Bipolar disorder affects more people than you think.  Almost 1 out of every 100 adults has been diagnosed with this manic personality disorder.  One of my closest family members has been treated for a form of this mental illness that is associated with mood instability.  We all experience good and bad days but our highs and lows are usually not as extreme as a person with this illness.   They display all the common symptoms associated with it such as extreme ups (mania) and downs (depression). 

When I am around that person it feels like I'm riding a roller coaster.  I almost have to go along with the deep mood swings in order to avoid being the target of physical aggression.  One minute they are laughing uncontrollably, the next minute they are ranting about how they hate everyone.  Needless to say, it has definitely impacted my life because of the close relationship I have with this person.  

It also places a burden on coworkers or anyone else they come in contact with.  I would also observe their behavior and interaction with a significant other.  I noticed a consistency in the time they spent together was either really good or really bad, there was no happy medium.  They were either holding hands and looking lovingly into each other's eyes or getting into violent boxing matches. 

Most people with this disorder can function normally in society if treated effectively.  If you ignore it, it may lead to more severe and disabling tendencies or even suicide. 

1% of the population has been diagnosed with bipolar disorder, however many cases go undetected or get mistreated as depression.  My family member displayed some of the classic symptoms associated with the manic side such as inflated self esteem, euphoria, extreme optimism, tendency to be easily distracted, aggressive behavior, agitation, and spending sprees to name a few.  Some symptoms linked to the depressive side are fatigue, sadness, hopelessness, sleep problems, anxiety, irritability, and hopelessness.  Some people even suffer psychotic episodes, hallucinations, and delusions. 

This disorder has been linked to schizophrenia but the causes have yet to be determined.  There are three factors experts are researching- biochemical, genes, and environmental factors.  If you are a manic depressive you were probably born with the possibility of developing it but something that happened to you set it off.  It could have been a traumatic event like the death of a loved one, the loss of a job, or even relocating. 

People with self esteem issues have been known to develop bipolar symptoms.  There are also physical changes in the brain that affects chemicals called neurotransmitters which are tied to mood.  Hormonal imbalances may also be the culprit.  There has been a link between family members with mental illnesses, but studies have shown that one identical twin could have it and the other doesn't necessarily have to.