Effects of acute stress on cognition in older versus younger adults

Biopsychosocial risk factors for subjective cognitive decline among older adults during the COVID-19 pandemic: a population-based study

OBJECTIVES

There have been concerns that the COVID-19 pandemic and the measures used to contain it impacted the cognitive health of older adults. We therefore examined the prevalence of subjective cognitive decline, and its associated risk factors and health consequencs, among dementia-free older adults 2 years into the pandemic in Switzerland.

STUDY DESIGN

Population-based cohort study.

METHODS

Prevalence of SCD was estimated using the cognitive complaint questionnaire administered to adults aged ≥65 years in June-September 2022 (Specchio-COVID19 cohort, N = 1414), and compared to prepandemic values from 2014 to 2018 (CoLaus|PsyCoLaus cohort, N = 1181). Associated risk factors and health consequences were assessed using logistic and/or linear regression.

RESULTS

Prevalence of SCD in 2022 (18.9% [95% CI, 16.2-21.9]) was comparable to prepandemic levels in 2014-2018 (19.5% [17.2-22.1]). Risk factors included established risks for dementia-namely health issues, health behaviours, and depressive symptoms. Self-reported post-COVID, perceived worsening of mental health since the start of the pandemic, less frequent social club attendance, and increased loneliness were also risk factors for SCD. In turn, SCD was associated with poorer objective cognitive performance, difficulty performing instrumental activities of daily living, greater risk of falls, and lower well-being at one-year follow-up.

CONCLUSIONS

While the overall prevalence of SCD in 2022 was comparable to prepandemic levels, we identified several pandemic-related risk factors for SCD, including perceived worsening of mental health and increased isolation since the start of the pandemic. These findings highlight the importance of mental health promotion strategies in reducing cognitive complaints and preventing cognitive decline.

Internet Use as a Moderator of the Relationship Between Personal Resources and Stress in Older Adults: Cross-Sectional Study

BACKGROUND

Internet use has dramatically increased worldwide, with over two-thirds of the world's population using it, including the older adult population. Technical resources such as internet use have been shown to influence psychological processes such as stress positively. Following the Conservation of Resources theory by Hobfoll, stress experience largely depends on individuals' personal resources and the changes in these resources. While personal resource loss has been shown to lead to stress, we know little regarding the role that technical resources may play on the relationship between personal resources and stress.

OBJECTIVE

This study aims to investigate the moderating effect of technical resources (internet use) on the relationship between personal resources and stress in younger and older adults.

METHODS

A total of 275 younger adults (aged 18 to 30 years) and 224 older adults (aged ≥65 years) indicated their levels of stress; change in personal resources (ie, cognitive, social, and self-efficacy resource loss and gain); and internet use. Variance analyses, multiple regression, and moderation analyses were performed to investigate the correlates of stress.

RESULTS

Results showed that older adults, despite experiencing higher levels of resource loss (questionnaire scores: 1.82 vs 1.54; P<.001) and less resource gain (questionnaire scores: 1.82 vs 2.31; P<.001), were less stressed than younger adults (questionnaire scores: 1.99 vs 2.47; P<.001). We observed that the relationship among resource loss, resource gain, and stress in older adults was moderated by their level of internet use (β=.09; P=.05). Specifically, older adults who used the internet more frequently were less stressed when they experienced high levels of both loss and gain compared to their counterparts who used internet the less in the same conditions. Furthermore, older adults with low resource gain and high resource loss expressed less stress when they used the internet more often compared to those with low internet use.

CONCLUSIONS

These findings highlight the importance of internet use in mitigating stress among older adults experiencing resource loss and gain, emphasizing the potential of digital interventions to promote mental health in this population.

Writing about a stressful experience improves semantic clustering of memory in men, not women

Writing about negative experiences can produce multiple benefits, including improvements in mental and emotional health. However, writing about negative experiences potentially be detrimental, as reliving and reexperiencing a negative memory can be painful. Although the emotional effects of writing about negative experiences are well established, the cognitive effects are less heavily explored, and no work to date has examined how writing about a stressful experience might influence episodic memory. We addressed this issue in the present study (N = 520) by having participants encode a list of 16 words that were organised around four semantic clusters, randomly assigning participants to write about an unresolved stressful experience (n = 263) or the events of the previous day (n = 257), and assessing their memory in a free recall task. Writing about a stressful experience did not influence overall memory performance; however, the stressful writing manipulation increased semantic clustering of information within memory for men, whereas the stressful writing manipulation did not influence semantic clustering of information within memory in women. Additionally, writing with more positive sentiment improved semantic clustering and reduced serial recall. These results provide evidence for unique sex differences in writing about stressful experiences and the role of sentiment in the effects of expressive writing.

