I think a lot depends on what timescales you consider to be "speeded up". I don't think the perception that a huge amount of stuff happens between the ages of 16 and 18 and seems like it was only last week between the ages of 30 and 35 has much to do with cognitive decline. Feelings of WTF it's two hours later and I feel like I've only been editing for 10 minutes and just need 10 minutes more, likely are linked to cognitive decline, but I'm young enough to only have that feeling when I'm really, really tired, and I sometimes had it when I was 20 too...