A number of common attributes are likely to be present in an individual suspected of having Borderline Personality Disorder. These signs can be observed as functional behaviors, but by themselves cannot diagnose BPD in an individual.

1. Extreme Mood Swings – People with BPD may experience dramatic mood swings from being very happy and in control of their world, to suddenly feeling very depressed, lonely, helpless, and hopeless. In similar fashion, people with BPD can move from a state of total independence to one demanding lots of attention.
2. Mirroring Others – People with BPD are quite intuitive and have the ability to read others very well. In the presence of others, the person with BPD is able to fit in much like a chameleon by assuming a similar position and mirroring similar feelings and behaviors. Self-image is based on the people around them. This allows the person with BPD to feel in control and liked by those present. The person with BPD tends to go in whatever direction the wind is blowing. There appears to be no depth of identity or individuality to their own thinking.
3. Addictive Behaviors – All people with BPD have some form of addictive behaviors, which can include eating disorders, excessive spending for unneeded items, sexual compulsions, and drug and/or alcohol abuse. People with BPD see themselves as in control of these behaviors, which provides a (false) sense of security.
4. Performance Failures – Many individuals with BPD have great difficulty consistently performing in educational and work settings because of their inability to stay focused in completing tasks. Thought disorders; difficulties in short and long-term memory; along with retention and retrieval of information problems may prevent people with BPD from reaching their full intellectual capacity.
5. Self-destructive Behaviors – People with BPD often have self-destructive behaviors that may threaten their life or physical well-being. It’s estimated that as many as 9% of all people with BPD commit suicide. Other self-injurious behaviors include self-mutilation (cutting), eating disorders, sexual promiscuity, and potentially life-threatening activities, such as excessive drug and/or alcohol usage, and reckless driving (road rage) without regard to their own life or the lives of others.
6. Intense, Unstable Relationships – People with BPD find it difficult to maintain any kind of close interpersonal relationships. Quite often the person with BPD may quickly develop an intense, exciting relationship with someone. The new partner is “perfect,” intelligent, gorgeous, fun, caring, loving, etc. Then, when reality sets in and they feel out of control, the person with BPD may do a complete 180-degree reversal. The inability to make decisions or commitments is very frightening to a person with BPD. Relationships with a person with BPD often end as abruptly as they start.
7. Black and White Thinking – People with BPD see things as either black or white. There are no shades of gray. The person with BPD is unable to see another’s point of view and understand how they may see it differently. Instead, it is either good or bad, right or wrong, my way or the highway. Compromise, or the ability to see other options is not possible for most people with BPD.