There are 10 recognized PDs divided into clusters A, B, and C. All 10 PDs have a combined prevalence of approximately 10% in the general population. They are associated with male sex, low socioeconomic class, and poor education, although there are different epidemiologic patterns for specific PDs. There is a very high rate of PD among patients presenting for psychiatric evaluation.
Cluster A disorders are typified by behaviors and thoughts that would be considered odd or eccentric; this cluster includes schizoid PD (detached and limited range of emotions), schizotypal PD (limited social attachments but also distorted thinking, such as magical thinking), and paranoid PD (distrustful). Such patients may present with medication noncompliance (paranoia regarding rationale for prescription) and approach their medical problems with metaphysical explanations.
Cluster B disorders are typified by excessive emotional and dramatic responses and include antisocial PD (lack of respect to rules or empathy toward others), borderline PD (impulsive behaviors along with unstable and erratic interpersonal relationships), histrionic PD (excessive emotional responses, especially in efforts to get attention), and narcissistic PD (lack of empathy to others and grandiosity). These patients might present to medical personnel after self-injurious behavior or present histories with exaggerated seriousness (eg, near-death experiences).
The Cluster C grouping includes avoidant PD (excessive shyness, poor self-image, hypersensitivity), dependent PD (passivity in decision-making and submissiveness), and obsessive-compulsive PD (a need for control and perfection). This cluster is driven by underlying anxieties. These patients may have extreme difficulty making medical decisions, often deferring to the provider or a significant other, may feel criticized by health suggestions such as losing weight, or may be inflexible to changing treatment directions in light of new data.
Patients with these disorders may have an increased risk of various general medical conditions.
F60.9 – Personality disorder, unspecified
33449004 – Personality disorder
Differential Diagnosis & Pitfalls
- Mental illness (broad differential depends on which PD but includes mood disorders, psychotic disorders, etc)
- Wilson disease
- Heavy metal toxicity or poisoning (see arsenic poisoning, lead poisoning, mercury poisoning, thallium poisoning)
- Substance use disorder (see alcohol use disorder, benzodiazepine use disorder, cannabis use disorder, cocaine use disorder, methamphetamine use disorder, opioid use disorder)
- Epilepsy (see seizure)