Dual-Task Walking May Reveal Brain Aging Sooner

Harvard Medical School

Walking is a complex task most commonly done while performing other tasks, like talking, reading signs, or making decisions. After the age of 65, however, such “dual-tasking” worsens walking performance for many people and may even cause unsteadiness.

  • By MICHAEL CHMURA | Hebrew SeniorLife

A new study from Harvard Medical School and Hebrew SeniorLife published in Lancet Healthy Longevity aimed to clarify the relationships between age, dual-task gait, and cognitive function in middle age, defined as 40 to 64 years of age.

The study found that the ability to dual-task when walking starts to decline by the age of 55, up to a decade before old age, as traditionally defined by the threshold of 65 years.

This decline in the ability to walk and talk at the same time was found to be caused by changes in cognition and underlying brain function, not by changes in physical function.

“Our results suggest that in middle age, poor dual-task walking performance might be an indicator of accelerated brain aging or an otherwise presymptomatic neurodegenerative condition,” said first author Junhong Zhou, HMS instructor in medicine at Hebrew SeniorLife.

The paper stemmed from a collaboration between researchers at the Hinda and Arthur Marcus Institute for Aging Research at Hebrew SeniorLife and the Institut Guttmann in Barcelona, where the population-based Barcelona Brain Health Initiative (BBHI) is based. The principal investigators of the BBHI are David Batrés-Faz of the University of Barcelona and Alvaro Pascual-Leone, HMS professor of neurology at Hebrew SeniorLife.

For this research, 996 community-dwelling adults aged 40 to 64 who were participating in the BBHI study were recruited between May 5, 2018, and July 7, 2020.

Of these, 640 (342 men and 298 women) completed gait and cognitive assessments during the study period (an average of 24 days between the first and second visit) and were included in the analysis.

“We assessed a large number of individuals between the ages of 40 and 64 years. We observed that the ability to walk under normal, quiet conditions remained relatively stable across this age range. However, even in this relatively healthy cohort, when we asked participants to walk and perform a mental arithmetic task at the same time, we were able to observe subtle yet important changes in gait starting in the middle of the sixth decade of life,” said Zhou.

According to the investigators, a simple test of dual-task walking, which probes the brain’s ability to perform two tasks at the same time, can uncover early, age-related changes in brain function that may signify an increased risk of developing dementia later in life.

“As compared to walking quietly, walking under dual-task conditions adds stress to the motor control system because the two tasks, walking and mental arithmetic, for example, must compete for shared resources in the brain,” Zhou said.

“What we believe is that the ability to handle this stress and adequately maintain performance in both tasks is a critical brain function that tends to be diminished in older age. Our study is important because it has discovered that changes in this type of brain resilience occur much earlier than previously believed,” he said.

The authors added that it’s important to note that while they observed that dual-task walking tended to diminish with advancing age across the entire cohort, not everyone in the study fit this description.

“We observed a portion of participants over the age of 60 who performed the dual task test as well as participants aged 50 or even younger. This means that dual-task walking performance does not necessarily decline as we get older, and that some individuals appear more resistant to the effects of aging,” Zhou said.

“We hope our study will spur future research to discover lifestyle and other modifiable factors that support the maintenance of dual task performance into old age, as well as interventions that target these factors,” he added.

Authorship, funding, disclosures

Co-authors included Gabriele Cattaneo, Wanting Yu, On-Ye Lo, Natalia Gouskova, Selma Delgado-Gallén, Maria Redondo-Camós, Goretti España-Irla, Javier Solana-Sánchez, Josep Tormos, Lewis Lipsitz, and Brand Manor.

This research was supported by La Caixa Foundation (grant number LCF/PR/PR16/11110004), Institut Guttmann, and Fundació Abertis. Junhong Zhou and Brad Manor are supported by grants from the National Institute on Aging (R01 AG059089-01 and 1K01AG075180-01).

Adapted from a Hebrew SeniorLife news release.

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