Research Spotlights: July 2018

research spotlight

Socioeconomic status is related to adult brain anatomy and organization

It has long been understood that socioeconomic status (SES) is related to brain structure and health in developing children and the older population, but a recent NIA-funded study suggests that this also applies to middle-aged adults.

Participants aged 20–89 years were recruited to examine the relationship between SES and brain organization and structure. SES was determined by educational attainment and either current or preretirement occupational socioeconomic index. Brain functional network organization was measured by resting-state functional correlations (RSFC), and MRI scans were used to measure gray matter thickness to assess age-related brain decline.

Results indicate SES moderates age-related differences in functional network organization. Throughout middle age (35–64 y), lower SES adults display reduced segregation in RSFC and lower mean cortical thickness. Across both measures, early middle-aged adults (35–49 y) with lower SES were comparable to late middle-aged adults (50–64 y) with higher SES. The relationship between SES and brain measures was still present after controlling for demographics, physical and mental health, and cognitive ability. Controlling for childhood SES also did not affect the relationship between current SES and functional network organization. These results suggest that middle-aged adults of low SES may have earlier signs of brain aging, but the cross-sectional nature of this research limits its conclusions.

Chan MY, Na J, Agres PF, Savalia NK, Park DC, Wig GS. 2018. Socioeconomic status moderates age-related differences in the brain’s functional network organization and anatomy across the adult lifespan. Proc Natl Acad Sci 115(22): E5144-E5153.

Opioids and non-opioid analgesics affect different types of stress

Mu-opioids and non-opioid analgesics appear to differentially affect the psychological and physiological components of psychosocial stress, according to a recent study funded by NIDA, NIGMS, and NIMH.

In a between-subject design, healthy young adults (18–40 y) were randomly assigned to receive either 2 or 4 mg of hydromorphone (mu-opioid analgesic), 1000 mg of acetaminophen (non-opioid analgesic), or placebo and were tested in the Trier Social Stress Test (TSST) and a non-stressful control task (NSCT). Physiological responses to stress included heart rate, blood pressure, salivary cortisol and pupillometry, and psychological measures included subjective reports of mood and stress.

TSST successfully increased all measures of physiological stress and increased anxiety and negative mood compared to the control task. Hydromorphone (4 mg) dose dependently decreased cortisol stress response, but acetaminophen did not. Both hydromorphone and acetaminophen reduced ratings of how challenging participants found the task. This suggests acetaminophen, the non-opioid analgesic, affects psychological responses to stress, not physiological, whereas hydromorphone affects both. Only the mu-opioid system was involved with physiological stress responses in humans, which builds upon similar results in preclinical studies. The results here contribute a greater understanding of the role of opioid and non-opioid systems in the complex physiological and psychological responses to social stress.

Bershad AK, Miller MA, Norman GJ, de Wit H. 2018. Effects of opioid- and non-opioid analgesics on responses to psychosocial stress in humans. Horm Behav 102:41-47.

Sensory impairments predict future health in aging adults

Multisensory loss in older adults is common and is related to poor health, but past research focused mostly on single impairments or dual sensory impairments. A recent report funded by NIA and NIAID suggests when considering impairments in all five senses, future health and mortality can be predicted.

This prospective study examined how global sensory impairment (GSI) predicts future health outcomes. GSI measures the underlying processes common to sensory dysfunction in all five senses: hearing, vision, smell, touch, and taste and is calculated from dysfunction measures across all senses. Baseline in-home interviews and 5-year follow up assessments of older adults (57–85 y) were conducted.  Sensory function of all five senses was assessed along with gait speed, activity, disability, cognition, overall health, and mortality.

At baseline, participants with worse GSI scores were slower and had impairments in activities of daily living. At follow up, these individuals had deficits in all measured areas: individuals had slower walking speeds, more disabilities, were less active, had worse cognitive function, poor overall health, or had died. GSI considers deterioration of all senses and suggests underlying mechanisms such as neurophysiological decline or decreased sensory input due to peripheral loss are contributing factors. Multiple sensory deficits may serve as a biomarker for identifying high risk older adults at risk of poor health outcomes.

Pinto JM, Wroblewski KE, Huisingh-Scheetz M, Correia C, Lopez KJ, Chen RC, Kern DW, Schumm PL, Dale W, McClintock MK. 2017. Global Sensory Impairment Predicts Morbidity and Mortality in Older U.S. Adults. J Am Geriatr Soc. 65(12):2587-2595.