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.
Dangote. Listed two years consecutively as Nigeria's richest man, his net worth in 2005 was $1.6 billion, and $4billion in 2006, now he's valued at $8billion in 2007.