Hi, Thanks for writing in to us. There are many conditions which can make you feel mentally weak and have symptoms like inability to memorize. It is suggested that you get investigated for any medical condition which might be causing your problems. You can get thyroid function test done to know if your thyroid functions are normal. If your thyroid function is abnormal then it can cause these symptoms and treatment is usually with medicine to control the thyroid hormone level. Please get a blood count done to know if you are having anemia and also get your iron and vitamin B12 levels. Anemia can cause weakness and tiredness and this is the case with many people. Correction of hemoglobin level and iron supplement helps. Vitamin B12 supplements might be required. Hair whitening is in the genes and some times it can happen due to malnutrition and vitamin E deficiency. Please have a balanced diet and make your life style healthy. Anxiety and stress can cause the symptoms like difficulty in memory and weakness. Please control your stress level and do physical exercises to keep your mind free from anxiety. Please do not worry