I am a med student and during a lecture we were learning about the effect of different chemicals on the body, and mainly on the brain. A fellow student asked a question which made him go on a very long tangent, where he got heated and started talking about chemicals he wished were more restricted. He began rambling about aspartame and basically began linking it to our lecture on the brain and implied that aspartame over time damages the brain when it gets into your body, and consumption of aspartame over a long period of time will begin to slow you down and decrease cognitive abilities.
He noticed what he was saying and quickly brought the lesson back on topic, but this stuck with me.

It makes sense, aspartame is in diet coke. The rush of sugary drinks on the market years ago caused an obesity epidemic. People to counteract this drink diet soda packed with aspartame. Aspartame is more addictive and people keep drinking diet soda thinking it is healthy. Population is made dumber and slower over time.