Women on tamoxifen often complain of cognitive problems, but in some cases this has been dismissed as "all in their heads." Some recent research comparing tamoxifen to an AI verified this side effect:
"A recent paper has looked at an unusual side effect which has not been greatly appreciated in the past. Many patients who are on adjuvant hormonal therapy complained of cognitive dysfunction, a neuropsychological side effect which can reduce quality of life substantially. Although we have tended to see this more frequently in patients receiving chemotherapy (the so-called 'chemobrain' syndrome), many breast cancer patients receiving hormonal therapy have begun to recognize decreases in memory, decision-making, and ability to comprehension.
This paper has brought significant new information to light regarding these patients. Dr. Christina Schilder and her co-authors from The Netherlands Cancer Institute in Amsterdam (Journal of Clinical Oncology, Volume 28, Pages 1294-1300, 2010), studied patients before hormonal therapy and after receiving either tamoxifen (80 patients), exemestane (99 patients) or healthy control women (120 individuals). They tested patients before and after 1 year of treatment.
The results were very surprising. After 1 year of therapy, breast cancer patients who have received exemestane had neurocognitive performance equal to that of healthy women. However, breast cancer patients who were given tamoxifen had significantly inferior verbal memory, executive mental functioning, and reduced information processing.
These results are significant on many levels for the medical oncology practice. First, women who are considered for tamoxifen therapy should be advised of the potential problems with cognitive functioning and if they observe such problems, should be encouraged to report them to the office. If observed, patients should be considered for switching from tamoxifen to other types of hormonal therapy for treatment of the breast cancer. Continuation of cognitive evaluation and appropriate neuropsychological support should be part of standard practice.
Lastly, there is a grand debate about the adjuvant therapy of post-menopausal women with hormonal responsive tumors. Although many oncologists prefer to initiate therapy for 5 years with aromatase inhibitors, other medical oncologists prefer initiating therapy with tamoxifen followed by a switch to aromatase inhibitors after approximately 2 years. If women are treated for 2 years with tamoxifen, such individuals may develop cognitive dysfunction which can reduce their quality of life prior to the time at which they would switch to an aromatase inhibitor. In contrast, women who initially receive aromatase inhibitors would not be expected to have to suffer from such cognitive dysfunction. This published evidence may add weight to the argument that post-menopausal women should be treated with aromatase inhibitors initially, rather than with a sequence of tamoxifen followed by aromatase inhibitors."