This paper examines two interrelated aspects of borderline personality disorder it s link to general intelligence and the effectiveness of Dialectical Behaviour Therapy for individuals with learning disabilities. Compared to control groups, individuals with BPD displayed significantly lower IQ scores. Additionally, distinct cognitive impairments were identified, potentially impacting emotional and behavioural regulation. Results showed that adapted therapy courses of DBT can have significant improvements in core DBT skills like emotional regulation, interpersonal effectiveness, and distress tolerance. Understanding the cognitive aspects of BPD can inform more effective interventions, while adaptable therapies like DBT can address the unique needs of individuals with learning disabilities. This dissertation encourages further exploration of the interplay between cognitive functioning and therapeutic outcomes, particularly in populations with personality disorders.