Neural Health, Depression, and Fatigue in Cancer Survivors Enrolled in a Structured Exercise Rehabilitation Program

Abstract

ObjectiveThe purpose of this cross‐sectional study was to explore relationships between biomarkers of neural health, including brain‐derived neurotrophic factor (BDNF) and nerve growth factor (NGF), cardiorespiratory fitness and muscular strength, and depression, fatigue, and quality of life (QOL) in cancer survivors who are currently receiving either chemotherapy and/or radiation treatments (TM), or not receiving treatment (NT), while enrolled in a structured exercise program.MethodsPhysically active cancer survivors were recruited from the University of Northern Colorado Cancer Rehabilitation Institute. Age, height, weight, and body fat percentage (BF%) were obtained, and cardiorespiratory fitness and muscular strength were evaluated using peak oxygen uptake (VO2 peak) and estimated one‐repetition maximum, respectively. Depression, fatigue, and QOL were evaluated with the Beck Depression Inventory, Revised Piper Fatigue Scale, and Ferrans and Powers QOL Index Version III Questionnaire. Rested and fasted plasma BDNF and NGF concentrations were obtained using enzyme‐linked immunosorbent assays. Differences between groups were evaluated using an unpaired t‐test, and Pearson’s correlation was used to determine the relationship between BDNF and NGF, and cardiorespiratory fitness, muscular strength, and questionnaire scores. Data are presented as mean ± standard deviation and significance was defined as P < 0.05.ResultsTwenty‐four cancer survivors participated in the study and were divided into TM (n=12) and NT (n=12) groups. Time since treatment for NT was 10.2±8.6 months. No significant differences were observed between groups in physical characteristics, fitness measures, or survey scores. When all participants were grouped together, characteristics were age: 65.2±12.9 y, height: 167.1±8.0 cm, weight: 79.8±16.6 kg, BF%: 36.7±9.6%, VO2 peak: 25.8±6.9 mL/min/kg, chest press: 37.0±15.9 kg, leg press: 103.7±38.1 kg, depression score: 5.7±3.8, fatigue score: 3.2±2.2, and QOL score: 23.8±2.9. Concentrations of BDNF were significantly lower in TM (85.1±27.9 pg/mL) compared to NT (141.3±68.2 pg/mL; P=0.01); however, when TM and NT were combined, mean NGF concentrations were 5.0±0.7 pg/mL and there were no significant differences between TM and NT groups. Concentrations of BDNF and NGF were not associated with measures of cardiorespiratory fitness or muscular strength, or with depression, fatigue, or QOL.ConclusionsConcentrations of BDNF were significantly lower in physically active cancer survivors currently undergoing cancer‐related treatment. Although these cancer survivors were participating in structured exercise, which is known to increase circulating BDNF concentrations, these rehabilitation programs may not completely protect individuals against cancer‐related treatment reductions in BDNF.Support or Funding InformationUniversity of Northern Colorado Faculty Research and Development Program