Recent findings from a Canadian and American research group indicate that certain traits possibly linked to the onset of borderline personality disorder run within family bloodlines. Borderline personality disorder (BPD) is officially defined by the presence of at least five out of nine verified symptoms. However, people with the disorder may also share traits not included on the symptom list. In a study published in early 2015 in the American Psychological Association journal Personality Disorders: Theory, Research and Treatment, researchers from one Canadian institution and two U.S. institutions sought to determine if unofficial traits potentially associated with BPD are passed on through families. These researchers identified two such traits that may have a notable genetic component. Borderline Personality Disorder As with all other forms of diagnosable mental illness, the standard U.S. criteria for borderline personality disorder come from the American Psychiatric Association (APA). The APA recognizes nine symptoms of the condition: an extreme, realistic or unrealistic fear of being abandoned by others; recurring involvement in reckless behaviors that may endanger the self or others; an inability to maintain an accurate or stable sense of self; a recurring sense of apathy or emptiness; involvement in highly volatile personal relationships that veer from hatred to adoration; volatile changes in daily mood or outlook; a tendency to feel detached from reality or paranoid in stressful situations; repeated involvement in self-injuring behaviors that may or may not qualify as suicide attempts; and recurring bouts of anger that appear for no reason or are hard to control. Since a diagnosis of BPD requires just five of the nine acknowledged symptoms, the disease has a highly varied real-life impact on affected individuals. Unfortunately, suicidal behavior is one of the most common symptoms of the disorder. The National Institute of Mental Health (NIMH) estimates that up to four out of every five people with BPD engage in such behavior at some point in their lives. NIMH also estimates that up to 9 percent of all people with the disorder actually end up killing themselves. The best guess for the rate of borderline personality disorder in the U.S. (1.6 percent) is likely a significant underestimate, since the disease is often undetected or misdiagnosed as some other condition. Heredity and Mental Illness Current research indicates that some forms of mental illness have a substantial genetic component. The National Institute of Mental Health reports that five well-known illnesses\u2014major depression, bipolar disorder, autism spectrum disorder, schizophrenia and attention-deficit hyperactivity disorder (ADHD)\u2014appear to stem from a common, partially overlapping group of underlying genetic factors. In this context, it\u2019s worth noting that the symptoms of bipolar disorder and borderline personality disorder overlap to a considerable degree, and doctors must be cautious when trying to differentiate the two conditions. BPD Indicators in Family Bloodlines In the study published in Personality Disorders: Theory, Research and Treatment, researchers from Harvard Medical School, Harvard-affiliated McLean Hospital and Canada\u2019s University of Toronto Scarborough focused their attention on three traits that could potentially point to the presence of BPD but don\u2019t appear on the official symptom list: unusual aggressiveness, unusual anxiousness and loss of the ability to fully control conscious thought processes. The research sought to determine if these traits consistently appear in family members of individuals diagnosed with the disorder. A total of 1,161 people took part in the project, including two direct comparison groups of 126 individuals with a BPD diagnosis and 128 individuals without a BPD diagnosis, a third group of 93 adults diagnosed with major depression and 814 parents, brothers and sisters of the people in the two comparison groups or in the major depression group. The researchers concluded that aggressiveness, anxiousness and impaired control of conscious thought processes all appear to run in the family bloodlines of people with borderline personality disorder. However, the strength of these familial associations varies. For example, loss of control over conscious thought processes appears with some regularity in the families of people with BPD, while unusual aggressiveness appears only occasionally. The study\u2019s authors note that two of the traits under consideration\u2014unusual anxiousness and impaired regulation of conscious thought processes\u2014likely appear in people diagnosed with BPD often enough to qualify as additional symptoms of the disorder. In contrast, they believe that unusual aggressiveness does not appear in affected individuals often enough to qualify as a reliable symptom.