Moreover, individuals frequently present with co-occurring personality disorders from different clusters. Prevalence estimates for the different clusters suggest 5.7% for dis orders in Cluster A, 1.5% for disorders in Cluster B, 6.0% for disorders in Cluster C, and 9.1% for any personality disorder, indicating frequent co-occurrence of disorders from dif ferent clusters. Data from the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions suggest that approximately 15% of U.S. adults have at least one per sonality disorder.