From the Journals

Exercise intolerance linked to neurocognitive dysfunction in ALL



Exercise intolerance was associated with worse neurocognitive function in adult survivors of pediatric acute lymphoblastic leukemia (ALL), according to results from a cross-sectional study.

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The findings suggest additional research is needed to better understand the effects of increased exercise capacity on neurocognitive performance in these patients.

“We used a clinically assessed cohort of childhood cancer survivors participating in the St. Jude Lifetime cohort study to determine whether exercise intolerance, expressed as decreased oxygen uptake, is associated with neurocognitive impairments in long-term survivors of childhood ALL and evaluated whether exercise intolerance mediates the association between chronic cardiac or pulmonary conditions and neurocognitive impairment,” wrote Nicholas S. Phillips, MD, PhD, of St. Jude Children’s Research Hospital in Memphis, Tenn., and colleagues. The results were published in Cancer.

The cross-sectional cohort study included 341 young adult survivors of pediatric ALL and 288 evaluable control participants. Survivors were recruited from 1980 to 2003.

Eligible participants were 18 years or older, and remained alive for a minimum of 5 years post ALL diagnosis. Control subjects were non–first-degree relatives of ALL survivors.

The researchers evaluated exercise capacity using cardiopulmonary exercise testing, expressed as relative peak volume of oxygen (rpkVO2) max scores. Other tests included self-rated questionnaires, as well as a standardized neuropsychological evaluation.

After analysis, the researchers found that ALL survivors had lower mean rpkVO2 scores, compared with control participants (23.45 vs. 33.03 mL/kg per min; P less than .001).

Survivors also had worse performance on several measures of neurocognitive function, including working memory, verbal intelligence, visual-motor speed, and other math and reading domains, compared with controls (all P less than .001).

The researchers also performed a multivariable analysis and found that a 1-unit metabolic equivalent increase in exercise tolerance was associated with significantly increased performance in some neurocognitive measures, including attention, verbal ability, verbal fluency, motor speed, and academics.

“Our research suggests that a minor improvement in exercise tolerance, such as going from sitting on the couch and watching TV, to walking around the block for 30 minutes a day, can have a significant impact on survivors’ intellectual health,” Dr. Phillips said in a statement.

The researchers noted that recent evidence has shown that structured exercise training may benefit younger survivors. “These studies demonstrate that a low-cost, home-based exercise training program can effectively increase cardiopulmonary fitness during and after completion of therapy,” they wrote.

The team acknowledged a key limitation of the study was the cross-sectional design. As a result, the direction of these associations remains unknown, and warrants future study.

The study was supported by the National Institutes of Health and the American Lebanese Syrian Associated Charities. The researchers did not report conflicts of interest.

SOURCE: Phillips NS et al. Cancer. 2019 Oct 21. doi: 10.1002/cncr.32510.

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