“Chemo Brain” and Alzheimer’s Risk

Up to 70 percent of cancer patients experience cognitive impairment, including diminished memory, reasoning, and multitasking ability [1][2]. The condition is commonly called “chemo brain” or “chemo fog”, even though chemotherapy is unlikely the sole cause of these cognitive problems. The duration of chemo brain can vary from a few weeks to several years [3].

Does having chemo brain increase your risk of developing Alzheimer’s disease? The evidence is mixed. One study of twins found that cancer survivors were more likely than their twins without cancer to have cognitive dysfunction [4]. A study of breast cancer patients reported that in the long-run, dementia diagnoses were more common in women who had chemotherapy treatment than those who had not [5]. But, another study showed an association between a history of cancer and a reduced risk of Alzheimer’s disease [6]. And many other studies show no significant associations between a history of cancer and dementia risk [3][7-9]. There are many factors to consider in these studies, such as the kind of cancer, types of treatment, the dose and length of treatment, preexisting cognitive status, and survival rate of cancer patients. The adverse biological effects of cancer itself can also play a role in Alzheimer’s risk.

More studies are needed to determine the long-term relationships among cancer, cancer treatments, and cognitive dysfunction. Clinical trials are underway to test whether docosahexaenoic acid (DHA) [10] or nicotine patches [11] may prevent or reduce cognitive dysfunction in patients receiving chemotherapy. People experiencing chemo brain should notify their doctor and monitor their symptoms, as the impacts vary widely by person and by treatment. Some strategies to manage chemo brain include getting enough rest, exercising regularly, and using a daily planner or smart phone to keep track of your schedule. These recommendations and other information regarding chemo brain can be found at the American Cancer Society.

1. Jean-Pierre P, McDonald BC (2016) Neuroepidemiology of cancer and treatment-related neurocognitive dysfunction in adult-onset cancer patients and survivors. Handb Clin Neurol  138, 297-309.
2. Raffa RB (2013) Cancer 'survivor-care': II. Disruption of prefrontal brain activation top-down control of working memory capacity as possible mechanism for chemo-fog/brain (chemotherapy-associated cognitive impairment). J Clin Pharm Ther  38, 265-268.
3. Small BJ, Scott SB, Jim HS et al. (2015) Is Cancer a Risk Factor for Cognitive Decline in Late Life? Gerontology  61, 561-566.
4. Heflin LH, Meyerowitz BE, Hall P et al. (2005) Cancer as a risk factor for long-term cognitive deficits and dementia. J Natl Cancer Inst  97, 854-856.
5. Heck JE, Albert SM, Franco R et al. (2008) Patterns of dementia diagnosis in surveillance, epidemiology, and end results breast cancer survivors who use chemotherapy. J Am Geriatr Soc  56, 1687-1692.
6. Roe CM, Fitzpatrick AL, Xiong C et al. (2010) Cancer linked to Alzheimer disease but not vascular dementia. Neurology  74, 106-112.
7. Sun LM, Chen HJ, Liang JA et al. (2016) Long-term use of tamoxifen reduces the risk of dementia: a nationwide population-based cohort study. QJM  109, 103-109.
8. Ording AG, Jensen AB, Cronin-Fenton D et al. (2013) Null association between tamoxifen use and dementia in Danish breast cancer patients. Cancer Epidemiol Biomarkers Prev  22, 993-996.
9. Baxter NN, Durham SB, Phillips KA et al. (2009) Risk of dementia in older breast cancer survivors: a population-based cohort study of the association with adjuvant chemotherapy. J Am Geriatr Soc  57, 403-411.
10. Fabian C Docosahexaenoic Acid (DHA) To Prevent Development of Cognitive Dysfunction Due to Chemotherapy. ClinicalTrialsgov.
11. Newhouse PA Nicotinic Treatment of Post-Chemotherapy Subjective Cognitive Impairment: A Pilot Study. ClinicalTrialsgov.

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