If there is any age restrictions that could be placed on positions of power, it should be on younger people. Younger people tend to be unrealistic, idealistic and do not have a balanced objective view of society. This stems from the large number of younger people that are not fully contributing members of society yet, some have never had a job, many responsibilities, or have never paid taxes.
Furthermore the brains of young people actually function differently. The prefrontal cortex of the human brain, the area associated with executive decision making, does not fully develop until the age of 25 years old in the average adult. This executive decision making process includes determining good and bad, better and best, same and different, future consequences of current actions, prediction of outcomes, and expectation based on actions. All of which are attributes that help an individual make an informed decision. It would therefore be beneficial to limit the age of positions of power to those potential candidates who's brain has reached full maturity, when it is scientifically proven to be able to process the nuances of complicated political, social, and legal matters.