for the right care.
Emotion regulation still sits at the heart of all three groups
Although the clusters differed, one thread ran through all of them: difficulties with emotion regulation. Whether a person acted out, shut down, or presented with milder symptoms overall, emotional difficulty remained central. That is why carers often feel they are dealing with emotional pain in one form or another, even when the surface behaviour changes.
This is an important reminder. The outward style may differ, but the core struggle is often the same. The person may be unable to understand, tolerate, or manage what they feel. In one person, that may lead to anger and impulsivity. In another, to anxiety, withdrawal, and inhibition. In a third, to quieter but still painful instability.
For carers, this means that support often needs to combine two things at once. One is responding to the person’s specific style. The other is remembering that underneath that style lies a common problem with managing emotion. That understanding can support greater compassion and more realistic expectations.
Conclusion
This Swedish study shows that Borderline Personality Disorder is not a single uniform condition. Among people with BPD, the researchers identified three broad patterns: a lower psychopathology group with milder symptoms, an externalizing group marked by impulsivity and aggression, and an internalizing group marked by anxiety, withdrawal, and emotional overcontrol.
These differences matter because they shape how distress is experienced, how it appears to others, and what kind of treatment may help most. For carers, the findings offer a more humane and useful way to understand a loved one. Instead of seeing only the diagnosis, they encourage us to see the person’s style of suffering.
That matters enormously. The more accurately we understand how someone’s BPD works for them, the better we can support them, advocate for appropriate care, and avoid applying the wrong assumptions. BPD is not one single pattern. It is a set of struggles that can look very different depending on the individual. Recognising those differences is one of the first steps toward better treatment, more compassionate care, and more hopeful outcomes.
Seeing the person behind the BPD label makes care more accurate, more compassionate, and more likely to fit what they truly need.
Source note
This article is based on Oladottir, K., Wolf-Arehult, M., Ramklint, M., and Isaksson, M. (2022), Cluster analysis of personality traits in psychiatric patients with borderline personality disorder, published in Borderline Personality Disorder and Emotion Dysregulation, 9(7).
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