I disagree with every member here who suggests 'age does not matter'.
'It depends'.... The mind is not quite as sharp as you get older. This shouldn't restrict you in micro/low level buyin stuff... or low buyin Live games either, but as you move up & begin battling vs. good players I believe it can make a substantial difference.
There aren't many older players these days on the tops of leaderboards or crushing the Hi-Rollers.. Live or online. One of the oldest I've seen with good results online is 'raidalot' (Talal Shakerchi). Talal would be considered 'old' compared to most, at the not very old age of '55'.
Also, prior to his SCOOP $10k MainEvent win (~$1.5 million), online he was actually a losing player, with an ROI of ~ -20 to -30% for a net of approx. -$400,000.