Improving Outcomes in Cancer Patients and the Role of Screening for Cognitive Impairment

Global estimates suggest 17 million people are diagnosed with cancer each year. Up to 80% of these patients report confusion, memory lapses, attention deficits, and an overall feeling of mental fog. Most patients recover within a year of cancer treatment, but up to 35% of cancer survivors continue to experience lasting symptoms. Fortunately, early detection is helping clinicians understand the mechanisms and risk factors underlying cancer-related cognitive impairments. By identifying deficits and introducing tailored therapies as soon as possible, we can offer patients a better long-term prognosis.

How does cancer affect cognition?

Cancer-related cognitive impairment manifests in a number of ways, with potential symptoms including:

• Difficulty focusing and “brain fog”
• Shortened attention span
• Information processing delays
• Memory-related deficits
• Difficulty learning new information
• Inability to organize tasks or multitask

From a testing standpoint, signs of cancer-related cognitive impairment are milder than those seen with people who have dementia or Alzheimer’s disease, but they are no less disruptive to a patient’s quality of life.

Who experiences cognitive impairment with cancer—and why?

The term “chemo brain” is a misnomer, as cognitive impairment can also affect patients undergoing radiation, hormone therapy, bone marrow transplant, and surgery. Patients reporting “a foggy sensation” may notice symptoms resolve within six to 12 months of successful treatment, suggesting that—at least in some capacity—the cognitive impairment is related to the body’s inflammatory response and the cancer itself. Studies show up to one-third of patients exhibit cognitive symptoms even before they receive treatment for their cancer.

In the mid-2000s, animal studies revealed that chemotherapy drugs could pass through the blood-brain barrier. Neuroimaging studies confirmed that chemotherapy patients had to work harder during memory recall tests due to alteration of their neural networks. Other possible mechanisms for cognitive impairment include damage of white and gray matter, as well as vascular changes that restrict blood flow.

Because not all cancer patients undergoing chemotherapy experience cognitive effects, researchers are examining risk based on genetic and lifestyle factors as well. For instance, some studies suggest blood-brain barrier genes may allow or prevent chemotherapies’ access to the brain. The gene ApoE4—also implicated in Alzheimer’s disease risk—is a key gene variant currently being studied. In pediatric patients, nutrition and poverty can be predictors of long-term cognitive functioning. Comorbidities like anxiety, depression, diabetes, hypertension, and chronic fatigue can worsen cognition. The type of cancer, tumor location, and malignancy presumably protect against or predispose a patient to cognitive impairment, though more research is needed.

Screen for cancer-related cognitive impairment with MoCA

Research confirms the wide-ranging impact of cancer on cognitive functioning. Some patients encounter temporary “chemo brain” that improves over time, while others witness progressive decline. For these patients, quality of life suffers and they are at greater risk of mortality. Screening for cancer-related cognitive impairment is the first step to a potentially life-saving intervention.

MoCA has 90% sensitivity and 87% specificity in assessing cognition compared to clinical judgment. MoCA takes just 10 minutes to administer and is available in multiple languages and formats. Versions for those with sight or hearing impairment, low education, and phone or teleconference availability offer clinicians the flexibility they need to assess every patient. The traditional paper test does not assess processing speed, although a new tablet-based app can. All versions of the test cover domains affected by cancer-related cognitive impairment with high validation and correlation compared to the Functional Assessment of Cancer Therapy (FACT).

Multiple peer-reviewed studies validate the use of MoCA to screen for cognitive impairment related to cancer or chemotherapy:

