Willis finds those who stay on the job after age 60 stay sharper than early retirees
"5 Reasons to Start a Business after You Retire" - MSN Money. 12/1/2015.
In their examination of the relationship between cognition and labor force status across the US, England, and Europe, Susann Rohwedder and Bob Willis found that early retirement appears to have a significant negative impact on cognitive ability among people in their early 60s. Thus, older people in countries like the US, which has a relatively high retirement age, had higher cognition scores than those in countries like Spain, where workers tend to retire earlier. Willis also found that retirees reported being slightly more bored than when they were working.