I must say I found this research good news. German researchers compared 200 young workers (age 20-31) against older workers (65 -80 years old) for a period of 100 days. The researchers compared these two groups on mental skills such as how much they could learn, how their thinking skills varied from day-to-day and whether their memory functioned well.
The older group of workers did well; they were more consistent in their work and on a day-to-day basis they were highly motivated, and more stable in their moods. The older group used strategies they had learned earlier to solve new tasks. Interesting research. http://www.foxnews.com/health/2013/08/08/older-workers-have-fewer-senior-moments/