Acute stress impacts reaction times in older but not in young adults in a flanker task

Acute psychosocial stress effects on inhibition have been investigated in young adults, but little is known about these effects in older adults. The present study investigated effects of the Trier Social Stress Test on cognitive inhibition (i.e., ability to ignore distracting information) using a cross-over (stress vs. control) design in healthy young (N = 50; 18-30 years; Mage = 23.06) versus older adults (N = 50; 65-84 years; Mage = 71.12). Cognitive inhibition was measured by a letter flanker task and psychophysiological measures (cortisol, heart rate, subjective stress) validated the stress induction. The results showed that while stress impaired overall accuracy across age groups and sessions, stress (vs. control) made older adults' faster in session 1 and slower in session 2. Given that session 2 effects were likely confounded by practice effects, these results suggest that acute psychosocial stress improved older adults' RTs on a novel flanker task but impaired RTs on a practiced flanker task. That is, the interaction between stress and learning effects might negatively affect response execution when testing older adults on flanker tasks. If confirmed by future research, these results might have important implications especially in settings where repeated cognitive testing is performed under acute stress.

Adult age differences in the psychophysiological response to acute stress

Age-related differences in the psychophysiology of the acute stress response are poorly understood given the limited number of studies and the high heterogeneity of findings. The present study contributes by investigating age differences in both the psychological and physiological responses to acute stress in a sample of healthy younger (N = 50; 18-30; M_age = 23.06; SD = 2.90) and older adults (N = 50; 65-84; M_age = 71.12; SD = 5.02). Specifically, the effects of psychosocial stress (i.e., age-adapted Trier Social Stress Test) were investigated at numerous timepoints throughout the stress response phases (i.e., baseline, anticipation, reactivity, recovery) on cortisol, heart rate, subjective stress, and anticipatory appraisal of the stressful situation. The study was conducted in a between-subject (younger vs. older) cross-over (stress vs. control) design. Results revealed age-related differences in both physiological and psychological variables: older adults had overall lower salivary cortisol levels in the stress and control conditions and lower stress-induced cortisol increase (i.e., AUCi). In addition, older adults' cortisol reactivity was delayed compared to younger adults. Older adults showed a lower heart rate response in the stress condition while no age differences were observed in the control condition. Finally, older adults reported less subjective stress and a less negative stress appraisal during the anticipation phase than younger adults, which could potentially explain lower physiological reactivity in this age group. Results are discussed in relation to the existing literature, potential underlying mechanisms, and future directions for the field.

IL-6 Enhances the Negative Impact of Cortisol on Cognition among Community-Dwelling Older People without Dementia

There is growing evidence that high basal cortisol levels and systemic inflammation independently contribute to cognitive decline among older people without dementia. The present cross-sectional study examined (a) the potential synergistic effect of cortisol levels and systemic inflammation on executive function and (b) whether this effect is more prominent among older people with mild cognitive impairment (MCI). A sub-sample of 99 patients with MCI and 84 older people without cognitive impairment (CNI) (aged 73.8 ± 7.0 years) were recruited from a large population-based cohort in Crete, Greece, and underwent comprehensive neuropsychiatric and neuropsychological evaluation and a single morning measurement of cortisol and IL-6 plasma levels. Using moderated regression models, we found that the relation between cortisol and executive function in the total sample was moderated by IL-6 levels (b = −0.994, p = 0.044) and diagnostic group separately (b = −0.632, p < 0.001). Moreover, the interaction between cortisol and IL-6 levels was significant only among persons with MCI (b = −0.562, p < 0.001). The synergistic effect of stress hormones and systemic inflammation on cognitive status appears to be stronger among older people who already display signs of cognitive decline. Targeting hypercortisolemia and inflammation may be a promising strategy toward improving the course of cognitive decline.

