Cluster analysis of normal personality traits in patients with psychogenic nonepileptic seizures.

The literature on patients with psychogenic nonepileptic seizures (PNES) suggests that they are a heterogeneous population. This study addresses this heterogeneity by describing subtypes of PNES based on a cluster analysis of normal personality traits in patients with PNES. In addition, the identified PNES subtypes are further described on dimensions of psychopathology as measured by the Minnesota Multiphasic Personality Inventory, Second Edition (MMPI-2), and cognition. Three personality clusters emerged: (1) very high neuroticism, low extraversion, low openness, high agreeableness, low conscientiousness; (2) average on all domains; (3) very high neuroticism, average extraversion, low openness, low agreeableness, average conscientiousness. Patients in clusters 1 and 3 appear to exhibit more severe psychopathology and a broader range of symptoms than those in cluster 2. Based on NEO-PI-R and MMPI-2 findings, tentative descriptions of the clusters are offered. Cluster 1 comprises "depressed neurotics"; cluster 2, "somatic defenders"; and cluster 3, "activated neurotics." Clusters 1 and 3 also differ significantly on neurocognitive testing, with cluster 1 significantly lower than cluster 3 in memory functioning, while cluster 2 individuals show generally average cognition across domains. These results suggest the existence of personality subtypes in patients with PNES that should be considered in the design of interventions for them.