High-intensity aerobic exercise does not improve cognitive performance in MS

[ActiveMSers]

This is disappointing and surprising, given that HIIT in able-bodied does affect cognition, according to other studies. Looking solely at the abstract on this poster (it has NOT been peer reviewed or accepted into a journal), the study looks solid: it was long enough, it was large enough, and it was randomized. It will be interesting to dive into the details. The last paper this group did had similar negative findings in the abstract, but reviewing the full study revealed significant flaws. Stay tuned. -D

High-intensity aerobic exercise does not improve cognitive performance in people with multiple sclerosis: a randomised controlled trial

M. Langeskov-Christensen1, L. Grøndahl Hvid1, H. Boye Jensen2, H. Hvilsted Nielsen3, T. Petersen4, E. Stenager5, P. Hämäläinen6, U. Dalgas1 1Aarhus University, Aarhus, 2Lillebaelt Hospital, Kolding, 3Odense University Hospital, Odense, 4Aarhus University Hospital, Aarhus, 5Hospital of Southern Denmark, Sønderborg, Denmark, 6Masku Neurological Rehabilitation Centre, Masku, Finland

Introduction: Cognitive impairment is highly prevalent in multiple sclerosis (MS). Progressive aerobic exercise (PAE) represents a promising approach towards preservation or even improvement of cognitive performance in people with MS (pwMS).

Aims: To investigate the effects of PAE on the cognitive domains of information processing, learning and memory, and verbal fluency in pwMS.

Objectives: Cognitive performance data sets was collected pre and post intervention / waitlist control. The data sets were analysed using an intention-to-treat linear mixed effects model with time and group as the factors of interest. Age, sex, education level, Major Depression Inventory (MDI) score, and MS type were a priori classified as important covariates and included in the model.

Methods: This was a randomised controlled cross-over trial, including an exercise (n=43, 24 weeks of supervised PAE followed by self-guided physical activity) and a waitlist group (n=43, 24 weeks of habitual lifestyle followed by supervised PAE). Assessments included The Brief Repeatable Battery of Neuropsychological tests (BRB-N), self-reported mood (MDI), and cardiorespiratory fitness (VO2max). Reference data was used to compute Z-scores for BRB-N scores. Cognitive impairment was defined as one or more Z-scores ≤-1.5 standard deviation. ClinicalTrials.gov (https://clinicaltrials.gov/) identifier: NCT0266155

Results: No between-group changes in the total group or in the cognitively impaired subgroup were observed in scores of the BRB-N following the 24-week intervention period. Cardiorespiratory fitness increased significantly in the exercise group (between-group change and 95% confidence interval of +3.5 (2.0;5.1) mLO2/min/kg, p< 0.01). Exercise adherence was excellent with 44.8 ± 2.6 completed sessions, corresponding to 93.3 ± 5.4% of the planned sessions. There were no adverse events.

Conclusions: In the present representative MS group, with 43% of patients showing signs of mild to moderate cognitive impairment, 24 weeks of supervised progressive aerobic exercise had no effect on cognitive performance.

[ActiveMSers]

What else could be going on here? Assuming this study was done accurately, and it really was HIIT, I have a theory to explain all the anecdotal evidence that HIIT is effective in influencing cognition. That could still be true, and still jive with this study. Here's why.

What if HIIT does not "improve" cognition, but only prevents worsening? That would explain why the study didn't show any cognitive improvement, and it would explain why many diligent exercisers report fewer cognitive issues. Aerobic exercise is known to prevent brain atrophy, but it doesn't build brain volume, or else professional athletes would have to have flexible skulls to manage their growing brains.

So my takeaway. Still exercise. Still do HIIT. But don't wait until you have cognitive challenges to start, thinking you can reverse it. Because based on this study, once cognitive issues set in, it may be hard to impossible to regain normal brain function.

[AMFADVENTURES]

Well, I suppose the tests they used may not have indicated an improvement in cognition and you might be right, as I recall (and I am prone to mis remembering) other studies indicated an increase in BDNF, Brain Derived Neurotropic Factor, which is considered necessary for neural cell growth, neurons which are notoriously slow anyway, but which may have been assumed merely based on the presence of BDNF. And as I recall, brain volume studies also correlated positively with Hiit, again assumed neural cell growth. I also seem to (mis?) remember a study which did show growth of the hypothalamus with HIIT though. Of course, I suppose neural cell growth doesn't necessarily have to correlate with cognition. Might be interesting to read the whole study.

It would be pretty unusual for studies like this, to show much of a difference between PWMS and people without MS and if such a difference did in fact appear, it would certainly necessatate further study to determine the reason why, wouldn't it?

Larry