Importance of psychological factors in adrenocortical functioning and subjective memory complaints

El estrés ha sido considerado uno de los principales problemas de la sociedad actual, ya que se ha relacionado con diversas condiciones de salud mental y física, así como con enfermedades propias de la edad y problemas de memoria. Sin embargo, existen diferencias individuales en la forma en que las personas enfrentan situaciones estresantes. En este sentido, algunas personas, a pesar de estar expuestas a los mismos niveles de estrés, no desarrollan patologías, lo que sugiere que ciertos factores psicológicos podrían actuar como protectores de los efectos del estrés. La resiliencia, que engloba pensamientos positivos y optimistas, ha sido entendida como la capacidad de afrontar la adversidad y recuperarse de situaciones estresantes. Más importante aún, se ha propuesto como un factor importante asociado con una mejor salud y un envejecimiento exitoso. Entre los trastornos relacionados con la edad, se ha prestado mayor atención al deterioro cognitivo y la detección temprana de la demencia. La prioridad actual es estudiar qué factores podrían prevenir o retrasar el deterioro cognitivo. En este sentido, las Quejas Subjetivas de Memoria (QSM) a lo largo del tiempo, o el Deterioro Cognitivo Subjetivo (SCD), se han sugerido indistintamente como un proxy para la detección temprana de demencia en personas mayores. Sin embargo, estas QSM también aparecen en individuos jóvenes, lo que aumenta la necesidad de determinar qué factores podrían estar asociados con este fenómeno en las diferentes edades. Todo ello pone de relieve la importancia de estudiar cómo determinados factores psicológicos, especialmente los protectores, podrían estar relacionados con el estrés y las SMC a lo largo de la vida, pero especialmente en las personas mayores por ser una etapa de mayor vulnerabilidad tanto al estrés como a la pérdida de memoria. En esta tesis doctoral se abordan los dos principales temas de preocupación en las sociedades actuales, es decir, el estrés y la detección precoz de las demencias y cómo pueden afectarles diferentes factores psicológicos. Para ello, se han relacionado factores psicológicos de resiliencia (positividad, optimismo) y vulnerabilidad (pesimismo) con diferentes biomarcadores de estrés (saliva y cabello) y contextos (respuesta a un estresor y estrés crónico) en personas mayores sanas. En segundo lugar, la relación entre las QSM y diferentes factores de vulnerabilidad (ansiedad y depresión), factores protectores (resiliencia y positivismo), estrés (funcionamiento basal del eje hipotalámico pituitario suprarrenal [eje HPA]) y biomarcadores neurodegenerativos de la enfermedad de Alzheimer (EA) y Se han abordado las enfermedades cerebrovasculares (ECV). Este segundo objetivo general también se ha abordado en diferentes grupos de edad (es decir, jóvenes sanos, personas de mediana edad y mayores). En definitiva, esta tesis doctoral ayuda a clarificar el papel de algunos indicadores psicológicos y de estrés, con el fin de potenciar y fomentar futuras investigaciones e intervenciones enfocadas a la mejora de la salud y el envejecimiento saludable.Stress has been considered one of the main problems in today’s society, given that it has been related to several mental and physical health conditions, as well as age-related diseases and memory problems. However, there are individual differences in the way people face stressful situations. In this sense, some people, despite being exposed to the same levels of stress, do not develop pathologies, suggesting that certain psychological factors could act as protectors from the effects of stress. Resilience, which encompasses positive and optimistic thoughts, has been understood as the ability to face adversity and recover from stressful situations. More importantly, it has been proposed as an important factor associated with better health and successful aging. Among the age-related disorders, greater attention has been paid to cognitive decline and early dementia detection. The current priority is to study which factors could prevent or delay cognitive impairment. In this regard, Subjective Memory Complaints (SMCs) over time, or Subjective Cognitive Decline (SCD), have been indistinctly suggested as a proxy for early dementia detection in older people. However, these SMCs also appear in young individuals, increasing the need to determine which factors could be associated with this phenomenon at different ages. All of this highlights the importance of studying how certain psychological factors, especially protective factors, could be related to stress and SMCs across the lifespan, but especially in older people because it is a stage of greater vulnerability to both stress and memory decline. In this doctoral thesis, the two main issues of concern in today's societies are addressed, that is, stress and early detection of dementia and how different psychological factors can affect them. For this purpose, psychological factors of resilience (positivity, optimism) and vulnerability (pessimism) have been related to different stress biomarkers (saliva and hair) and contexts (response to a stressor and chronic stress) in healthy older people. Secondly, the relationship between SMCs and different vulnerability factors (anxiety and depression), protective factors (resilience and positivism), stress (basal functioning of the Hypothalamic Pituitary Adrenal axis [HPA axis]), and neurodegenerative biomarkers of Alzheimer’s disease (AD) and Cerebrovascular Disease (CVD) have been addressed. This second general objective has also been addressed in different age groups (i.e., healthy young, middle-aged, and older people). In sum, this doctoral thesis helps to clarify the role of some psychological and stress indicators, in order to enhance and encourage future research and interventions focused on improving health and healthy aging

