This is a good question, and unfortunately we don’t know exactly why borderline personality disorder symptoms tend to reduce with age (for more information on this phenomenon, see “The Prognosis for Borderline Personality Disorder”). However, experts have speculated that there could be a few reasons why this happens:
Some experts have speculated that BPD symptoms decline because the symptoms naturally “burn out” or that people simply grow out of the symptoms as they mature. In particular, research has shown that the impulsivity symptoms of BPD are the most likely to decline over time (which is consistent with the observation that, in general, older people engage in less impulsive behavior).
Other experts think that BPD symptoms may decline because as you age, you learn how to better manage your symptoms. For some people, this learning may come as the result of intensive treatment, but for others this may be the result of the natural learning that comes from negotiating life’s challenges.
Avoidance of Intimate Relationships
Finally, experts have speculated that BPD symptoms decline because over time you may learn to avoid situations that trigger symptoms. For example, for many people with BPD, problems in interpersonal relationships trigger the most intense reactions and symptoms. As a result, people with BPD may start to avoid interpersonal relationships altogether in order to reduce their distress. Joel Paris, one of the world’s leading researchers on the course of BPD symptoms, refers to this as becoming “comfortably alone.”
Oldham JM. Guideline Watch for the Practice Guideline for the Treatment of Patients with Borderline Personality Disorder. American Psychiatric Association, 2005.
Paris J. “Implications of Long-Term Outcome Research for the Management of Patients with Borderline Personality Disorder.” Harvard Review of Psychiatry. 10(6):315-323, 2002.
Stevenson J, Meares R, Comerford A. “Diminished impulsivity in older patients with borderline personality disorder.” American Journal of Psychiatry. 160(1):165-166, 2003.