Acute psychosocial stress impairs intention initiation in young but not older adults

Acute psychosocial stress has been shown to impair memory and cognitive control in young adults. So far, only very little empirical research is available concerning possible adult age differences in acute stress effects on cognition in general and cognitive control in particular. Accordingly, the present study set out to test these effects in a controlled laboratory setting comparing performance in a prospective memory task requiring the deployment of proactive cognitive control to successfully implement intentions. Sixty-six young (19-34 years) and 57 older adults (60-82 years) were either exposed to an established psychosocial stress procedure (Trier Social Stress Test) or an active control condition. Stress responses were measured on a fine-grained level across the entire procedure using subjective and physiological stress markers. Results suggest that the stress induction was equally successful in both age groups. While stress impaired prospective memory ability in young adults, it did not affect performance in the older adults. In particular, young adults under acute stress were more likely to completely fail the initiation of the prospective memory task resulting in zero performance. The missing stress effect on prospective memory in older adults is in line with previous studies examining broader mood effects on PM and suggests the exciting possibility that increasing age may act as a resilience factor against deterioration of cognitive control in emotionally challenging situations. AUTHOR NOTES: We thank Florence Caccia, Marta Guidotti, Nikol Hiller, Nada Kojovic, Raphaëlle Martin-Casas and Clémence Voirin for assistance with data collection, Robert Miller for advice concerning the data analyses and Antje Petzold, Jana Strahler and Moritz Walser for their advice regarding study and manuscript preparation. Preparation of this manuscript was funded by a grant (KL2303/5-1) from the Deutsche Forschungsgemeinschaft (DFG) to MK and CK.

Does older adults' cognition particularly suffer from stress? A systematic review of acute stress effects on cognition in older age

This literature review provides the first comprehensive qualitative and quantitative systematic synthesis of acute laboratory stress effects on older adults' cognition by specifying the direction and magnitude of those effects both overall and for different cognitive processes separately. A systematic literature search was performed, and effect sizes estimated whenever possible. We found meta-analytical evidence that stress has negative effects on older adults' verbal fluency (g_adj = -0.53, 95 % CI [-2.70, 1.63]), null-to-negative effects on episodic memory (g_adj = -0.26, 95 % CI [-0.44, -0.08]), null effects on executive functions (g_adj = 0.07, 95 % CI [-0.31, 0.46]), and enhancing effects on working memory (g_adj = 0.16, 95 % CI [-0.01, 0.33]). Relating these findings to those in young adults, notable differences emerged for some cognitive functions, such as opposing effects on working memory between age groups. Our review further reveals that stress effects on older adults' memory retention, associative memory, prospective memory, interference control or cognitive flexibility are heavily understudied. We provide a conceptual and methodological framework for future studies in older adults.

A large-scale study of stress, emotions, and blood pressure in daily life using a digital platform

Exaggerated blood pressure (BP) reactivity is associated with the development of hypertension and cardiovascular disease. Stress, and, to a lesser extent, emotions are suggested to be linked to BP reactivity, but this theorizing lacks robust evidence beyond small laboratory or field studies with narrow participant demographics. Using an app-based research study and analyzing more than 330,000 daily responses from over 20,000 people, we show that momentary stress, conceptualized as the perception of demands relative to resources, is associated with greater BP and heart rate reactivity. High-arousal negative emotions are associated with increased physiologic reactivity whereas low-arousal positive emotions are associated with decreased reactivity. These data point to daily stress experiences as likely candidates for improving physical health.

Stress is often associated with pathophysiologic responses, like blood pressure (BP) reactivity, which when experienced repeatedly may be one pathway through which stress leads to poor physical health. Previous laboratory and field studies linking stress to physiological measures are limited by small samples, narrow demographics, and artificial stress manipulations, whereas large-scale studies often do not capture measures like BP reactivity in daily life. We examined perceived stress, emotions, heart rate, and BP during daily life using a 3-wk app-based study. We confirmed the validity of a smartphone-based optic sensor to measure BP and then analyzed data from more than 330,000 daily responses from over 20,000 people. Stress was conceptualized as the ratio of situational demands relative to individual resources to cope. We found that greater demands were associated with higher BP reactivity, but critically, the ratio of demands relative to resources improved prediction of BP changes. When demands were higher and resources were lower, there was higher BP reactivity. Additionally, older adults showed greater concordance between self-reported stress and physiologic responses than younger adults. We also observed that physiologic reactivity was associated with current emotional state, and both valence and arousal mattered. For example, BP increased with high-arousal negative emotions (e.g., anger) and decreased with low-arousal positive emotions (e.g., contentment). Taken together, this work underscores the potential for expanding stress science and public health data using handheld phones to reliably and validly measure physiologic responses linked to stress, emotion, and physical health.