Chapman PF, White GL, Jones MW, Cooper- Blacketer D, Marshall VJ, Irizarry M, Younkin L, Good MA, Bliss TVP, Hyman BT, Younkin SG, Hsiao KK 1999 Impaired synaptic plasticity and learning in aged amyloid precursor protein transgenic mice. doxycycline photosensitivity A related problem is that the most common symptom in women, vaginal discharge, is usually due to non- sexually transmitted reproductive tract infections RTIs and is not a good indicator of STI.