Difficulties are frequently encountered in distinguishing between Bipolar Disorder and Borderline Personality Disorder, with differential diagnosis being complicated by the presence of comorbidity. The present study aims to evaluate the utility of the Millon Clinical Multiaxial Inventory-III (MCMI-III) in discriminating patients affected by “pure” Bipolar Disorder from those affected by Bipolar Disorder with Borderline Personality or Other Personality Disorder.
57 patients (M = 20, F = 37; mean age 47.9 ± 10.8 yrs) affected by BD (BD-I 51%; BD-II 49%) in clinically stable remission were recruited; 28 patients were affected by BD (49.1%), 18 by BD and BPD (31.6%), 11 by BD plus Other Personality Disorders (OPD) (19.3%). Subjects were submitted to SCID-I and SCID-II and rated by the CGI-severity and GAF scales, and MCMI-IIII.
MCMI-III scales focusing on “clinical syndromes” and “severe clinical syndromes” revealed significantly higher mean scores for comorbid patients on all scales, with the exception of somatization and posttraumatic stress scales. In particular, BD + BPD scored highest on Anxiety, Bipolar-manic, Alcohol dependence, Drug dependence and Thought Disorder scales, while BD + OPD scored highest only on the Dysthymia scale. With regard to “clinical personality patterns”, highly significant increases in mean scores were obtained for depressive, narcissistic, antisocial, sadistic-aggressive, passive-aggressive scales among BD + BPD patients, who conversely displayed the lowest scores on the obsessive-compulsive scale. Moreover, the highest scores on Avoidant, Dependent and Self-Defeating Scales were obtained by BD + OPD patients, who likewise scored lowest on the Histrionic Scales; no difference in mean scores was detected for the Schizoid scale between BD, BD + BPD, and BD + OPD patients. On taking into account “severe pathology scales”, the highest mean scores for the Borderline scale were detected among BD + BPD, and among BD + OPD for Schizotypal Scale; no inter-group differences emerged with regard to the Paranoid scale. Cluster B and C scales discriminated respectively between BD + BPD and BD + OPD patients (Table II).
MCMI-III may prove to be useful in identifying Bipolar patients with comorbid BPD in routine clinical practice