My mother complains about bad memory, fatigue, irritability, "brain shivers". and her mood is generally bad. she refuses to take her escitalopram because she says it makes her tired and gain weight.

Problem: Sounds as if you mother needs to see a psychiatrist or clinical psychologist and get her head in gear. Getting upset over this will not help. You have to express loving concern and support and perhaps have her respond simply to ease your anguish. She is probably frightened by some of this and needs reassurance. Be supportive. Good luck.

Needs new meds: Have her doctor reevaluate and prescribe new medications based on the diagnostic findings.