Personality Development: Why Neuropsychologists Don’t Talk About It (And Why We Should)

Personality development is a topic I’ve been well-versed in for several years, and it is a domain of psychology that I am proud to consider an expertise. Yet, since beginning a career in neuropsychology, it gradually became less and less a part of my professional conversations. In 2020, however, a research team and I presented a case study at the International Neuropsychological Society’s Annual Meeting on the very topic of personality development. The case was a young adult who sought a neuropsychological evaluation due to considerable cognitive, emotional, and social distress. The young man was so fraught with anxiety and depression that, prior to seeking an evaluation, he had attempted to take his own life. Results of his evaluation revealed profound deficits in his visuospatial processing skills that has likely existed since he was born, as well as an extreme rigidity of social avoidance that had developed into a personality disorder. Impairments in visuospatial processing are highly correlated with social communication deficits, and social communication deficits are correlated with many personality disorders. The case study of this young man posited that his lifetime of social struggles may have been the result of his visuospatial impairments, and they resulted in a pervasively rigid avoidant personality; in other words, that a personality disorder could potentially be linked back all the way to his early neurodevelopment.

Given my zeal regarding personality development, I was passionate about this research hypothesis and its implications on how we might understand the long-term effects of neurodevelopmental disorders; and yet, I also knew it was a scandalous position to take in the field of neuropsychology. There is an unspoken dogma among many neurodevelopmental specialists that we shouldn’t speak about or look at personality disorders; and we certainly shouldn’t diagnose them. The research on personality development is considered a so-called “soft science” within the already “soft science” of psychology, and I have had countless neuropsychologists make clear to me that they wouldn’t touch personality disorders with a 10-foot-pole. However, the concept of linking personality development to brain development can’t be all that scandalous if this case study was accepted for presentation at a global conference of neuropsychology. Nevertheless, I have continued to find myself in an uphill struggle to bring the concept of personality, and especially a personality disorder, into conversations with other professionals with specialties in neurodevelopment. This leads me to three critical topics that require discourse in our field: what personality development is, why neuropsychologists don’t want to talk about it, and why we need to.  

Personality is a construct that has been elusive to definition for as long as psychologists have been attempting to define it, but the medically-accepted definition is “an enduring pattern of inner experience and behavior” per the DSM-5. Simplified, our personality is how we interact with ourselves and the environment around us. For the most part, the factors that make up an individual’s personality aren’t ranked as better or worse than each other, and are instead accepted as just “different.” In fact, it is the array of differences that make up each of our unique personalities that make personality development so difficult to empirically define. Some terms, such as introversion and extroversion, are easily recognized by almost everyone; extroverts lose energy from being alone and gain it from being around others, while introverts gain energy from being alone and lose it in social settings. Neither of these factors is considered inherently better or worse than the other, but they are instead just known to be two different ways of interacting with ourselves and our environment. Personality Development refers to the factors that influence how we become inclined towards certain styles of self-and-other interaction. These factors have a dynamic influence on our personalities over the course of our entire lives; thus, personality is rather fluid and can change as the factors that influence it change.

A personality becomes “pathological” or “disordered” when it loses this fluidity and becomes inflexible to change. Personality Disorders are characterized by inflexible and pervasive interactional patterns that markedly differ from social norms, and, most importantly, cause a person (and/or those around them) social or emotional distress. Many factors influence how and when someone’s personality becomes rigid, atypical, and distressing. Some of these disorders are highly correlated with trauma and abuse, which can have a lasting negative impact on the extent to which an individual feels safe enough to appropriately interact with their environment. More recent discussions of how personality disorders develop tie in biological risk factors (e.g., biological propensity for heightened emotionality). The biosocial model of personality disorders theorizes two critical components: (1) a psychobiological deviation that puts an individual at risk of perceiving/interacting with their environment in a non-normative/divergent manner, and (2) life experiences that solidify the non-normative interactional pattern to the point that it becomes pervasive and inflexible.

 So, why aren’t neuropsychologists talking about these significantly distressing disorders that afflict a significant portion of the population? In my conversations with fellow neuropsychologists, I’ve heard a variety of answers to this question. The demand for non-normative behavior to be inflexible and, specifically, pervasive, in order to be considered a personality disorder is one reason many neuropsychologists shy away from these clusters of diagnoses. For most neuropsychological assessments, a neuropsychologist interacts with a client for a few hours; at best, perhaps they may test over a duration 2- or 3-days. The argument is then given that not enough time is spent with a client to be able to definitively establish that a pattern is pervasive; thus, it should only be long-term therapy providers who diagnose these disorders, because they know the client long enough. I have a few counters to this argument. First, a well-done comprehensive psychological evaluation should always involve contact with as many people in the client’s life as necessary. Neuropsychologists frequently speak with family members, educators, tutors, therapists, etcetera to gain additional clinical data besides just test scores to develop a diagnostic impression. Done appropriately, speaking with individuals who have known the client for several years can absolutely provide appropriate clinical data about the emergence of inflexible personality patterns and a timeline to establish pervasiveness. In addition, I can also argue that there are several diagnoses neuropsychologists readily give that also require an established pervasiveness. On both ends of the gamut in neuropsychology, from Autism Spectrum Disorder in pediatrics to Alzheimer’s Disease and other major neurocognitive disorders in geriatrics, a neuropsychologist should be speaking with people in the client’s daily life to look for a pervasive history if impairment. If a neuropsychologist can establish a necessary history of pervasiveness to diagnose autism, I see no reason they cannot do the same for other pervasive presentations like personality disorders.

