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Reducing the risk of dementia can halt the worldwide increase of affected people. The multifactorial and heterogeneous nature of late-onset dementia, including Alzheimer's disease (AD), indicates a potential impact of multidomain lifestyle interventions on risk reduction. The positive results of the landmark multidomain Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) support such an approach. The World-Wide FINGERS (WW-FINGERS), launched in 2017 and including over 25 countries, is the first global network of multidomain lifestyle intervention trials for dementia risk reduction and prevention. WW-FINGERS aims to adapt, test, and optimize the FINGER model to reduce risk across the spectrum of cognitive decline-from at-risk asymptomatic states to early symptomatic stages-in different geographical, cultural, and economic settings. WW-FINGERS aims to harmonize and adapt multidomain interventions across various countries and settings, to facilitate data sharing and analysis across studies, and to promote international joint initiatives to identify globally implementable and effective preventive strategies.
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Enfermedad de Alzheimer/prevención & control , Demencia/prevención & control , Terapia por Ejercicio , Estilo de Vida , Ensayos Clínicos como Asunto , Cognición/fisiología , Humanos , Proyectos de Investigación , Conducta de Reducción del RiesgoRESUMEN
BACKGROUND: The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) showed cognitive benefits from a multidomain lifestyle intervention in at-risk older people. The LipiDiDiet trial highlighted benefits of medical food in prodromal Alzheimer's disease (AD). However, the feasibility and impact of multimodal interventions combining lifestyle with medical food in prodromal AD is unclear. METHODS: MIND-ADmini was a 6-month multinational (Sweden, Finland, Germany, France) proof-of-concept randomized controlled trial (RCT). Participants were 60-85 years old, had prodromal AD (International Working Group-1 criteria), and vascular/lifestyle risk factors. The parallel-group RCT had three arms: multimodal lifestyle intervention (nutritional guidance, exercise, cognitive training, vascular/metabolic risk management and social stimulation); multimodal lifestyle intervention + medical food (Fortasyn Connect); and regular health advice/care (control). Participants were randomized 1:1:1 (computer-generated allocation at each site). Outcome evaluators were blinded to randomization. Primary outcome was feasibility of the multimodal intervention, evaluated by recruitment rate during a 6-month recruitment phase, overall adherence in each intervention arm, and 6-month retention rate. Successful adherence was pre-specified as attending ≥ 40% of sessions/domain in ≥ 2/4 domains (lifestyle intervention), and consuming ≥ 60% of the medical food (lifestyle intervention + medical food). The secondary outcomes included adherence/participation to each intervention component and overall adherence to healthy lifestyle changes, measured using a composite score for healthy lifestyle. Cognitive assessments were included as exploratory outcomes, e.g. Clinical Dementia Rating scale. RESULTS: During September 2017-May 2019, 93 individuals were randomized (32 lifestyle intervention, 31 lifestyle + medical food, and 30 control group). Overall recruitment rate was 76.2% (64.8% during the first 6 months). Overall 6-month retention rate was 91.4% (lifestyle intervention 87.5%; lifestyle + medical food 90.3%; control 96.7%). Domain-specific adherence in the lifestyle intervention group was 71.9% to cognitive training, 78.1% exercise, 68.8% nutritional guidance, and 81.3% vascular risk management; and in the lifestyle + medical food group, 90.3% to cognitive training, 87.1% exercise, 80.7% nutritional guidance, 87.1% vascular risk management, and 87.1% medical food. Compared with control, both intervention arms showed healthy diet improvements (ßLifestyle×Time = 1.11, P = 0.038; ßLifestyle+medical food×Time = 1.43, P = 0.007); the lifestyle + medical food group also showed vascular risk reduction (P = 0.043) and less cognitive-functional decline (P < 0.05, exploratory analysis). There were 5 serious adverse events (control group: 1; lifestyle intervention: 3; lifestyle + medical food: 1) unrelated to interventions. CONCLUSIONS: The multidomain lifestyle intervention, alone or combined with medical food, had good feasibility and adherence in prodromal AD. Longer-term cognitive and other health benefits should be further investigated in a larger-scale trial. TRIAL REGISTRATION: ClinicalTrials.gov NCT03249688.
