There may be no single cause of bipolar disorder (aka manic depression). Instead, research indicates the causes of bipolar disorder are probably a combination of biochemical, genetic and environmental factors that may trigger and perpetuate the chemical imbalances in the brain.
Net worth: $829 million. Telecommunications mogul Strive Masiyiwa is widely regarded as the richest man in Zimbabwe and is one of the richest men in Africa with a net worth of more than US$800 million.
This article refers to U.S. dollar billionaires who have Black African ancestry. According to Forbes 2014 ranking of the world's billionaires, Nigerian business magnate Aliko Dangote with a net worth of $25 billion is the world's richest black person.