High testosterone correlates with aggression, and young people have way higher T than elderly. Should we ban people in the highest T quartile from becoming politicians? Of course not. It's a complex and highly individual problem which can't be solved by filtering via just one variable, like age, gender, level of brain deterioration, or some hormonal level.

Here are some problems that _don't_ prevent people of any age from becoming a congressman or woman:

- Alcohol abuse

- Narcissism and/or sociopathy

- High debt

- Cult membership

- Most importantly: Personal financial interest in specific policy changes

Why not start with these? Banning elderly because they on average tend to be more gullible seems like a weird way of addressing governmental issues.

On a different level, I find the idea of banning people from governmental positions based on a specific trait deeply undemocratic, and a slippery slope. Principiis obsta.