BDNF - Brain derived neurotrophic factor
Strengthens synapses and increases neuroplasticity
The best way is to do intense exercise, high skill sports with constant on and off activity.
Do this as often as you can as your trying to increase baseline bdnf, atleast 4 times a week of a hour of very intense exercise
Eat fatty fish 3 times a week, salmon or sardines, if you can afford it buy wild caught fish.
Be consistent and after a few months your mental performance will improve significantly