Openness to experience and cognitive functioning and decline in older adults: The mediating role of cognitive reserve

Objective Openness to experience has been consistently associated with better cognitive functioning in older people, but its association with cognitive decline is less clear. Cognitive reserve has been proposed as a mechanism underlying this relationship, but previous studies have reported mixed findings, possibly due to the different ways of conceptualizing cognitive reserve. We aimed to analyze the potential mediating role of cognitive reserve in the association between openness and cognitive functioning and decline in healthy older people. Method In Wave 1 and at the four-year follow-up (Wave 2), 87 healthy older people (49.4% women; M age = 65.08, SD = 4.54) completed a neuropsychological battery to assess cognitive functioning and a questionnaire to assess cognitive reserve. Openness was measured with the NEO- Five-Factor Inventory. Mediation models were proposed to investigate the relationship between openness and cognitive function or decline through cognitive reserve or its change. Results Cognitive reserve mediated the openness-cognitive functioning association. Thus, individuals with higher openness showed greater cognitive reserve, and this greater cognitive reserve was associated with better cognitive functioning. Moreover, greater cognitive reserve at baseline also mediated the association between higher openness and slower cognitive decline. However, change in cognitive reserve did not mediate the association between openness and change in cognitive functioning. Conclusions Cognitive reserve is a mechanism underlying the association between openness and cognitive functioning and decline. These findings support the differential preservation hypothesis, suggesting that healthy older adults who engage in more cognitively stimulating activities would show less age-related cognitive decline

Hair cortisol and dehydroepiandrosterone and their associations with optimism and pessimism in older people

The cumulative negative effects of prolonged Hypothalamic-Pituitary-Adrenal axis (HPA axis) activation are associated with several age-related diseases. Some psychological traits such as optimism and pessimism have been shown to be related to both health and the stress response, although their relationship with the HPA axis is inconclusive. More stable HPA axis biomarkers, such as hair samples of cortisol (HC) and dehydroepiandrosterone (HDHEA), would help to clarify the association between these psychological traits and HPA axis functioning. The main aim of this study was to test the relationships between optimism and pessimism and chronic stress biomarkers measured in hair (HC and HDHEA). Additionally, a secondary objective was to explore sex differences in HC and HDHEA levels and their relationship with these psychological traits. We measured optimism, pessimism, and their combination (dispositional optimism) using the Life Orientation Test Revised (LOT-R) and chronic stress biomarkers (HC and HDHEA) in 119 healthy participants (46 men and 73 women) between 56 and 81 years old who belonged to a university program. Regression analyses controlling for perceived stress and BMI indicated that higher dispositional optimism was related to lower HC and HC:HDHEAratio (β = -0.256, p = .008 and β = -0.300, p = .002, respectively). More specifically, higher pessimism was related to higher HC (β = 0.235; p = .012) and HC:HDHEAratio (β = 0.240; p = .011), whereas higher optimism was associated with a lower HC:HDHEAratio(β = -0.205; p = .031). Moderation analyses showed no sex differences. To date, this is the first study to investigate the link between these traits and HC and HDHEA in older people. Our results confirm that positive and negative expectations about the future (i.e. optimism and pessimism) may play an important role in health due to their relationship with the HPA axis. They also strengthen the idea that the negative effects of pessimism have a greater weight than the protective effects of optimism in their relationship with HPA axis regulation

