How Are Tip-of-the-Tongue States Linked to Aerobic Fitness?

Higher fitness levels are associated with less language decline as we age.

Posted May 03, 2018

Diego Cervo/Shutterstock
Source: Diego Cervo/Shutterstock

We all know the frustrating feeling of having someone’s name, a title, or a descriptive term on the tip of your tongue but lacking the cognitive ability at that moment to say the word. These are aptly named "Tip-of-the-Tongue (TOT) States," and as we age, the frequency of TOT states and so-called "brain farts" tends to increase.

But there is good news: A new study has found that maintaining higher levels of aerobic fitness as we age is linked to a lower frequency of tip-of-the-tongue states in healthy older adults. The paper, “Higher Physical Fitness Levels Are Associated with Less Language Decline in Healthy Ageing,” was published April 30 in the journal Scientific Reports. This research was led by a team at the University of Birmingham in the UK in collaboration with researchers at the University of Agder in Norway, the University of Leuven in Belgium, and King's College London.

This study had two cohorts: 28 older men and women in their late 60s and 27 younger people in their early 20s. All participants were evaluated on a stationary bicycle to establish each person’s baseline cardio-respiratory aerobic fitness.

For the linguistic “tip-of-the-tongue” part of this study, participants were asked to perform a series of computerized “definition filling tasks” to measure TOT-state frequency. These language tests included common and ‘low frequency’ descriptive terms as well as identifying actors, musicians, politicians, and others who were famous enough to be considered household names. Oftentimes, when someone is in a tip-of-the-tongue state, he or she will blurt out, “I know that I know this person’s name!” When something is on the tip of your tongue, you have a strong conviction that the crystallized knowledge of this person, place, or thing is stored somewhere in your brain. It's like an itch that you are unable to scratch. On the flip side, when you know you don't know something, it doesn't trigger a TOT state.

In 1893, William James, one of the fathers of modern psychology, eloquently described what we universally acknowledge as "tip-of-the-tongue states."

“Suppose we try to recall a forgotten name. The state of our consciousness is peculiar. There is a gap therein; but no mere gap. It is a gap that is intensely active. . . beckoning us in a given direction, making us at moments tingle with the sense of our closeness and then letting us sink back without the longed-for term.”

Usually, when I experience a TOT state and forget someone's name, a few minutes or hours later I’ll be doing something mindless (taking a shower, jogging, driving) when the name pops into my head out of the blue. This mini “aha!” moment is always followed by an immediate sense of psychological relief. When a TOT state is resolved, it feels as if a nagging riddle that your mind was wrestling with below the surface has finally revealed itself in a 'graspable' realm of cognitive awareness.

As the authors of the recent TOT study report, in addition to showing, as expected, that the older adults tended to experience more TOT moments than the younger ones, "the data show a relationship between aerobic fitness and word finding abilities in [the] group of healthy older adults.” Lead author Katrien Segaert, of the University of Birmingham's School of Psychology, emphasizes that the association between higher aerobic fitness levels and fewer tip-of-the-tongue states has nothing to do with vocabulary size or permanently forgetting a word. It appears that TOT states are more linked to cognitive fluidity than an actual loss of crystallized knowledge or declarative/explicit memories.

"Older adults sometimes worry that tip-of-the-tongue states indicate serious memory problems but this is a misconception: tip-of-the-tongue states are not associated with memory loss," Segaert said in a statement. "In fact, older adults usually have a much larger vocabulary than young adults. Instead, tip-of-the-tongue states occur when the meaning of a word is available in our memory, but the sound form of the word can temporarily not be accessed."

What Is the Neuroscientific Explanation?

Segaert et al. speculate that there are a variety of possible reasons why higher physical fitness levels were associated with fewer TOT issues in healthy older adults. The authors write: “Previous research on healthy older adults has demonstrated that tip-of-the-tongue states are associated with grey matter atrophy in the left insula and functional activation changes in linguistic... as well as extra-linguistic brain networks...”

Countless studies have shown that aerobic exercise and cardio-respiratory fitness have neuroprotective benefits. Regular moderate-to-vigorous physical activity across the human lifespan stimulates neurogenesis and boosts gray matter volumes in both hemispheres of the cerebrum and cerebellum as well as in the hippocampus. Additionally, physical fitness is associated with better white matter integrity and myelination of the white matter tracts connecting various brain regions. 

Interestingly, a groundswell of recent research has put the cerebellum in the spotlight as playing a key role in language processing. Historically, the cerebellum (Latin for "little brain") was viewed simply as the seat of muscle coordination and balance. In the 20th century, most experts didn't believe that our cerebellar hemispheres played a role in cognition or language. However, in recent years, there is a growing body of evidence that corroborates Jeremy Schmahmann's "Dysmetria of Thought" (1998) hypothesis, which posits that the cerebellum coordinates our thoughts (and words) much the same way it coordinates our movements. 

A surprising hallmark of abnormalities in cerebellum structure or functional connectivity with cerebral brain regions is metalinguistic impairments. Notably, when Schmahmann, of Harvard Medical School, first identified Cerebellar Cognitive Affective Syndrome (CCAS) in the 1990s, one of the tell-tale clues that damage to certain regions of the cerebellum might be linked to cognition was the observation of language deficits such as agrammatism, aprodosia, and anomia in those with ataxia or dysmetria. For example, after the removal of a tumor from certain parts of the cerebellum in pediatric patients, Schmahmann et al. (2000) noticed a reduction in expressive language marked by difficulty finding words, linguistic latencies, and a lack of elaboration.

