I Have Been On Zoloft For At Least 12 Years

I have been on zoloft for at least 12 years and have found to still have problems. All that would happen was increase zoloft, but i always still had outburst and moodswings. I have found by dropping my zoloft from 100mg to 25mg has made me feel human again and have had no problems. I dont have mood swings any more. The question actually is, can decreasing the dosage cause memory loss as I am getting very forgetfull.