My close friend is suffering from memory loss. Are there any segulos in the Torah brought down to help improve memory and/or prevent forgetfulness?
There are number of things that are brought as segulos regarding memory and torah learning, (aside from various ways of learning in a way that one will retain his learning). Here are some of them. Eating olive oil, eating bread for breakfast, eating soft eggs without salt, dipping ones index and ring finger into salt and eating it.
The most important one though is to daven to H-shem that He should help improve the persons memory.
See Sefer Zikaron by Horav Chaim Kanievsky shli”a (Printed in Siach Hasadeh 1) where he bring numerous other things that help memory.