The fog hasn't lifted on "chemobrain" yet: ongoing uncertainty regarding the effects of chemotherapy and breast cancer on cognition

Doxorubicin treatment has a biphasic effect over time on dopamine release and impulsive behavior in Wistar rats

Doxorubicin (Dox) is a chemotherapy agent commonly used to treat multiple types of cancers and is associated with cognitive impairment. The goal of this work was to determine the effect of Dox treatment on dopamine release and uptake and behavior in rats. Rats received one dose per week of Dox (2.5 mg/kg, I.V.) and were sacrificed after two or four weeks. Dopamine release and uptake was measured in brain slices with fast-scan cyclic voltammetry (FSCV). A set of rats that received treatment also underwent behavioral testing with the 5-choice serial reaction timed task (5CSRTT) to measure degree of impulsiveness and attention throughout the course of treatment. Dopamine release and uptake increased substantially after treatment with Dox for two weeks compared to controls. After four weeks of treatment, release levels decreased to less than controls while there were no differences in uptake. Treatment of brain slices with pramipexole revealed that dopamine release was equally sensitive to autoregulation after two weeks of Dox treatment, but less sensitive after four weeks. Measurements from the 5CSRTT indicated that, while Dox did not affect attention, it increased impulsiveness after two and three weeks of treatment, but not after four weeks. Treatment with Dox for a short time may elevate dopamine system activity and increase impulsiveness, while longer administration then leads to an underactive dopamine system. To our knowledge this work demonstrates for the first time that Dox can have a biphasic neurochemical and behavioral effect.

Study of Chemotherapy-Induced Cognitive Impairment in Women with Breast Cancer

Background: Oncology patients experience a large number of symptoms and, those referring to cognitive performance has an ever-increasing importance in clinical practice, due to the increase in survival rates and interest in the patient’s quality of life. The studies reviewed showed that chemotherapy-related cognitive impairment might occur in 15 and 50% of oncology patients. The main objective of this research was to study the impact of chemotherapy on the cognitive function of patients with locoregional breast cancer. Method: Analytical, prospective, longitudinal study using three measures, unifactorial intrasubject design, non-probability, and random selection sampling. The sample comprised women newly diagnosed with locoregional breast cancer in stages I, II, IIIA who received chemotherapy at the University Hospital of Salamanca (Complejo Asistencial Universitario de Salamanca), randomly selected for three years. Semi-structured interviews were conducted, and anxiety and depression (Hospital Anxiety and Depression scale, HAD); quality of life (QLQ-BR23 scale) and the following cognitive variables were assessed—processing speed, attention, memory, and executive functions (subtests of the Wechsler Intelligence Scale and the Trail Making Test). Results: The final sample size included 151 participants; 23 were excluded. A decline in cognitive performance was observed in patients, which did not completely recover two months after chemotherapy was completed. Additionally, worse cognitive performance was observed in patients with anxious or depressive symptoms. There was a negative impact on the quality of life. Conclusion: Chemotherapy had an impact on the cognitive performance of oncology patients in most cognitive domains studied.

Cognitive rehabilitation program to improve cognition of cancer patients treated with chemotherapy: A 3-arm randomized trial

Background

There is no treatment for cancer‐related cognitive impairment, an important adverse effect that negatively impacts quality of life (QOL). We conducted a 3‐arm randomized controlled trial to evaluate the impact of computer‐assisted cognitive rehabilitation (CR) on cognition, QOL, anxiety, and depression among cancer patients treated with chemotherapy.

Methods

Patients who reported cognitive complaints during or after completing chemotherapy were randomly assigned to 1 of 3 12‐week CR programs: computer‐assisted CR with a neuropsychologist (experimental group A), home cognitive self‐exercises (active control group B), or phone follow‐up (active control group C). Subjective cognition was assessed by the Functional Assessment of Cancer Therapy–Cognitive Function (FACT‐Cog), objective cognition was assessed by neuropsychological tests, QOL was assessed by the FACT‐General, and depression and anxiety were assessed by psychological tests. The primary endpoint was the proportion of patients with a 7‐point improvement in the FACT‐Cog perceived cognitive impairment (PCI) score.