• “Known discrepancies between objective findings and perceived cognitive impairment highlight the importance of utilizing both performance-based measures and self-report measures to identify cognitive problems.” Objective screening for cancer-related cognitive impairment is a necessary first step to providing treatment. After conducting a comprehensive review of scientific literature, researchers concluded that interventions such as cognitive rehabilitation, cognitive behavioral therapy, and mindfulness exercises were effective at improving patient perceptions and objective cognitive functioning.¹
• “One quarter of the five-year breast cancer survivors had a declining trajectory in cognitive performance.” Researchers at the Portuguese Institute of Oncology used MoCA to assess the cognitive function of breast cancer survivors at one year, three years, and five years. They noted two trajectories: some patients declined in cognitive function and others increased. Patients with comorbidities such as anxiety, depression, and poor sleep quality were among the cohort with the greatest need for interventions to prevent and address cognitive decline.²
• “The MoCA test seems to be most relevant to screen for cognitive impairment in older patients with cancer.” In studying 66 patients with cancer who were over 70 years old, clinicians noted a median MoCA score of 24 (on a scale from 8 to 30). Patients were also screened with the MMSE, which was less sensitive in detecting cognitive changes. Over all, 55 patients tested positive on both scores, 32 tested positive on MoCA only, and one patient tested positive with MMSE only.³
• “During the two years following cancer treatment initiation, older patients with a cognitive impairment were up to six times more likely to die than patients without.” For this study, researchers looked at the outcome of 357 patients 65 or older admitted for breast, prostate, or colorectal cancer surgery. Researchers concluded that older patients should be routinely screened for cognitive impairments at the start of their cancer treatment to enable interventions that reduce morbidity and mortality.⁴
• “Probable Cognitive Impairment was as frequent in patients recently diagnosed with Prostate Cancer as in the general population.” More research is needed, but scientists hypothesize that prostate cancer may be associated with a lower prevalence of cognitive impairment compared to other types of cancer.⁵

Treating cognitive impairment leads to better results for patients with cancer

Pharmacological studies have yielded few clues as to how we may boost patients’ cognitive skills. However, Kevin Krull, PhD, a neuroscientist at St. Jude Children’s Research Hospital, has found in preliminary studies that 15-minute sessions of low-voltage transcranial direct current stimulation stimulates the neural network in chemotherapy patients for a two-hour window of cognitive skills training. Patients have shown significant improvements in executive function after just 10 sessions. While this area of research holds promise, more studies are needed to validate its use before it’s offered as a mainstream treatment option.

Other studies have explored positive impact from neural feedback technology, attention retraining, and promotion of healthy lifestyle factors. Krull says what is needed is a multi-pronged approach and use of compensatory strategies—the earlier the better.

“Why do we wait until the problems start?” he asks. “We should be working from a preventative approach and starting to use these technologies to help enhance the skills and functions in those patients before they start experiencing deficits.”

MoCA is a helpful tool to detect symptoms early so an effective treatment regimen may begin. Learn more.

References:

1 Chao, D., Hale, A., Henry, N.L. et al. (2021) Cancer-Related Cognitive Impairment or “Chemobrain:” Emerging Assessments, Treatments, and Targets for Intervention. Curr Phys Med Rehabil Rep. https://doi.org/10.1007/s40141-021-00319-2

2 N Araujo, L Lopes-Conceição, F Fontes, M Severo, T Dias, V Tedim-Cruz, L Ruano, S Pereira, N Lunet, Trajectories of cognitive performance over 5 years in a cohort of breast cancer patients (NEON-BC), European Journal of Public Health, Volume 30, Issue Supplement_5, September 2020, ckaa166.1128, https://doi.org/10.1093/eurpub/ckaa166.1128

3 Rambeau A, Beauplet B, Laviec H, Licaj I, Leconte A, Chatel C, Le Bon P, Denhaerynck J, Clarisse B, Frenkiel N, Lange M, Joly F. Prospective comparison of the Montreal Cognitive Assessment (MoCA) and the Mini Mental State Examination (MMSE) in geriatric oncology. J Geriatr Oncol. 2019 Mar;10(2):235-240. doi: 10.1016/j.jgo.2018.08.003. Epub 2018 Aug 24. PMID: 30150019. https://pubmed.ncbi.nlm.nih.gov/30150019/

4 Libert, Yves, et al. “Vulnerabilities in Older Patients when Cancer Treatment is Initiated: Does a Cognitive Impairment Impact the Two-Year Survival?” PLoS ONE, vol. 11, no. 8, 1 Aug. 2016, p. e0159734. Gale Academic OneFile, Accessed 4 May 2022. link.gale.com/apps/doc/A459740969/AONE?u=googlescholar&sid=bookmark-AONE&xid=974898da.

5 N Araujo, A Costa, L Lopes-Conceição, A Ferreira, F Carneiro, J Oliveira, S Morais, L Ruano, S Pereira, N Lunet, Prevalence of cognitive impairment before treatments for prostate cancer, European Journal of Public Health, Volume 31, Issue Supplement_3, October 2021, ckab165.259, https://doi.org/10.1093/eurpub/ckab165.259

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