I have no idea how to do this or if it is possible but I have a main table of information (participant ID, years or visit and score for each visit).

participant Start date Stop date
1 22/10/2008 05/03/2013
2 01/01/2008 13/02/2008
3 01/01/2010 01.01.2016
4 20/05/2009 31/12/2009
5 01/07/2011
6 15/01/2005 18/07/2005



Then I have an additional table of information. Each participant started a drug at some point during testing (but they started it at different times)


participant 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
1 123 125 118 41 74
2 236 236 222 239 262



Ultimately I would like one table which shows score before and after starting the drug for each participant. Is there anyway to do this? (There may be a few 'before' or after' scores)

Participant Before After
1
2
3