Brief Answer:
need to stop ambien, thorough evaluation needed

Detailed Answer:
Dear Ma'am,

Thank you for your query. In most cases, attention and concentration problems mimic as memory impairment, particularly in the elderly. There can be many causes for attention problems, like impaired or poor quality of sleep, depression, anxiety, stress etc. Since you complain of sleep issues for long duration, it may be the real culprit behind your symptoms.Ambien (containes Zolpidem) if taken for long duration can also cause attention problems. Also, your history shows you are on Celexa, an antidepressant. If your underlying depression or anxiety has worsened, that may also give rise to your complaints.
Finally, you are also on Donepezil, a drug used to treat dementia or mild cognitive impairment. If you have any of these, then there is likely to be real deficit in your memory (not just an attention problem).

Whatever may be the cause, If a patient with your complaint would have come to me, I would have first referred her for a neuropsychological evaluation to evaluate objective memory, attention and other higher mental functions. the results would have provided clue about the problem- due to attention or really a memory impairment.
In case of attention and concentration problems, I would have suggested maintaining adequate sleep hygiene, relaxation techniques, and stopping the Ambien. I would have suggested an alternate drug like Trazodone or Etizolam for improving sleep quality.
In case of memory impairment, it would require a further thorough diagnostics and formulation of an appropriate treatment plan (usually involving drugs like donepezil, memantine etc).
I would advice you to consult a psychiatrist for thorough evaluation and management of your condition. As you are on multiple psychotropic agents, I would suggest you consult a specialist instead of self experimentation.
Hope I've been able to satisfy your query. Please contact me if you require any further clarifications, otherwise close the discussion and rate the same.

Thank you,
Dr. Sourav.

---

Brief Answer:
usually around 3 months

Detailed Answer:
Dear Ma'am,

Thank you for your query. Dementia is a chronic progressive (deteriorating) illness in most cases. If someone is prescribed donepezil for a diagnosis of dementia, in about 1/3 rd to half of the cases, some improvement is noticeable within the first 2-3 months. In about 1/3 rd cases, no significant improvement occurs, but further deterioration is prevented. In the remaining 1/3 of the cases, mild deterioration of symptoms still continue.

However, in case of Mild Cognitive Impairment, improvements are noticeable by around 2-3 months.

Also, dose titration is required depending upon response for the first few months.
One important point to note is that these improvements are mostly noticeable first by the care givers and family members than the patient himself/ herself.

Hope I've been able to satisfy your query. Please contact me if you require any further clarifications, otherwise close the discussion and rate the same.

Thank you,
Dr. Sourav.

---