The vegetable and fruit ingredients in a plant-based diet include many anti-oxidants which help fight disease and improve brain function. The top foods for brain health are vegan dark chocolate, blueberries, and black beans according to this article since they have the highest levels of anti-oxidants. It's nice to see black beans on the list since they are a wonderful ingredient - inexpensive and fit wonderfully into many recipes and meals including soups, stews, and salads. Plant-based foods such as these and others also maintain good heart health which improves blood flow to the brain prolonging its vitality.
Apart from eating well, the brain stays healthier over time with plenty of daily exercise per this research. Exercise was found to have more benefits than brain games in keeping the mind active and alert, even into advanced years. Memory, for instance, stayed intact with respondents who stayed physically fit.
Lastly, according to personal development expert Michael Gelb, optimism and creativity are linked. So the more optimistic one is, the more creative he or she will be which will lead to increased brain activity. Research has shown that vegan diets improve mood compared to meat-based diets. So, by correlation, more plant-based ingredients in one's diet will lead to better moods, more optimism, increased creativity and brain activity, and finally longevity of the mind!
So focus on eating well and exercising often and reap the benefit of a powerful mind and all the amazing things that flow from it!