Polling proof exists that while memory impairment may show later, judgment can be impaired at 50, perhaps even mid-40's. The best judgment is among the young.

The young, who, unfortunately, need prodding to assure they vote.

This is in Minnesota, not nationwide, and go to the original Strib poll results page to see that those drinking well water, the further north one goes, have some premature and more severe judgment impairment.

__________UPDATE__________
One possibility, the young have hopes for the Democratic Party where getting to see the Clintons, the Podesta brothers, the DCCC and such, becoming jaded sets in. There was the spirit of Lyndon's Great Society, Hubert Humphrey's driving the Dixiecrats out of the Temple, all the things of days past, buried during the Clinton presidency, never mind philandering as a character fault. There is a need for resuscitation, and the push for Single Payer and taxation fairness and fair income/wealth distribution going forward being balanced by fossils alive and well. In the interim between the present faulted state, and Nirvana in the Democratic Party, there are the Republicans needing defeat. Voting regular citizens' best interest still is as it once was, only harder at times. Consider Amy and Tina, and the Republicans on the Judiciary Committee in reaching the decision about better if not best interests. There are Congressional seats that can be regarded as in play, in Minnesota, and they need to be played to the better side of Congressional potential. Even if dissatisfaction sets in, save the Boundary Waters since the threat there is existential. Whatever the young think or know of that Wilderness Area, the earth knows as well as it knows man-made global warming is a real thing. So, bottom line, vote. Vote not only your best interests, but the planet's.