EEG markers and subjective memory complaints in young and older people

Subjective memory complaints (SMCs) have been related to subtle cognitive deficits and neural changes. In this study, we investigated whether EEG rhythms, usually altered in mild cognitive impairment and Alzheimer's disease, are also affected in SMCs compared to people without SMCs. Seventy-one older adults (55–74 years old) and 75 young people (18–34 years old) underwent 3 min of EEG recording in a resting-state condition with their eyes open (EO) and eyes closed (EC) and a comprehensive neuropsychological evaluation. The EEG measures included were power spectral delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (13–30 Hz), and EEG reactivity to EO. Compared to controls, older people with SMCs showed increased theta power and a loss of alpha reactivity to EO. Additionally, in older participants with SMCs, the theta power spectral was related to deficits in verbal memory. In contrast, we failed to find differences in the young people with SMCs, compared to the control group, in the power spectral or the EEG reactivity to EO. Our findings suggest that neurophysiological markers of brain dysfunction may identify cognitive changes even before they are observed on objective neuropsychological tests, at least in older people

Relació entre patrons d’activitat autònoma i el record d’estímuls emocionals en joves sans

Antecedents: estudis previs han destacat que la naturalesa emocional dels estímuls i el nivell d’activitat de determinades estructures cerebrals responsables de la regulació de l’activitat autònoma condicionen la codificació i record posterior. Així doncs, aquest estudi pilot té com a principal objectiu explorar la relació entre patrons d’activitat autònoma i el record de material emocional. Mètode: es va registrar la freqüència cardíaca de forma continua en un total de 27 homes i dones d’entre 18 i 29 anys d’edat mentre eren exposats a estímuls emocionals. Immediatament després, havien de recordar les imatges que havien vist. Es van identificar dos grups diferenciats en quant al patró d’activitat cardiovascular: un grup que va mostrar un canvi en la seua activitat autònoma en ser exposat a estímuls emocionals –grup Canvi–, i un grup que no va canviar durant l’exposició –grup No-Canvi–. Resultats: els nostres resultats van mostrar que el grup de Canvi van recordar un major nombre d’imatges emocionals –negatives i positives– que d’imatges neutres. A més, el grup Canvi va mostrar un pitjor record d’imatges negatives, comparat amb el seu propi rendiment en el record d’imatges positives i amb el record d’imatges negatives pel grup No-Canvi. Conclusions principals: els resultats d’aquest estudi recolzen les dades prèvies que han destacat la importància de l’activació autònoma en el procés d’aprenentatge i record de material emocional

Biomarkers of Alzheimer’s disease and cerebrovascular disease in relation to depressive symptomatology in individuals with subjective cognitive decline

Background: Subjective cognitive decline (SCD) has gained recent interest as a potential harbinger of neurodegenerative diseases such as Alzheimer’s disease (AD) and cerebrovascular disease (CVD). In addition, SCD can be related to depressive symptomatology. However, the association between AD and CVD biomarkers, depressive symptomatology, and SCD is still unclear. We investigated the association of AD and CVD biomarkers and depressive symptomatology with SCD in individuals with subjective memory complaints (SCD-memory group) and individuals with subjective concentration complaints (SCD-concentration group).// Methods: We recruited a population-based cohort of 217 individuals (all aged 70 years, 53% female, 119 SCD-memory individuals, 23 SCD-concentration individuals, 89 controls). AD and CVD were assessed through cerebrospinal fluid levels of the Aβ42/40 ratio and phosphorylated tau, and white matter signal abnormalities on magnetic resonance imaging, respectively. Associations between biomarkers, depressive symptomatology, and SCD were tested via logistic regression and correlation analyses.// Results: We found a significant association of depressive symptomatology with SCD-memory and SCD-concentration. Depressive symptomatology was not associated with AD and CVD biomarkers. Both the phosphorylated tau biomarker and depressive symptomatology predicted SCD-memory, and the Aβ42/40 ratio and depressive symptomatology predicted SCD-concentration.// Conclusions: The role of depressive symptomatology in SCD may differ depending on the stage within the spectrum of preclinical AD (as determined by amyloid-beta and tau positivity), and does not seem to reflect AD pathology. Our findings contribute to the emerging field of subclinical depressive symptomatology in SCD, and clarify the association of different types of subjective complaints with distinct syndromic and biomarker profiles

Subjective memory complaints in young people; their relationship with objective cognitive performance and the role of neuroticism

