Yes, citalopram (Lexapro™) can cause cognitive problems, but so does depression.

https://www.ncbi.nlm.nih.gov/pubmed/21786537

Also, as we age we have more problem remembering, so what could be occurring with you could be any, all, or none of these. The best way to counteract cognitive deficits is to use your brain. Do crossword puzzles, sudoku, or games where you have to keep words or ideas in your short term memory. This has helped many people I know.

I would not recommend ginkgo biloba, a vasodilator, as it can bring on a stroke if you have aneurysm, in blood vessels in the brain.