Lumosity Performance Index, or LPI, formerly Brain Performance Index, or BPI, is the measure of how well you do on Lumosity.
It probably started in 2009 as BPI
The information of change in BPI was removed from daily training sessions in 21st December 2013.
The information of change in BPI was removed from training summaries in 22nd April 2014, due to the cause of harm to brain trainers instead of the cause of ability to focus.
In 28th June 2014, BPI was changed to LPI