Findings from a team of German researchers indicate that symptoms of borderline personality disorder and ADHD partially overlap, often appear together and can have unusually damaging consequences when they occur simultaneously. Borderline personality disorder (BPD) is an emotion-destabilizing mental illness that doctors typically only diagnose in adults. Attention-deficit hyperactivity disorder (ADHD) is a childhood condition that often continues to produce its effects in adulthood. In a study review published in 2014 in the journal Borderline Personality Disorder and Emotional Dysregulation, researchers from Germany\u2019s University of Freiburg sought to determine if BPD symptoms overlap with the symptoms of ADHD. They also sought to determine how often people diagnosed with borderline personality disorder have separately diagnosable cases of ADHD in adulthood. Borderline Personality Disorder Borderline personality disorder is one of 10 personality-based mental illnesses that doctors in the U.S. can diagnose under guidelines established by the American Psychiatric Association. Generally speaking, symptoms of the disorder center on loss of control over thought processes and emotional reactions, a seriously impaired ability to maintain positive social interactions and a seriously impaired ability to maintain control over reckless or impulsive moment-to-moment impulses. The nine specific potential symptoms of BPD include pronounced and often unreasonable fears of abandonment, lack of an enduring or cohesive self-image, rapid mood changes within a single day or over longer periods of time, repeated involvement in reckless or impulsive conduct, outbursts of anger that don\u2019t fit the social environment and repeated involvement in suicidal behavior or self-harming behavior not intended to cause death. The National Institute of Mental Health estimates that roughly 1.6 percent of American adults have borderline personality disorder; however, the actual percentage of affected individuals may be substantially higher. Statistically, women have higher chances of developing the condition than men. As with all other personality disorders, doctors usually only diagnose BPD after a person reaches his or her 18th birthday, even if symptoms of the condition manifest at an earlier age. This is true because teenagers and younger children naturally go through significant personality changes before reaching adulthood and therefore may only appear to have a personality disorder at any given point in time. ADHD Attention-deficit hyperactivity disorder is the shared name for three interlinked childhood conditions that involve unusually hyperactive or impulsive behavior, a lack of an age-appropriate ability to pay attention or a combination of hyperactive\/impulsive behavior and an inability to pay attention. In most cases, the disorder first appears in children under the age of 10. Figures compiled by the National Institute of Mental Health indicate that about 9 percent of all American teenagers have a diagnosable case of ADHD. Among adults age 18 and up, the ADHD rate stands at approximately 4 percent. Overlap of BPD and ADHD In the study review published in Borderline Personality Disorder and Emotional Dysregulation, the University of Freiburg researchers used a comprehensive review of studies previously published in the U.S. and Europe to identify common symptoms of borderline personality disorder and attention-deficit hyperactivity disorder to determine how often people diagnosed with BPD also have ADHD and to determine if people affected by both BPD and ADHD have substantially worse problems than people only affected by borderline personality disorder or attention-deficit hyperactivity disorder. After completing their review, the researchers concluded that borderline personality disorder and ADHD share two main symptoms: a lack of emotional stability and a tendency to act in impulsive or reckless ways. They also concluded that BPD and attention-deficit hyperactivity disorder appear together in the same individual in a substantial number of cases. One of the studies under consideration found a 14 percent rate of BPD in young adults affected by ADHD; this rate of BPD exposure far outstrips the rate found in the general adult population. In another study, the identified rate of borderline personality disorder in adults with ADHD was about 27 percent. The researchers also concluded that combined cases of BPD and ADHD have a significantly more negative impact on health and well-being than separate cases of either disorder. In addition, they concluded that the combination of borderline personality disorder and attention-deficit hyperactivity disorder is frequently much more difficult to treat. The most serious identified impact of combined BPD and ADHD is a sharp and damaging increase in the risks for behaving in unusually impulsive or reckless ways.