Cognitive rehabilitation for cancer-related cognitive dysfunction: a systematic review

PURPOSE

Individuals with non-central nervous system (CNS) cancers can experience cancer-related cognitive dysfunction (CRCD), negatively impacting daily functioning and quality of life. This systematic review examined cognitive rehabilitation programs aimed at improving cognitive function.

METHODS

PsychInfo and PubMed were searched in February 2019. Eligible studies evaluated a cognitive rehabilitation program for adults with non-CNS cancers and included at least one objective cognitive measure. Across studies, we assessed methodological quality using relevant criteria based on published intervention-related review guidelines and examined findings from performance-based and self-reported outcome measures.

RESULTS

19 studies met inclusion criteria, totalling 1124 participants altogether. These studies included randomized controlled trials (n = 12), partial, quasi or non-randomized controlled trials (n = 3) and single-arm pilot studies (n = 4). All studies found improvements on at least one cognitive measure (performance-based or self-reported). By cognitive domain, objective improvements in memory were most commonly reported, followed by executive functions and processing speed. In terms of methodological quality, studies generally provided clear descriptions of participants and interventions. However, limitations included lack of standardized terminology for interventions, discrepancies in outcome measures, and incomplete statistical reporting.

CONCLUSIONS

The available evidence supports clinical implementation of cognitive rehabilitation to improve CRCD, with further work in program development, dissemination, and feasibility recommended. We provide specific recommendations to facilitate future research and integration in this field.

Neurocognitive Function in Adult Cancer Patients

Impaired neurocognitive function is an increasingly recognized morbidity in patients who have cancer. Cancer treatments, psychosocial stressors, and the malignancy itself can alter brain function. The mechanisms by which this occurs are under active investigation. Although there is a growing appreciation of its prevalence and causes, there remain limited therapeutic options for the treatment of neurocognitive dysfunction in this population. A persistent scientific and clinical effort to understand its mechanisms and impact is critical to the care of oncology patients.

Brain connectivity tracks effects of chemotherapy separately from behavioral measures

Several studies in cancer research have suggested that cognitive dysfunction following chemotherapy, referred to in lay terms as "chemobrain", is a serious problem. At present, the changes in integrative brain function that underlie such dysfunction remain poorly understood. Recent developments in neuroimaging suggest that patterns of functional connectivity can provide a broadly applicable neuromarker of cognitive performance and other psychometric measures. The current study used multivariate analysis methods to identify patterns of disruption in resting state functional connectivity of the brain due to chemotherapy and the degree to which the disruptions can be linked to behavioral measures of distress and cognitive performance. Sixty two women (22 healthy control, 18 patients treated with adjuvant chemotherapy, and 22 treated without chemotherapy) were evaluated with neurocognitive measures followed by self-report questionnaires and open eyes resting-state fMRI scanning at three time points: diagnosis (M0, pre-adjuvant treatment), 1 month (M1), and 7 months (M7) after treatment. The results indicated deficits in cognitive health of breast cancer patients immediately after chemotherapy that improved over time. This psychological trajectory was paralleled by a disruption and later recovery of resting-state functional connectivity, mostly in the parietal and frontal brain regions. Mediation analysis showed that the functional connectivity alteration pattern is a separable treatment symptom from the decreased cognitive health. Current study indicates that more targeted support for patients should be developed to ameliorate these multi-faceted side effects of chemotherapy treatment on neural functioning and cognitive health.

Cognitive Changes in Cancer Survivors

Advances in cancer treatments have led to substantially improved survival for patients with cancer. However, many patients experience changes in cognition as a side effect of both cancer and cancer treatment. This occurs with both central nervous system (CNS) tumors and non-CNS tumors and in both children and adults. Studies of patients with non-CNS cancer have shown that cancer-related cognitive impairment (CRCI), which can include changes in memory, executive function, attention, and processing speed, occurs in up to 30% of patients prior to any treatment and in up to 75% of patients during treatment. A subset of patients with non-CNS and CNS cancer appear to be at higher risk for CRCI, so much research has gone into identifying who is vulnerable. Risk factors for CRCI in adults include cognitive reserve, age, genetic factors, and ethnicity; risk factors for children include genetic factors, female sex, younger age at diagnosis, chemotherapy dose, and both dose and field size for radiation. Although the field has made substantial strides in understanding and treating CRCI, more research is still needed to improve outcomes for both pediatric and adult cancer survivors.