Because of variability in risk factors and personality characteristics associated with suicide, subtyping can provide greater specificity and organization of findings than simple comparisons of suicidal to non-suicidal individuals. In this study, Q-factor analysis identified six personality subtypes of individuals with a suicide attempt history. As hypothesized, we identified subtypes reflecting the continuum of internalizing to externalizing personality styles found in many other classification systems for both Axis I symptoms and personality variables (Krueger and Tackett, 2006
). First, we found an Internalizing subtype (the largest group in our sample) that reflected chronically depressed, anhedonic, and passive personality features. Externalizers were well represented in the Psychopathic subtype, displaying substance abuse problems, criminality, imperviousness to consequences, and lack of remorse. In addition, difficulty with emotion regulation emerged central to one of the subtypes. The Emotionally Dysregulated subtype, seemingly a close relative of Borderline PD, mixes elements of internalizing spectrum symptoms with externalizing characteristics.
Three additional subtypes, albeit not entirely without precedence in past suicide research, described individuals who do not easily fit into the internalizing-externalizing distinction. First, the Dependent subtype contained individuals who fantasize about ideal love, often become attached too quickly, and fear rejection. Conversely, a Hostile-Isolated subtype contained social outsiders who lack relationships, are critical towards others, and are competitive. Finally, an Anxious-Somatizing subtype captures a hypochondriacal patient who uses their mental and medical problems to avoid responsibility. Unsurprisingly, they often catastrophize and develop somatic complaints when under stress. These last two subtypes shared the distinction of being more commonly associated with less likelihood of having a suicide attempt history.
Comparing current findings to past efforts at personality subtyping provides clues to how replicable these groups are. The Internalizing subtype embodies general negative affect present in many subtypes in previous studies (e.g., guilty neurotic, neurotic introverts; Engström et al., 1996
). Likewise, the Emotionally Dysregulated subtype has appeared most often in the form of Borderline PD symptoms (Ellis et al., 1996
; Engström et al., 1996
; Rudd et al., 2000
). The Dependent subtype also had clear counterparts in both Ellis et al. and Rudd et al. Additionally, the Psychopathic subtype overlaps with Ellis et al.’s Antisocial subtype, although our Psychopathic group appeared less impulsive and aggressive and more classically nonchalant and uncaring towards harming others.
Two subtypes matched less clearly with previous findings. Nevertheless, some of their characteristics are evident in past research. First, the Hostile-Isolated subtype had some overlap with Ellis et al.’s Schizoid group in their social isolation and angry/resentful attitude and with Rudd et al.’s Antisocial subtype in their competitiveness, criticality, and self-reliance. Further research may clarify distinctions, if any, among these groups. The Anxious-Somatizing subtype only shared similarities with the anxiety of the neurotic and introverted subtype (Engström et al., 1997
; Engström et al., 1996
). Somatization itself, though, has not been found in past subtyping efforts, possibly due to differences in measures or samples. Of the subtypes found previously, only one did not have a counterpart in the present study: the Histrionic-Narcissistic subtype (Ellis et al., 1996
). Overall, though, these subtypes show relatively strong convergence with past personality subtypes of suicidal adults.
Subtypes differed in meaningful and predictable ways on multiple measures not used in their derivation, including Axis I and II diagnoses, adaptive functioning, and childhood experiences. Furthermore, hierarchical regressions showed their dimensional form’s ability to predict adaptive functioning outperforms categorical Axis I and dimensional Axis II disorders, an impressive feature for these empirically derived personality subtypes. Thus, these subtypes gain the most utility when viewed as a set of dimensional prototypes to which any individual can match to varying degrees, resulting in an MMPI-like profile of elevations.
Limitations and Future Directions
This study has several methodological limitations. First, this study was cross-sectional of suicide attempters. Second, details about suicide attempts were quite limited in that no information about attempt frequency and time of the last attempt was available. Third, patients included in this study were in treatment and may not represent the entire population of suicide attempters. Nevertheless, because this sample has a wide variety of clinical settings represented, the sample should include most kinds of suicidal patients seen in treatment settings. Fourth, one informant provided all data. Ideally, patients would have been diagnosed by one observer and assessed using the SWAP-II by another. However, most published PD studies also rely on a single informant—the patient (e.g., via self-report questionnaires or responses to structured interview questions). The quantified observations of experienced psychiatrists and clinical psychologists (with an average of 17.7 years practice experience) are no less credible than self-descriptions of patients with personality pathology. SWAP data are also unrelated to theoretical orientation or other aspects of professional training (Betan et al., 2005
; Bradley et al., 2005
). If clinician biases exist, they appear to account for little variance in SWAP ratings. Finally, absence of psychosis and problems with personality were criteria for inclusion in the overarching study and may have affected the heterogeneity of the sample. The possibility of a psychotic subtype and/or a relatively healthy subtype exists. Future research in this area may illuminate the actual effects of these limitations.
This study of personality and suicidality has opened up several avenues of future research. One important area of future investigation is the exploration of additional, sex-specific subtypes, considering recent research has found different risk factors for suicidal acts in males and females (e.g., Oquendo et al., 2007
). Another possibility is that different personality subtypes exist in diverse ethnic groups. Although our sample had diverse ethnic representation, more diversity could lead to additional findings. Finding similarities and differences by sex and ethnicity will increase the much-needed specificity in identifying individuals at risk for suicide.
In sum, this study showed that personality subtypes of suicidal individuals do exist and are somewhat replicable of previous research. Subtypes differed on applicable variables and provided more predictive capabilities of adaptive functioning than DSM-based diagnoses. Two subtypes appeared especially related to suicide attempt history in clinical populations. Key clinical features for the Internalizing subtype included greater likelihood of being female, depressed, and avoidant whereas the Emotionally Dysregulated subtype was associated more with externalizing behaviors, less overall adaptive functioning, a traumatic childhood, and Borderline PD symptoms. Importantly, both subtypes were associated with a history of self-mutilation. Future research and experience will demonstrate the clinical utility in attending to personality subtypes in the assessment of suicidality, but if these findings are any indication, one may gain much over a simple list of one-size-fits-all risk factors.