Sharp Brains: Brain Fitness and Cognitive Health News

Neuroplasticity, Brain Fitness and Cognitive Health News


The more hours you sit per day, the smaller your medial temporal lobe (MTL) seems to become, brain scans show

—– In the study, both (A) Total medi­al tem­po­ral lobe (MTL) and (B) parahip­pocam­pal thick­ness cor­re­lat­ed inverse­ly with hours of sitting/day, con­trol­ling for age. Ref­er­ence: Sid­darth P et al (2018), Seden­tary behav­ior asso­ci­at­ed with reduced medi­al tem­po­ral lobe thick­ness in mid­dle-aged and old­er adults. PLOS ONE 13(4): e0195549.

Sit­ting is bad for your brain — not just your metab­o­lism or heart (UCLA release):

UCLA researchers recruit­ed 35 peo­ple ages 45 to 75 and asked about their phys­i­cal activ­i­ty lev­els and the aver­age num­ber of hours per day they spent sit­ting over the pre­vi­ous week. Each per­son had a high-res­o­lu­tion MRI scan, which pro­vides a detailed look at the medi­al tem­po­ral lobe, or MTL, a brain region involved in the for­ma­tion of new mem­o­ries.

The researchers found that seden­tary behav­ior is a sig­nif­i­cant pre­dic­tor of thin­ning of the MTL and that phys­i­cal activ­i­ty, even at high lev­els, is insuf­fi­cient to off­set the harm­ful effects of sit­ting for extend­ed periods…The researchers next hope to fol­low a group of peo­ple for a longer dura­tion to deter­mine if sit­ting caus­es the thin­ning and what role gen­der, race, and weight might play in brain health relat­ed to sit­ting.

MTL thin­ning can be a pre­cur­sor to cog­ni­tive decline and demen­tia in mid­dle-aged and old­er adults. Reduc­ing seden­tary behav­ior may be a pos­si­ble tar­get for inter­ven­tions designed to improve brain health in peo­ple at risk for Alzheimer’s dis­ease, researchers said.”

The Study:

Seden­tary behav­ior asso­ci­at­ed with reduced medi­al tem­po­ral lobe thick­ness in mid­dle-aged and old­er adults (PLOS One). From the abstract:

  • (Back­ground) Atro­phy of the medi­al tem­po­ral lobe (MTL) occurs with aging, result­ing in impaired episod­ic mem­o­ry. Aer­o­bic fit­ness is pos­i­tive­ly cor­re­lat­ed with total hip­pocam­pal vol­ume, a heav­i­ly stud­ied mem­o­ry-crit­i­cal region with­in the MTL. How­ev­er, research on asso­ci­a­tions between seden­tary behav­ior and MTL sub­re­gion integri­ty is lim­it­ed. Here we explore asso­ci­a­tions between thick­ness of the MTL and its sub­re­gions, phys­i­cal activ­i­ty, and seden­tary behav­ior.
  • (Meth­ods) We assessed 35 non-dement­ed mid­dle-aged and old­er adults (25 women, 10 men; 45–75 years) using the Inter­na­tion­al Phys­i­cal Activ­i­ty Ques­tion­naire for old­er adults, which quan­ti­fies phys­i­cal activ­i­ty lev­els in MET-equiv­a­lent units and asks about the aver­age num­ber of hours spent sit­ting per day. All par­tic­i­pants had high res­o­lu­tion MRI scans per­formed on a Siemens Alle­gra 3T MRI scan­ner, which allows for detailed inves­ti­ga­tion of the MTL.
  • (Results) Con­trol­ling for age, total MTL thick­ness cor­re­lat­ed inverse­ly with hours of sitting/day (r = ‑0.37, p = 0.03). In MTL sub­re­gion analy­sis, parahip­pocam­pal (r = ‑0.45, p = 0.007), entorhi­nal (r = ‑0.33, p = 0.05) cor­ti­cal and subicu­lum (r = ‑0.36, p = .04) thick­ness­es cor­re­lat­ed inverse­ly with hours of sitting/day. No sig­nif­i­cant cor­re­la­tions were observed between phys­i­cal activ­i­ty lev­els and MTL thick­ness. Though pre­lim­i­nary, our results sug­gest that more seden­tary non-dement­ed indi­vid­u­als have less MTL thick­ness. Future stud­ies should include lon­gi­tu­di­nal analy­ses and explore mech­a­nisms, as well as the effi­ca­cy of decreas­ing seden­tary behav­iors to reverse this asso­ci­a­tion.

The Study in Context:

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  1. Rob says:

    It s a com­mon mis­con­cep­tion that exer­cise can com­pen­sate for too much sit­ting. Even if you engage in the doc­tor-rec­om­mend­ed 150 min­utes of mod­er­ate to vig­or­ous activ­i­ty per week, you are still sub­ject to the neg­a­tive impact of too much sit­ting.

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