Perceptions of recurrent forgetfulness or episodes of distraction in daily life are referred to as subjective memory complaints (SMCs). Their nature has been extensively studied in older adults, but their significance and relationship with neurocognitive performance have not been fully addressed in younger adults. Some psychological traits have been suggested as possible moderators of the association between objective and subjective memory performance. The first aim of this study was to analyze the correspondence between the objective and subjective perception of memory failures in young people. Second, we studied whether the psychological trait of neuroticism could be influencing this relationship. To do this, we measured SMCs, different cognitive domains (episodic and working memory and executive functions), and neuroticism in 80 young men and women. Results showed that only immediate episodic memory was statistically related to SMCs. Interestingly, the negative relationships between objective and subjective memory performance only appeared in participants with higher neuroticism. Thus, memory complaints reported by young people could reflect poorer immediate episodic memory performance, whereas neuroticism would play a main role in the association between memory deficits and SMCs. This study provides data that can help to better understand SMCs in young people. Las percepciones de olvidos recurrentes o episodios de distracción en la vida diaria se denominan quejas subjetivas de memoria (QSM). Su naturaleza se ha estudiado ampliamente en adultos mayores, pero su importancia y relación con el rendimiento neurocognitivo no se han abordado por completo en adultos más jóvenes. Se han sugerido algunos rasgos psicológicos como posibles moderadores de la asociación entre el rendimiento de la memoria objetiva y subjetiva. El primer objetivo de este estudio fue analizar la correspondencia entre la percepción objetiva y subjetiva de los fallos de memoria en jóvenes. En segundo lugar, estudiamos si el rasgo psicológico del neuroticismo podría estar influyendo en esta relación. Para ello, medimos QSM, diferentes dominios cognitivos (memoria episódica y de trabajo y funciones ejecutivas) y neuroticismo en 80 hombres y mujeres jóvenes. Los resultados mostraron que solo la memoria episódica inmediata estaba estadísticamente relacionada con los QSM. Curiosamente, las relaciones negativas entre el rendimiento de la memoria objetiva y subjetiva solo aparecieron en participantes con mayor neuroticismo. Por lo tanto, las quejas de memoria reportadas por los jóvenes podrían reflejar un peor rendimiento de la memoria episódica inmediata, mientras que el neuroticismo jugaría un papel principal en la asociación entre los déficits de memoria y las QSM. Este estudio proporciona datos que pueden ayudar a comprender mejor las QSM en los jóvenes

Biomarkers of Alzheimer’s Disease and Cerebrovascular Disease in Relation to Depressive Symptomatology in Individuals With Subjective Cognitive Decline

Background :Subjective cognitive decline (SCD) has gained recent interest as a potential harbinger of neurodegenerative diseases such as Alzheimer’s disease (AD) and cerebrovascular disease (CVD). In addition, SCD can be related to depressive symptomatology. However, the association between AD and CVD biomarkers, depressive symptomatology, and SCD is still unclear. We investigated the association of AD and CVD biomarkers and depressive symptomatology with SCD in individuals with subjective memory complaints (SCD-memory group) and individuals with subjective concentration complaints (SCD-concentration group). Methods:We recruited a population-based cohort of 217 individuals (all aged 70 years, 53% female participants, 119 SCD-memory individuals, 23 SCD-concentration individuals, and 89 controls). AD and CVD were assessed through cerebrospinal fluid levels of the Aβ42/40 ratio and phosphorylated tau, and white matter signal abnormalities on magnetic resonance imaging, respectively. Associations between biomarkers, depressive symptomatology, and SCD were tested via logistic regression and correlation analyses. Results: We found a significant association between depressive symptomatology with SCD-memory and SCD-concentration. Depressive symptomatology was not associated with AD and CVD biomarkers. Both the phosphorylated tau biomarker and depressive symptomatology predicted SCD-memory, and the Aβ42/40 ratio and depressive symptomatology predicted SCD-concentration. Conclusions:The role of depressive symptomatology in SCD may differ depending on the stage within the spectrum of preclinical AD (as determined by amyloid-beta and tau positivity), and does not seem to reflect AD pathology. Our findings contribute to the emerging field of subclinical depressive symptomatology in SCD and clarify the association of different types of subjective complaints with distinct syndromic and biomarker profiles