Sir,I Have Been Suffering Nightfall From 5 Years.Now I Am

Sir,I have been suffering nightfall from 5 years.Now I am 20 years old.Now a days I feel my intelligence and remembering is going to decrease cause of nightfall and I think I have happened anxiety and depression cause of nightfall. Sir, Is really decrease brain power cause of nightfall?If decrease brain power, then how can I improve my brain power? Hopping a response from your side. Thank you Sir.