Persistent Brain Fog After Breast Cancer: What Researchers Are Investigating

Completing cancer treatment can bring relief, but some survivors continue to struggle with everyday mental tasks. Remembering appointments, following conversations, or concentrating on work may require more effort than before their diagnosis. These changes can be distressing, particularly when they persist after other treatment-related symptoms have improved. Scientists are looking for better ways to address these difficulties, and a recent clinical investigation at UCLA Health has examined whether a naturally occurring compound called oxaloacetate could have a role.

Oxaloacetate participates in the chemical reactions cells use to generate energy. Researchers became interested in its potential effects on cognitive health because it is involved in metabolic processes that may influence brain function. To explore its possible benefits, investigators studied women who continued to report substantial cognitive difficulties after treatment for early-stage breast cancer. The trial was designed to assess both whether participants experienced changes and whether the supplement appeared tolerable over the study period.

Eighteen women entered the trial, and 16 completed the eight-week intervention. Participants received 500 milligrams of oxaloacetate twice a day. By the end, the women who completed the intervention reported notable improvements in their perceived cognitive difficulties. Assessments also suggested changes in certain mental skills, including processing information and managing complex tasks. Fatigue and physical functioning improved as well. Although these observations provide a reason to continue investigating the compound, they do not establish that it will produce the same results for other patients.

There are still significant gaps in the evidence. The researchers did not compare the supplement against a placebo group, making it difficult to separate a treatment effect from other influences on participants' symptoms.

The trial was also too small to determine reliably which patients might benefit most. Digestive problems were the main tolerability concern, and two participants stopped taking the supplement because of gastrointestinal symptoms. A larger, controlled study will be needed to determine whether the apparent improvements can be reproduced and whether the benefits outweigh the risks.

For breast cancer survivors experiencing ongoing concentration or memory difficulties, the findings offer a potential direction for future research, not an established treatment recommendation.

Cognitive changes can have several contributing factors, including poor sleep, fatigue, medications, hormonal changes, and emotional stress. Assessment by a healthcare professional can help identify factors that may be addressed.

Before trying oxaloacetate or other products marketed for cognitive support, discuss the decision with your oncology team. A board-certified physician can also help with general health concerns and appropriate next steps in your care.

References

• Ganz, P. A., et al. Results From a Phase II Single-Arm Trial Evaluating the Safety and Efficacy of Anhydrous Enol-Oxaloacetate on Improving Cognitive Complaints in Breast Cancer Survivors. JCO Oncology Advances. October 20, 2026.

• UCLA Health. Nutritional Supplement May Help Ease “Brain Fog” After Breast Cancer Treatment. October 20, 2026.

• National Cancer Institute. Cognitive Impairment in Adults With Cancer.