Hello Stu: I noticed this is your first post here on PC. So... welcome to PsychCentral. One other forum, here on PC, that may be of interest would be the partners of people & caregivers forum. Here's a link:

https://forums.psychcentral.com/part...ivers-support/

I can't speak to the problem you've observed other than to say that I've been on a number of different antidepressants over the years (as well as a few other med's) & they've all made me groggy to one degree or another. I think the important thing here would be for your friend to talk with her prescriber about what she is experiencing.

Here are links to 3 articles, from PsychCentral's archives, on the subject of cognitive function & bipolar disorder plus 4 articles that might be of interest to your friend on living with bipolar disorder:

What is 'Cognitive Function'? | Bipolar Laid Bare

Remembering to Remember with Bipolar Disorder | Bipolar Laid Bare

What's the word for brain fog? | Bipolar Laid Bare

In-Depth: Living with Bipolar Disorder

https://psychcentral.com/lib/the-4-k...dium=popular17

https://psychcentral.com/lib/10-smal...olar-disorder/

https://psychcentral.com/blog/the-bi...olar-disorder/

I hope you find PC to be of benefit.