Wikipedia/Public Domain
Source: Wikipedia/Public Domain

In a 2010 paper, "The Cerebellum and Language: Historical Perspective and Review," Bruce Murdoch concludes, "It is now more widely accepted that the cerebellum, and in particular the right cerebellar hemisphere, participates in modulation of cognitive functioning, especially to those parts of the brain to which it is reciprocally connected." Along this same line, an April 2018 paper reported for the first time that Neanderthals had less gray matter volume in the right cerebellar hemisphere than early Homo sapiens. which may have created language-related deficits. (For more on this see,  "Bigger Cerebellum Size May Have Helped Early Humans Thrive.")

As another example, an August 2017 paper, "The Role of the Cerebellum in the Regulation of Language Functions," concludes: "This brain structure {the cerebellum] until recently associated chiefly with motor skills, visual-motor coordination and balance, proves to be significant also for cognitive functioning." The authors write, "With regard to language functions, studies show that the cerebellum determines verbal fluency (both semantic and formal) expressive and receptive grammar processing, the ability to identify and correct language mistakes, and writing skills.”

Wikipedia/Public Domain
Drawing of Purkinje cells (A) and granule cells (B) from pigeon cerebellum by Santiago Ramón y Cajal, 1899; Instituto Cajal, Madrid, Spain
Source: Wikipedia/Public Domain

In regard to physical exercise maintaining brain volume in the cerebellum as we age: Researchers have known for decades that robust physical activity counteracts Purkinje cell loss in the cerebellar hemispheres of lab rats. Larsen, Skalicky, and Viidik (2000) write, “We found that sedentary aged rats have 11% fewer Purkinje cells and 9% smaller Purkinje cell volumes than exercised aged rats, and that exercised aged rats have the same number of Purkinje cells as young rats. These findings indicate that the degree of age‐associated degenerative changes in parts of the central nervous system is dependent on earlier life style and health habits and may be prevented or delayed by physical exercise."

This body of research on cerebellar brain volume, physical activity, and language ability dovetails with the main takeaway of the recent University of Birmingham study on the link between higher physical fitness and lower incidence of tip-of-the-tongue states in older adults.

In their concluding statements, Sagaert et al. wrap things up on an inspiring note: "The present results suggest that higher aerobic fitness levels are associated with better word production skills in healthy older adults, and thus further support the promotion of increased physical activity for healthy ageing and optimal brain function across the life span. Future research could focus therefore on whether structural and functional activation changes in these brain regions underlie fitness-related differences in word finding abilities.”

If you need a fresh source of motivation to stay physically active, hopefully, the latest empirical evidence on TOT states presented herein has convinced you to add "word finding abilities" and "less language decline" to your list of reasons to exercise more and sit less.

References

K. Segaert, S. J. E. Lucas, C. V. Burley, P. Segaert, A. E. Milner, M. Ryan, L. Wheeldon. "Higher Physical Fitness Levels Are Associated with Less Language Decline in Healthy Ageing." Scientific Reports (Published online: April 30, 2018) DOI: 10.1038/s41598-018-24972-1

Takanori Kochiyama, Naomichi Ogihara, Hiroki C. Tanabe, Osamu Kondo, Hideki Amano, Kunihiro Hasegawa, Hiromasa Suzuki, Marcia S. Ponce de León, Christoph P. E. Zollikofer, Markus Bastir, Chris Stringer, Norihiro Sadato, and Takeru Akazawa. "Reconstructing the Neanderthal Brain Using Computational Anatomy." Scientific Reports (First published online: April 26, 2018) DOI: 10.1038/s41598-018-24331-0

Catarina Albergaria, N. Tatiana Silva, Dominique L. Pritchett, and Megan R. Carey. "Locomotor Activity Modulates Associative Learning in Mouse Cerebellum." Nature Neuroscience (Published online: April 16, 2018) DOI: 10.1038/s41593-018-0129-x

Anna Starowicz-Filip, Adrian Andrzej Chrobak, M. Moskała, R. M. Krzyżewski, Borys Kwinta, Stanislaw Kwiatkowski, Olga Milczarek, Anna Rajtar-Zembaty, and D. Przewoźnik. "The Role of the Cerebellum in the Regulation of Language Functions." Psychiatria Polska (2017) DOI: 10.12740/PP/68547

Neil Gordon. "Speech, Language, and the Cerebellum." International Journal of Language and Communication Disorders (1996) DOI: 10.3109/13682829609031327

Susan Ravizza. “Movement and Lexical Access: Do Noniconic Gestures Aid in Retrieval?" Psychonomic Bulletin & Review (2002) DOI: 10.3758/BF0319652

Jytte Overgaard Larsen, Monika Skalicky, and Andrus Viidik. "Does Long‐Term Physical Exercise Counteract Age‐Related Purkinje Cell Loss? A Stereological Study of Rat Cerebellum." Journal of Comparative Neurology (2000) DOI: 10.1002/1096-9861(20001211)428:2<213::AID-CNE2>3.0.CO;2-Q

Lisi Levisohn, Alice Cronin-Golomb, and Jeremy D. Schmahmann. "Neuropsychological Consequences of Cerebellar Tumour Resection in Children: Cerebellar Cognitive Affective Syndrome in a Paediatric Population." Brain (2000) DOI: 10.1093/brain/123.5.1041

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