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Enfermedad de Alzheimer , Estilo de Vida , Humanos , Enfermedad de Alzheimer/terapia , Enfermedad de Alzheimer/psicología , Femenino , Masculino , Anciano , Persona de Mediana Edad , Anciano de 80 o más Años , Síntomas Prodrómicos , Terapia Combinada/métodos , Ejercicio Físico/fisiología , Disfunción Cognitiva/terapia , Disfunción Cognitiva/prevención & controlRESUMEN
Background: Allostatic load (AL) is defined as the cumulative dysregulation of neuroendocrine, immunological, metabolic, and cardiovascular systems that increases the susceptibility to stress-related health problems. Several dementia and Alzheimer's disease (AD) risk factors have been identified, yet little is known about the role of AL and its associations with AD biomarkers (e.g., beta-amyloid (Aß) or tau) and cognitive function among memory clinic patients. Hence, this study aims to assess the association between AL and AD biomarkers, cognitive performance, and cognitive decline after 3-years of follow-up. Methods: Data from 188 memory clinic patients were derived from the Cortisol and Stress in AD (Co-STAR) study in Sweden. Participants underwent baseline assessments including blood tests for AL measures (including cortisol, thyroid stimulating hormone, cobalamin, homocysteine, leukocytes, glycated hemoglobin, albumin, high-density and low-density lipoprotein cholesterol, triglycerides, and creatinine), cerebrospinal fluid (CSF) sampling for AD biomarkers and neuropsychological tests including five cognitive domains. Linear regressions were conducted, adjusting for age, sex, and education. Results: Higher AL was associated with lower CSF Aß1-42 levels (ß = -0.175, p = 0.025), reflecting higher brain levels of Aß1-42. Stratified analyses suggested a significant association among women but not men, although the AL-sex interaction was not statistically significant. AL was not significantly associated with T-tau level (ß = -0.030, p = 0.682) and P-tau level (ß = 0.091, p = 0.980). There were no significant associations between AL and cognition or cognitive decline after 3 years. Conclusion: This study showed that higher AL was associated with increased brain amyloid accumulation. This suggests that AL may play a role in AD/dementia pathophysiology. Potential sex-related differences should be assessed in further larger studies.
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Background: The emergence of COVID-19 was rapidly followed by infection and the deaths of millions of people across the globe. With much of the research and scientific advancement rightly focused on reducing the burden of severe and critical acute COVID-19 infection, the long-term effects endured by those who survived the acute infection has been previously overlooked. Now, an appreciation for the post-COVID-19 condition, including its neurological manifestations, is growing, although there remain many unknowns regarding the etiology and risk factors of the condition, as well as how to effectively diagnose and treat it. Methods: Here, drawing upon the experiences and expertise of the clinicians and academics of the European working group on COVID-19, we have reviewed the current literature to provide a comprehensive overview of the neurological sequalae of the post-COVID-19 condition. Results: In this review, we provide a summary of the neurological symptoms associated with the post-COVID-19 condition, before discussing the possible mechanisms which may underly and manifest these symptoms. Following this, we explore the risk factors for developing neurological symptoms as a result of COVID-19 and the post-COVID-19 condition, as well as how COVID-19 infection may itself be a risk factor for the development of neurological disease in the future. Lastly, we evaluate how the post-COVID condition could be accurately diagnosed and effectively treated, including examples of the current guidelines, clinical outcomes, and tools that have been developed to aid in this process, as well as addressing the protection provided by COVID-19 vaccines against the post-COVID-19 condition. Conclusions: Overall, this review provides a comprehensive overview of the neurological sequalae of the post-COVID-19 condition. Impact statement With our understanding of the neurological complications of the post-COVID-19 condition currently lacking sufficient depth, this review aimed at highlighting the current knowns and unknowns of the post-COVID-19 condition. In this review, we draw upon the experiences and expertise of the clinicians and academics of the European working group on COVID-19, as well as explore the current published literature, to evaluate a range of topics associated with the neurological complications of the post-COVID-19 condition. As a result, we have provided a comprehensive review of the topic. The European Working Group on SARS-CoV-2 Many essential questions surrounding COVID-19 remain unanswered, including its neurological complications and associated sequalae. In this review, we aim at identifying the current gaps in our understanding of post-COVID-19 neurological sequalae and suggest how future studies should be undertaken to fill these gaps. This review will draw upon the current biological and mechanistic understanding of COVID-19 and post-COVID-19 complications to discuss the clinically relevant aspects associated with the neurological manifestations of post-COVID-19 syndrome. From our discussions, the following questions were considered highly relevant for contemplation.
