A team of researchers led by Andrew Kemp, Associate Professor of Psychology at Swansea University, has identified that impairment in the vagus nerve, the most important nerve in the human body, may initiate a slow series of physiological changes that impairs mental skills.
Vagal function plays an important role in mental skills by helping to suppress irrelevant and interfering stimuli. Previous research had investigated the relationship between heart rate variability (HRV) – the natural variability between consecutive heart beats reflecting the inhibitory effects of the vagus nerve over the heart – and cognitive function. However, it was unclear how changes in the vagus nerve impact on mental skills over time.
The vagus nerve also plays an important regulatory role over many physiological systems responsible for maintaining homeostasis such as inflammatory processes and glucose regulation. Professor Kemp’s research shows that reduced vagal function increases insulin resistance – a feature of type II diabetes characterised by poor regulation of glucose in the body – leading to a thickening of the carotid arteries, which then adversely impacts on mental skills.
Professor Kemp (pictured) has been living and working in Brazil as an invited visiting Professor at the University of São Paulo. His study was based on a large sample of Brazilian civil servants aged 35-74, all of which were recruited for the Brazilian Longitudinal Study of Adult Health. Assessments included:
- 10-minute electrocardiogram (ECG) recordings collected while participants were at rest to obtain HRV.
- Blood samples collected after a 12-hour fast so that insulin resistance could be determined.
- Carotid intima-media thickness test to assess atherosclerosis.
- Trail making test (part B) to examine cognitive flexibility, attention and speed.
Professor Kemp, said: “The findings of this research demonstrate that the vagus nerve impacts on downstream processes, which over time, may lead to cognitive impairment. Our findings suggest that simple health behaviours known to benefit vagal function such as weight loss, smoking cessation, physical exercise and mediation may provide opportunities for short circuiting these adverse, downstream effects.”
The research, published in Biological Psychology, can be read here.
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