You will find lots of other factors that correlate with that curve over the last 100 years. Life expectancy, consumption of processed foods, exposure to many many other chemicals etc. etc.
Also, Aluminium is not a heavy metal.
Discussion
Yes I am aware of that. Some other correlating factors may have contributed to it too, while other may have nothing to do with it. There are studies though showing aluminium in brains of alzhaimer, multiple sclerosis and autism patients is elevated, which shouldn't be ignored.