Generally from all I have read and experienced personally, a handful of carefully mild to moderate trips in a lifetime have very little chance of causing any kind of disorder, learning or otherwise.
Of course, only you know how much is too much for you, so if you are thinking of trying acid START SMALL with the smallest dose you can, and gradually work up to something that you enjoy.
For many people large doses and/or frequent trips still seem to have no long-term ill effect, but for others the psychological effects are life-changing (for good or ill). Plenty of trip reports on erowid and elsewhere.
FWIW, to my knowledge none of the common bad side effects of LSD include learning problems or memory loss (which seems more common with marijuana). Rather, like other psychedelics, heavy use can cause a long-term disconnect from or dissatisfaction with reality, and in extreme cases a fundamental change in personality.
In the simplest terms, it won't make you stupid, just weird (read some Timothy Leary for a good example).