Whh would a 24f, previously intellectually gifted individual slowly begin to lose their memory? symptoms include aphasia, deja vu, inability to retain short-term memory, temporary amnesia, gaps in time, inability to understand speech, stuttering?

The main question for symptoms like these is whether the problem is neurological or psychological. It would be reasonable to first see a neurologist for careful evaluation. Good luck.

Alteration of cognitive function can be secondary to numerous problems: depression, anxiety, sleep deficiency, thyroid problems, vitamin deficiencies, chronic infections, prescription medication or recreational drug adverse effects, and numerous others. Start with your primary care physician, get evaluated, and discuss possible referrals to neurology or psychiatry.