hello user, i got through your problem and understood that your mother is suffering from depression and anxiety since long time and was tried upon many drugs with unsatisfactory response and also that zoloft (sertraline) when was given with mirtazepine , and probably she must be on other medicines for physical illness caused her some confusional state and later she relapsed again. probably she has devloped a treatment resistant depression if the drugs were given in adequate dosage and adeqaute time ( atleast 4-6 weeks each) - in such cases the management is done by some alternative methods like combining some antidepressnats from other class, adding antipsychotics drugs like olanzapine,risperidone,aripiprazole etc. or some mood stablisers like lithium/valproate/lamotrigene , thyroid hormones and folate supplements can also be added to antidepressants or electroconvulsive therapy in some cases especially if suicidal ideations or psychotic components are there . even if one antidepressant failed , one can not say that the other will also fail , so trials are needed for better sake of patient- she can also be given psychological treatment like cognitive behavioural therapy from some psychologist in conjunction. so do consult some good psychiatrist and psychologist for evaluation and management. hope i answered your query - if satisfied please rate the answer , any followup queries are welcome