Dietary and serum tyrosine, white matter microstructure and inter-individual variability in executive functions in overweight adults: relation to sex/gender and age

Tyrosine (tyr), the precursor of the neurotransmitter dopamine, is known to modulate cognitive functions including executive attention. Tyr supplementation is suggested to influence dopamine-modulated cognitive performance. However, results are inconclusive, regarding the presence or strength and also the direction of the association between tyr and cognitive function. This pre-registered cross-sectional analysis investigates whether diet-associated serum tyr relates to executive attention performance, and whether this relationship is moderated by differences in white matter microstructure. 59 healthy, overweight, young to middle-aged adults (20F, 28.3 ± 6.6 years, BMI: 27.3 ± 1.5 kg/m2) drawn from a longitudinal study reported dietary habits, donated blood and completed diffusion-weighted brain magnetic resonance imaging and the attention network test. Main analyses were performed using linear regressions and non-parametric voxel-wise inference testing.Confirmatory analyses did neither support an association between dietary and serum tyr nor a relationship between relative serum tyr/large neutral amino acids (LNAA) levels or white matter microstructure and executive attention performance. However, exploratory analyses revealed higher tyr intake, higher serum tyr and better executive attention performance in the male sex/gender group. In addition, older age was associated with higher dietary tyr intake and lower fractional anisotropy in a widespread cluster across the brain. Finally, a positive association between relative serum tyr/LNAA and executive attention performance was found in the male sex/gender group when accounting for age effects.Our analysis advances the field of dopamine-modulated cognitive functions by revealing sex/gender and age differences which might be diet-related. Longitudinal or intervention studies and larger sample sizes are needed to provide more reliable evidence for links between tyr and executive attention.

Are Adverse Childhood Experiences Associated with Worse Cognitive Function in Older Adults?

Objectives: Adverse childhood experiences (ACE) are associated with an increased risk for dementia, but this relationship and modifying factors are poorly understood. This study is the first to our knowledge to comprehensively examine the effect of ACE on specific cognitive functions and measures associated with greater risk and resiliency to cognitive decline in independent community-dwelling older adults. Methods: Verbal/nonverbal intelligence, verbal memory, visual memory, and executive attention were assessed. Self-report measures examined depression, self-efficacy, and subjective cognitive concerns (SCC). The ACE questionnaire measured childhood experiences of abuse, neglect, and household dysfunction. Results: Over 56% of older adults reported an adverse childhood event. ACE scores were negatively associated with income and years of education and positively associated with depressive symptoms and SCC. ACE scores were a significant predictor of intellectual function and executive attention; however, these relationships were no longer significant after adjusting for education. Follow-up analyses using the PROCESS macro revealed that relationships among higher ACE scores with intellectual function and executive attention were mediated by education. Conclusions: Greater childhood adversity may increase vulnerability for cognitive impairment by impacting early education, socioeconomic status, and mental health. These findings have clinical implications for enhancing levels of cognitive reserve and addressing modifiable risk factors to prevent or attenuate cognitive decline in older adults.

Fluid intelligence and the locus coeruleus–norepinephrine system

The last decade has seen significant progress identifying genetic and brain differences related to intelligence. However, there remain considerable gaps in our understanding of how cognitive mechanisms that underpin intelligence map onto various brain functions. In this article, we argue that the locus coeruleus–norepinephrine system is essential for understanding the biological basis of intelligence. We review evidence suggesting that the locus coeruleus–norepinephrine system plays a central role at all levels of brain function, from metabolic processes to the organization of large-scale brain networks. We connect this evidence with our executive attention view of working-memory capacity and fluid intelligence and present analyses on baseline pupil size, an indicator of locus coeruleus activity. Using a latent variable approach, our analyses showed that a common executive attention factor predicted baseline pupil size. Additionally, the executive attention function of disengagement––not maintenance––uniquely predicted baseline pupil size. These findings suggest that the ability to control attention may be important for understanding how cognitive mechanisms of fluid intelligence map onto the locus coeruleus–norepinephrine system. We discuss how further research is needed to better understand the relationships between fluid intelligence, the locus coeruleus–norepinephrine system, and functionally organized brain networks.

Videogame exposure positively associates with selective attention in a cross-sectional sample of young children

There is growing interest in how exposure to videogames is associated with young children’s development. While videogames may displace time from developmentally important activities and have been related to lower reading skills, work in older children and adolescents has suggested that experience with attention-demanding/fast-reaction games positively associates with attention and visuomotor skills. In the current study, we assessed 154 children aged 4–7 years (77 male; mean age 5.38) whose parents reported average daily weekday recreational videogame time, including information about which videogames were played. We investigated associations between videogame exposure and children’s sustained, selective, and executive attention skills. We found that videogame time was significantly positively associated only with selective attention. Longitudinal studies are needed to elucidate the directional association between time spent playing recreational videogames and attention skills.