Results

Among the 167 enrolled patients (median age, 51 years), group A had the highest proportion of patients with a 7‐point PCI improvement (75%), followed by groups B (59%) and C (57%), but the difference was not statistically significant (P = .13). Compared with groups B and C, the mean difference in PCI score was significantly higher in group A (P = .02), with better perceived cognitive abilities (P < .01) and a significant improvement in working memory (P = .03). Group A reported higher QOL related to cognition (FACT‐Cog QOL) (P = .01) and improvement in depression symptoms (P = .03).

Conclusions

These results suggest a benefit of a computer‐based CR program in the management of cancer‐related cognitive impairment and complaints.

In this 3‐arm randomized clinical trial of 167 patients, computer‐assisted cognitive rehabilitation improved cognitive complaints, with significant improvement in working memory, quality of life related to cognition, and depression symptoms. Computer‐assisted cognitive rehabilitation is a compelling approach toward the management of cancer‐related cognitive impairment and complaints.

Histone deacetylase inhibition is cytotoxic to oligodendrocyte precursor cells in vitro and in vivo

Histone deacetylase (HDAC) inhibition mediated by small molecule HDAC inhibitors (HDACi) has demonstrated divergent effects including toxicity towards transformed cell lines, neuroprotection in neurological disease models, and inhibition of oligodendrocyte precursor cell (OPC) differentiation to mature oligodendrocytes (OL). However, it remains unknown if transient HDAC inhibition may promote OPC survival. Using mouse cortical OPC primary cultures, we investigated the effects of the FDA approved pan-HDACi suberoylanilide hydroxamic acid (SAHA) on OPC survival. Initial studies showed differences in the HDAC expression pattern of multiple HDAC isoforms in OPCs relative to their terminally differentiated progeny cells, OLs and astrocytes. Treatment of OPCs with SAHA for up to 72h using a maximum concentration either at or lower than those necessary for cytotoxicity in most transformed cell lines resulted in over 67% reduction in viability relative to vehicle-treated OPCs. This was at least partly due to increased apoptosis as SAHA-treated cells displayed activated caspase 3 and were protected by the general caspase inhibitor Q-VD-OPH. Additionally, SAHA treatment of whole mice at postnatal day 5 induced apoptosis of cortical OPCs. These results suggest that SAHA negatively impacts OPC survival and may be detrimental to the myelinating brain and spinal cord. Such toxicity may be relevant in a clinical context as SAHA is currently involved in numerous clinical trials and is in consideration for use in the treatment of psychiatric and neurodegenerative conditions.

Long-lasting impairments in adult neurogenesis, spatial learning and memory from a standard chemotherapy regimen used to treat breast cancer

The negative impact of chemotherapy on cognitive function in cancer patients has gained increasing attention in the last decade. Whilst the short-term acute effects on cognition are expected following chemotherapy, the persistence of such impairments in the long-term is still in question. This is despite clinical evidence indicating cognitive difficulties may persist well beyond treatment and affect quality of life. In the present study, we assessed the long-term (3 months) cognitive impact of chemotherapy in a mouse model intended to mimic the human female post-menopausal population receiving chemotherapy for breast cancer. Ovariectomized, female, C57BL/6J mice received two doses of Doxorubicin, Cyclophosphamide, and 5-Fluorouracil or saline vehicle (control), separated by one week. During this interval, mice received BrdU injections to label dividing cells. Results indicate a persistent impairment in learning and recall (1h, 24h and 48h) on the Morris water maze, reduced survival and differentiation of new neurons (BrdU+/NeuN+), and a persistent decline in proliferation of new cells (Ki67(+)) in the dentate gyrus. Locomotor activity, motor performance, and anxiety-like behavior were unaffected. We further evaluated the efficacy of a diet enriched in omega-3-fatty acids (DHA+EPA+DPA), in reversing long-term chemotherapy deficits but no rescue was observed. The model described produces long-term cognitive and cellular impairments from chemotherapy that mimic those observed in humans. It could be useful for identifying mechanisms of action and to test further the ability of lifestyle interventions (e.g., diet) for ameliorating chemotherapy-induced cognitive impairments.

