@feruze-- Of course, an iron deficiency will impact memory and concentration. Any nutrient that's essential for cell function and interaction will do that and iron is one of them. Iron basically allows our cells and organs to breathe. Without enough iron, the number of red blood cells go down, which is called anemia. It's inevitable for someone with an untreated iron deficiency and anemia to be sick.
This is why your roommate experiences fainting and issues with concentration and memory. She needs to take her supplements as prescribed to avoid these symptoms.