If you’re over 40, working more than 25 hours a week could be affecting your intelligence, new research suggests. Editor’s Note (28 December 2016): Through the end of the year, BBC Capital is bringing back some of your favourite stories from 2016. Don’t do an IQ test after a full week’s work if you are 40 years or older. You could be disappointed. If you’re over 40, working more than 25 hours of w