Another argument I’ve heard from neuropsychologists who shy away from personality disorders is that there is not sufficient science behind the disorders and/or the psychological assessment measures used to aid in their diagnoses. This is untrue. Personality disorders have been heavily researched, and the validity of personality assessments has been established through several studies and several meta-analyses of those studies. Choosing to be ignorant of this empirical data is not a sufficient reason to avoid a set of disorders that are well within any psychologist’s ethical scope of practice. While within the scope of practice, however, another reason many neuropsychologists avoid personality disorders is their sense that it is not within their scope of competence. This is an ethical and valid argument, as we should never be operating outside our scope of competence; that is, we should be well experienced in any subdomain of psychology we actively practice. My concern, however, is how often personality disorders are not within a neuropsychologist’s scope of competence. I entered the field of neuropsychology after spending two years training at a psychiatric hospital, where I encountered a fair share of personality disorders. Early in my training in neuropsychology, I remember one of my supervising neuropsychologists telling me how impressed she was that I was integrating personality assessment measures into my neuropsychological testing; “more of us need to be doing that,” she said. The dogma against personality disorders within the field of neuropsychology has led to it being all but erased from the education and training of new neuropsychologists. This is a great disservice not just to the budding clinicians but also the clients they will assess and treat. There are too many training programs in neuropsychology that are not just keeping students and trainees blind to personality development, but may actively be telling their students to ignore or avoid anything related to personality. This is a practice that needs to change, and it’s a practice that I’m actively changing in my own training program. 

There is finally the notion that personality disorders are “severe” diagnoses that are heavily stigmatized, and they shouldn’t be given lightly. I don’t disagree with this, but my retort is that psychologists should not be giving any diagnosis lightly. We know several disorders present similarly, which is why an ethical psychologist will carefully consider all differential diagnoses when developing a diagnostic impression. An incorrect diagnosis can have a major negative impact on a client, as they may receive unhelpful or, even worse, harmful treatments if they are being treated for a disorder that they do not have. Further, the fact that personality disorders carry substantial stigma in professional circles as well as the general population is not a reason to avoid diagnosing them, but it is a reason to ensure we combat false stigma with accurate data and science. As psychologists, we have an ethical role to advocate for all clinical presentations and remove the stigma attached to mental health care in general; personality disorders should not be an exception to this rule.

This brings me to my final topic: why neuropsychologists should be talking about personality disorders. The case study my team and I presented at the international conference theorized that the client may have developed a personality disorder due to early neurodevelopmental deficits. I am not the first researcher to posit this theory. Many studies have linked neurodevelopmental disorders to personality disorder development later in life, with disorders such as ADHD putting individuals at a heightened risk for personality disruption in adolescence and emerging adulthood. We know several neurodevelopmental disorders are linked to social impairment, and there is even a neurodevelopmental disorder specifically for social communication deficits. If we know that neurodivergent individuals have a biological risk factor for negative environmental interactions, we must be willing to consider the risk that these interactions may become pervasive, inflexible, non-normative, and distressing. We need to be exploring neurobiological risk factors for pathological personality development as researchers, and we need to consider the risk as clinicians. This is especially true for pediatric neuropsychologists, who have the greatest chance of catching a personality disorder early. Early intervention is consistently shown to have the most robust treatment effects across almost all mental illnesses; this is no less true for personality disorders. There is a misnomer that personality disorders can only be given to adults, but (aside from one disorder) our diagnostic manual doesn’t have this requirement. The only rule is that the pattern be pervasive and that it emerges in adolescence or early adulthood; if we see it in adolescence, we need to be calling it how we see it. There is also a misnomer that personality disorders are resistant to treatment; in fact, several evidence-based treatments exist for personality disorders that can drastically improve an individual’s quality of life. Again, however, the earlier it’s noticed, the more likely the client is to be responsive to treatment. As pediatric neuropsychologists, we shouldn’t be hiding from disrupted personality development; we should be actively looking for it, as we are on the frontline for potentially identifying it early enough to nip it in the bud. We can help ensure that clients with neurodevelopmental risk factors receive prevention/early intervention services. By doing so, we can improve not just the cognitive functioning, but the social, emotional, and personality development of each client we assess.

 I encourage my fellow neuropsychologists to engage in more conversations about personality development, personality disorders, and how we can incorporate these concepts into our competency as practitioners. The research is growing; let’s be on the cutting-edge as we continue to understand the relationship between the brain and the personality that makes each of us, and our clients, unique.