Joyce MacKenzie

Cognitive effects of chemotherapy in post-menopausal breast cancer patients 1 year after treatment.

Objective: Studies in breast cancer patients indicate that chemotherapy may cause subtle cognitive disturbances in some women, but the course is unclear. The current study evaluated the cognitive effects of adjuvant chemotherapy in post‐menopausal breast cancer patients 1 year following completion of treatment.

Cognitive effects of hormonal therapy in early stage breast cancer patients: a prospective study

Objective: The primary purpose of this study was to evaluate the cognitive effects of adjuvant hormonal therapies in breast cancer patients.

Cognitive effects of chemotherapy in breast cancer patients: a dose–response study†

The purpose of this study was to determine if cognition progressively worsens with cumulative chemotherapy exposure. We reasoned that the demonstration of such a ‘dose–response’ relationship would help to establish whether cognitive changes are caused by neurotoxic effects of chemotherapy or whether they are due to other confounding factors such as mood and pre‐treatment differences in cognition.

Pre-Chemotherapy Differences in Visuospatial Working Memory in Breast Cancer Patients Compared to Controls: An fMRI Study

Introduction: Cognitive deficits are a side-effect of chemotherapy, however pre-treatment research is limited. This study examines neurofunctional differences during working memory between breast cancer (BC) patients and controls, prior to chemotherapy. Methods: Early stage BC females (23), scanned after surgery but before chemotherapy, were individually matched to non-cancer controls. Participants underwent functional magnetic resonance imaging (fMRI) while performing a Visuospatial N-back task and data was analyzed by multiple group comparisons. fMRI task performance, neuropsychological tests, hospital records, and salivary biomarkers were also collected. Results: There were no significant group differences on neuropsychological tests, estrogen, or cortisol. Patients made significantly fewer commission errors but had less overall correct responses and were slower than controls during the task. Significant group differences were observed for the fMRI data, yet results depended on the type of analysis. BC patients presented with increased activations during working memory compared to controls in areas such as the inferior frontal gyrus, insula, thalamus, and midbrain. Individual group regressions revealed a reverse relationship between brain activity and commission errors. Conclusion: This is the first fMRI investigation to reveal neurophysiological differences during visuospatial working memory between BC patients pre-chemotherapy and controls. These results also increase the knowledge about the effects of BC and related factors on the working memory network. Significance: This highlights the need to better understand the pre-chemotherapy BC patient and the effects of associated confounding variables.

A prospective study of grey matter and cognitive function alterations in chemotherapy-treated breast cancer patients

PurposeSubsequent to chemotherapy treatment, breast cancer patients often report a decline in cognitive functioning that can adversely impact many aspects of their lives. Evidence has mounted in recent years indicating that a portion of breast cancer survivors who have undergone chemotherapy display reduced performance on objective measures of cognitive functioning relative to comparison groups. Neurophysiological support for chemotherapy-related cognitive impairment has been accumulating due to an increase in neuroimaging studies in this field; however, longitudinal studies are limited and have not examined the relationship between structural grey matter alterations and neuropsychological performance. The aim of this study was to extend the cancer-cognition literature by investigating the association between grey matter attenuation and objectively measured cognitive functioning in chemotherapy-treated breast cancer patients.MethodsFemale breast cancer patients (n = 19) underwent magnetic resonance imaging after surgery but before commencing chemotherapy, one month following treatment, and one year after treatment completion. Individually matched controls (n = 19) underwent imaging at similar intervals. All participants underwent a comprehensive neuropsychological battery comprising four cognitive domains at these same time points. Longitudinal grey matter changes were investigated using voxel-based morphometry.ResultsOne month following chemotherapy, patients had distributed grey matter volume reductions. One year after treatment, a partial recovery was observed with alterations persisting predominantly in frontal and temporal regions. This course was not observed in the healthy comparison group. Processing speed followed a similar trajectory within the patient group, with poorest scores obtained one month following treatment and some improvement evident one year post-treatment.ConclusionThis study provides further credence to patient claims of altered cognitive functioning subsequent to chemotherapy treatment.

Persistent cognitive changes in breast cancer patients 1 year following completion of chemotherapy.

Numerous studies have shown that there are acute cognitive side-effects of chemotherapy for breast cancer. Presumably, patients are more concerned about chronic treatment effects. This report from a prospective longitudinal study compares cognitive functioning in 56 breast cancer patients 1 year after chemotherapy to that of 56 healthy individuals. Neuropsychological test scores were combined into verbal memory, visual memory, working memory, and processing speed scores, as well as an overall summary score, and analyzed using multi-level growth modeling. Frequency of cognitive decline was assessed using regression-based change scores. There was significant rebound in the overall summary score from end of treatment to 1-year follow-up as well as a substantial reduction in the frequency of cognitive decline. However, more than one-third of the breast cancer patients who showed cognitive decline immediately following completion of chemotherapy showed persistent cognitive decline 1 year later. Furthermore, recovery was not seen in all cognitive domains. In fact, the rebound was significant only for working memory. Longer multi-site studies are recommended to explore the risk factors for and the permanence of these longer-term cognitive effects.

Study of the cognitive effects of chemotherapy: considerations in selection of a control group.

Neuropsychological data collected in 28 breast cancer patients before and after chemotherapy were compared to those of a local healthy control group, a local disease control group, and published norms, respectively, in order to determine whether the nature of the control group influenced outcome. The frequency of decline in the chemotherapy group was 21% and significantly higher than that of the control group whether referenced to the healthy controls, disease controls, or published norms. These results suggest that published norms may be adequate to demonstrate cancer-related cognitive impairment provided that cognitive function is measured adequately, practice effects and base rates are taken into account, and demographic factors that might influence practice effects are considered.

Metamemory function in chemotherapy‐treated patients with breast cancer: an explanation for the dissociation between subjective and objective memory measures?

The purpose of this study was to determine if a deficit in metamemory could account for the disparity between subjective and objective measures of memory function commonly observed in patients with breast cancer (BC). Metamemory refers to the awareness and management of ones own memory function. It is considered an aspect of executive functioning, one of the most common areas of cognitive compromise associated with BC and its treatment.