Baycrest Hospital in Toronto, Canada is a leading research facility for Alzheimer's Disease and many other forms of dementia. Their research has led them to document a 'brain-healthy diet' that not only may protect from neurodegeneration, it may also 'reverse' damage already done due to dietary, and lifestyle factors, as well as brain trauma like concussions.
You can see the diet and read more here:
This is corroborated by information here:
A brain-healthy diet is also a heart-healthy diet.