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$800 million.
Being a millionaire (in Zimbabwean bond coins, abolished since 2009) in Zimbabwe is considered extremely poor. At the end of 2015, there were just over 13 million US$ millionaires or High-net-worth individual (HNWIs) in the world.