By Gretchen
Reynolds
May 15,
2018
Call them
tip-of-the-tongue moments: those times we can’t quite call up the name or word
that we know we know. These frustrating lapses are thought to be caused by a
brief disruption in the brain’s ability to access a word’s sounds. We haven’t
forgotten the word, and we know its meaning, but its formulation dances
teasingly just beyond our grasp. Though these mental glitches are common
throughout life, they become more frequent with age. Whether this is an
inevitable part of growing older or somehow lifestyle-dependent is unknown. But
because evidence already shows that physically fit older people have reduced
risks for a variety of cognitive deficits, researchers recently looked into the
relationship between aerobic fitness and word recall.
For the
study, whose results appeared last month in Scientific Reports, researchers at
the University of Birmingham tested the lungs and tongues, figuratively
speaking, of 28 older men and women at the school’s human-performance lab.
Volunteers were between 60 and 80 and healthy, with no clinical signs of
cognitive problems. Their aerobic capacities were measured by having them ride
a specialized stationary bicycle to exhaustion; fitness levels among the
subjects varied greatly. This group and a second set of volunteers in their 20s
then sat at computers as word definitions flashed on the screens, prompting
them to indicate whether they knew and could say the implied word. The
vocabulary tended to be obscure — “decanter,” for example — because words
rarely used are the hardest to summon quickly.
To no one’s
surprise, the young subjects experienced far fewer tip-of-the-tongue failures
than the seniors, even though they had smaller vocabularies over all, according
to other tests. Within the older group, the inability to identify and say the
right words was strongly linked to fitness. The more fit someone was, the less
likely he or she was to go through a “what’s that word again?” moment of mental
choking.
As an
observational investigation, a one-time snapshot of human capabilities, the
study cannot prove that greater fitness is what causes older brains to maintain
better processing skills; it can only suggest a correlation. Also, exercise
habits were not considered; aerobic fitness, which depends to some degree on
genetics, was the variable measured. Nor did the study look more broadly into
how fitness might interact with language processing as a person ages.
Nonetheless, “fitness has widespread effects on the brain,” says Katrien Segaert,
a psychologist at the University of Birmingham who led the study. The areas
affected include the frontal and temporal cortices, which are involved in
language processing.
