Endocrine Aspects of Healthy Brain Aging

Mediators of a Physical Activity Intervention on Cognition in Breast Cancer Survivors: Evidence From a Randomized Controlled Trial

Background

Emerging research suggests that increasing physical activity can help improve cognition among breast cancer survivors. However, little is known about the mechanism through which physical activity impacts cancer survivors’ cognition.

Objective

The objective of this secondary analysis examined physical and psychological function potentially linking physical activity with changes in cognition among breast cancer survivors in a randomized controlled trial where the exercise arm had greater improvements in cognition than the control arm.

Methods

A total of 87 sedentary breast cancer survivors were randomized to a 12-week physical activity intervention (n=43) or control condition (n=44). Objectively measured processing speed (National Institutes of Health Toolbox Oral Symbol Digit), self-reported cognition (patient-reported outcomes measurement information system [PROMIS] cognitive abilities), PROMIS measures of physical and psychological function (depression, anxiety, fatigue, and physical functioning), and plasma biomarkers (brain-derived neurotrophic factor, homeostatic model assessment 2 of insulin resistance, and C-reactive protein [CRP]) were collected at baseline and 12 weeks. Linear mixed-effects models tested intervention effects on changes in physical and psychological function variables and biomarkers. Bootstrapping was used to assess mediation. Exploratory analyses examined self-reported cognitive abilities and processing speed as mediators of the intervention effect on physical functioning.

Results

Participants in the exercise arm had significantly greater improvements in physical functioning (beta=1.23; 95% CI 2.42 to 0.03; P=.049) and reductions in anxiety (beta=−1.50; 95% CI −0.07 to −2.94; P=.04) than those in the control arm. Anxiety significantly mediated the intervention effect on cognitive abilities (bootstrap 95% CI −1.96 to −0.06), whereas physical functioning did not (bootstrap 95% CI −1.12 to 0.10). Neither anxiety (bootstrap 95% CI −1.18 to 0.74) nor physical functioning (bootstrap 95% CI −2.34 to 0.15) mediated the intervention effect on processing speed. Of the biomarkers, only CRP had greater changes in the exercise arm than the control arm (beta=.253; 95% CI −0.04 to 0.57; P=.09), but CRP was not associated with cognition; therefore, none of the biomarker measures mediated the intervention effect on cognition. Neither cognitive abilities (bootstrap 95% CI −0.06 to 0.68) nor processing speed (bootstrap 95% CI −0.15 to 0.63) mediated the intervention effect on physical function.

Conclusions

Physical activity interventions may improve self-reported cognition by decreasing anxiety. If supported by larger studies, reducing anxiety may be an important target for improving self-reported cognition among cancer survivors.

Trial Registration

ClinicalTrials.gov NCT02332876; https://clinicaltrials.gov/ct2/show/NCT02332876

Impact of increasing physical activity on cognitive functioning in breast cancer survivors: Rationale and study design of Memory & Motion

INTRODUCTION

Many breast cancer survivors experience problems with cognitive functioning that can persist years after treatment. Increasing physical activity has been shown to improve cognitive functioning in healthy and cognitively impaired adults, but has not yet been tested in cancer survivors. The primary aim of this randomized controlled trial is to examine the effects of a 3-month physical activity intervention compared to a waitlist Control arm on neuropsychological outcomes and subjective cognitive concerns in breast cancer survivors.

METHODS

Eighty sedentary breast cancer survivors, self-reporting difficulties with cognition, will be randomized into an Exercise arm or Control arm. The Exercise arm includes an activity tracker (i.e., a Fitbit), phone calls, plus tailored and non-tailored email content. The Control arm will receive emails on women's health topics on the same schedule as the Exercise arm. Assessments conducted at baseline and 3 months include: neuropsychological testing, cognitive concerns and other aspects of quality of life, and 7 days of a hip-worn accelerometer. Participants will also provide fasting blood draws to assess brain-derived neurotropic factor, Insulin-like growth factor 1, insulin resistance, and C-reactive protein. Primary and secondary outcomes are changes in neuropsychological testing and cognitive concerns. Biomarkers will be examined to further understand the underlying relationship between physical activity and cognition.

CONCLUSION

The Memory & Motion study is designed to test whether increasing physical activity can improve cognitive functioning in breast cancer survivors. Results from this study could be used to guide development of interventions to improve cognitive functioning in breast cancer survivors.

Hypothalamic-pituitary dysfunction following traumatic brain injury affects functional improvement during acute inpatient rehabilitation

OBJECTIVE

To evaluate the occurrence of hypothalamic-pituitary dysfunction following a traumatic brain injury (TBI) and to determine its effect on functional improvement in acute inpatient rehabilitation.

METHODS

A retrospective chart review identified male patients with a primary diagnosis of TBI with or without a skull fracture, an onset date within 6 months prior to admission, and were 16 years of age or older. The percentage of individuals in this population with abnormal hormone levels was determined on the basis of the established normal reference range for each hormone assay. The functional independence measure, which assesses functional outcomes in acute inpatient rehabilitation, was used to examine the relationship between hormone levels and functional improvement.

RESULTS

Hypothalamic-pituitary dysfunction was identified in nearly 70% of men following TBI. Hypogonadism, or low testosterone levels, was observed in 66% of the patients, followed by low levels of free T4 in 46% and low levels of insulin growth factor-1 in 26% of patients. Hypopituitarism associated with impaired functional recovery. Specifically, the functional independence measure change per day was significantly lower in patients with low levels of testosterone and insulin growth factor-1.

CONCLUSIONS

These findings suggest the importance of testosterone and insulin growth factor-1 activity in the early stages of physical and cognitive rehabilitation.

Revitalizing the aged brain

Optimal cognitive and emotional function is vital to independence, productivity, and quality of life. Cognitive impairment without dementia may be seen in 16% to 33% of adults older than 65 years, and is associated with significant emotional distress. Cognitive and emotional well-being are inextricably linked. This article qualifies revitalizing the aged brain, discusses neuroplasticity, and suggests practical neuroplasticity-based strategies to improve the cognitive and emotional well-being of older adults.