Aim of the study:
Borderline personality disorder (BPD) poses a significant challenge for modern psychiatry and clinical psychology due to its complex nature, high prevalence, and significant impact on the quality of life of patients. The study aimed to conduct a comprehensive analysis of current scientific data on the clinical picture, diagnostic methods, and therapeutic strategies for BPD to create a holistic view of this pathology and improve approaches to its treatment.

Subject or material and methods:
The methodology involved reviewing peer-reviewed articles, systematic reviews, and meta-analyses published in leading international medical journals, analysing diagnostic criteria from the DSM-5 and ICD-11, and assessing various psychotherapeutic and pharmacological interventions.

Results:
The results showed that the key symptoms of BPD – emotional instability, identity disorders, impulsivity, and instability of interpersonal relationships – form a complex interconnected system that determines the unique clinical profile of each patient. The high level of comorbidity of BPD with other mental disorders, especially depressive and anxiety disorders and post-traumatic stress disorder, has proven to be a key factor in determining the complexity of the clinical picture, prognosis, and treatment approaches.

Discussion:
The analysis of modern diagnostic approaches revealed a significant evolution from the categorical to the dimensional approach, which is most clearly reflected in the criteria of the International Classification of Diseases of the 11th revision (ICD-11). Structured diagnostic interviews demonstrate high reliability and validity, remaining the “gold standard” for the diagnosis of BPD in clinical trials.

Conclusions:
Self-report questionnaires showed good validity and reliability in screening and monitoring symptoms.