I don't think this complaint is suggestive of a 'neurological disorder'. It is common to forget what you read. Try to concentrate more. Get adequate sleep. Contrary to popular belief, you must sleep more whenever you study since it helps to consolidate your memory and helps you remember better. Physical exercise like brisk walking before studying also helps you remember better. You can accomplish a lot more in a couple of hours after a good night's sleep and a brief bout of exercise than staying for hours together awake in the night. Use your time wisely. Best wishes...