How to improve brain memory? are there any medicine for tht?

Not particularly: a good general diet especially with b vitamins would prevent brain damage. Avoiding concussions and alcohol. Mainly brain exercises for memory and mnemonics.

Some approaches: We have memory enhancing agents used for Alzheimer's disease, such as donepezil, memantine, and rivastigmine, but also prescription medical foods, such as Cerefolin-NAC, Axona, and phosphatidyl serine. OTC alpha-lipoic acid has been touted also, but not so clearcut in my experience. You and your doctor could discuss if your situation warrants such interventions.