Chemotherapy altered brain functional connectivity in women with breast cancer: a pilot study

Adjuvant chemotherapy is associated with improvements in long-term cancer survival. However, reports of cognitive impairment following treatment emphasize the importance of understanding the long-term effects of chemotherapy on brain functioning. Cognitive deficits found in chemotherapy patients suggest a change in brain functioning that affects specific cognitive domains such as attentional processing and executive functioning. This study examined the processes potentially underlying these changes in cognition by examining brain functional connectivity pre- and post-chemotherapy in women with breast cancer. Functional connectivity examines the temporal correlation between spatially remote brain regions in an effort to understand how brain networks support specific cognitive functions. Nine women diagnosed with breast cancer completed a functional magnetic resonance imaging (fMRI) session before chemotherapy, 1 month after, and 1 year after the completion of chemotherapy. Seed-based functional connectivity analyses were completed using seeds in the intraparietal sulcus (IPS) to examine connectivity in the dorsal anterior attention network and in the posterior cingulate cortex (PCC) to examine connectivity in the default mode network. Results showed decreased functional connectivity 1 month after chemotherapy that partially returned to baseline at 1 year in the dorsal attention network. Decreased connectivity was seen in the default mode network at 1 month and 1 year following chemotherapy. In addition, increased subjective memory complaints were noted at 1 month and 1 year post-chemotherapy. These findings suggest a detrimental effect of chemotherapy on brain functional connectivity that is potentially related to subjective cognitive assessment.

Tibetan sound meditation for cognitive dysfunction: results of a randomized controlled pilot trial

OBJECTIVE

Although chemotherapy-induced cognitive impairment is common among breast cancer patients, evidence for effective interventions addressing cognitive deficits is limited. This randomized controlled trial examined the feasibility and preliminary efficacy of a Tibetan Sound Meditation (TSM) program to improve cognitive function and quality of life in breast cancer patients.

METHODS

Forty-seven breast cancer patients (mean age 56.3 years), who were staged I-III at diagnosis, 6-60 months post-chemotherapy, and reported cognitive impairment at study entry were recruited. Participants were randomized to either two weekly TSM sessions for 6 weeks or a wait list control group. Neuropsychological assessments were completed at baseline and 1 month post-treatment. Self-report measures of cognitive function (Functional Assessment of Cancer Therapy (FACT)-Cog), quality of life (SF-36), depressive symptoms (Center for Epidemiologic Studies Depression Scale), sleep disturbance (Pittsburgh Sleep Quality Index), fatigue (Brief Fatigue Inventory), and spirituality (FACT-Sp) were completed at baseline, the end of treatment, and 1 month later.

RESULTS

Relative to the control group, women in the TSM group performed better on the verbal memory test (Rey Auditory Verbal Learning Test trial 1) (p = 0.06) and the short-term memory and processing speed task (Digit Symbol) (p = 0.09) and reported improved cognitive function (p = 0.06), cognitive abilities (p = 0.08), mental health (p = 0.04), and spirituality (p = 0.05) at the end of treatment but not 1 month later.

CONCLUSIONS

This randomized controlled trial revealed that TSM program appears to be a feasible and acceptable intervention and may be associated with short-term improvements in objective and subjective cognitive function as well as mental health and spirituality in breast cancer patients.

A pilot study of prospective memory functioning in early breast cancer survivors

AIMS

To evaluate prospective memory (PM) functioning in early breast cancer (BC) survivors and its association with fatigue and depression.

METHODS

The Memory for Intention Screening Test, the Center for Epidemiologic Studies Depression Scale and the Functional Assessment of Cancer Therapy-Fatigue subscale were administered to 80 patients and 80 aged-matched healthy controls.

RESULTS

Patients performed more poorly than controls on the memory test (p < 0.001) and had a higher rate of impairment (odds ratio = 5.5, p < 0.01). Fatigue mediated the relationship between Group membership and PM performance.

CONCLUSIONS

BC survivors exhibited a clear pattern of PM deficit and fatigue was a major contributor to this deficit. This suggests that a common mechanism may be involved in fatigue symptoms and memory disturbances experienced by patients. Further research is needed to evaluate the role of adjuvant therapy in PM deficits and to explore whether interventions targeted at improving fatigue may also improve memory functioning in BC survivors.