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COVID-19 , Enfermedades del Sistema Nervioso , Humanos , COVID-19/complicaciones , SARS-CoV-2 , Vacunas contra la COVID-19 , Síndrome Post Agudo de COVID-19 , Imagen por Resonancia Magnética , Encéfalo , Enfermedades del Sistema Nervioso/epidemiología , Enfermedades del Sistema Nervioso/etiologíaRESUMEN
Introduction: The often-cited mechanism linking brain-derived neurotrophic factor (BDNF) to cognitive health has received limited experimental study. There is evidence that cognitive training, physical exercise, and mindfulness meditation may improve cognition. Here, we investigated whether improvements in cognition after these three types of structured interventions are facilitated by increases in BDNF. Methods: A total of 144 heathy older adults completed a 5-week intervention involving working memory/cognitive training, physical exercise, mindfulness meditation, or an active control condition. Serum BDNF levels and Digit Symbol Test (DST) performance were measured pre- and post-intervention. Results: Linear mixed models suggested that only the cognitive training group demonstrated augmentation of BDNF and DST performance relative to the control condition. Path analysis revealed that changes in BDNF mediate intervention-related improvement in task performance. Regression analyses showed that, across all intervention conditions, increased BDNF levels were associated with increased DST scores. Discussion: This study appears to be the first to suggest that BDNF helps mediate improvements in cognition after working memory training in healthy older adults. Highlights: Older adults were randomized to physical activity, mindfulness, cognitive training (computerized cognitive training (CCT), or control.CCT, but no other condition, led to increased serum brain-derived neurotrophic factor (BDNF) levels.CCT led to improvement on the untrained Digit Symbol Test (DST) of speed/working memory.Path analysis: increases in BDNF mediate intervention-related improvement on DST.Increases in BDNF associated with improved DST across all experimental groups.
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The first WHO guidelines for risk reduction of cognitive decline and dementia marked an important milestone in the field of dementia prevention. In this paper, we discuss the evidence reviewed as part of the guidelines development and present the main themes emerged from its synthesis, to inform future research and policies on dementia risk reduction. The role of intervention effect-size; the mismatch between observational and intervention-based evidence; the heterogeneity of evidence among intervention trials; the importance of intervention duration; the role of timing of exposure to a certain risk factor and interventions; the relationship between intervention intensity and response; the link between individual risk factors and specific dementia pathologies; and the need for tailored interventions emerged as the main themes. The interaction and clustering of individual risk factors, including genetics, was identified as the overarching theme. The evidence collected indicates that multidomain approaches targeting simultaneously multiple risk factors and tailored at both individual and population level, are likely to be most effective and feasible in dementia risk reduction. The current status of multidomain intervention trials aimed to cognitive impairment/dementia prevention was also briefly reviewed. Primary results were presented focusing on methodological differences and the potential of design harmonization for improving evidence quality. Since multidomain intervention trials address a condition with slow clinical manifestation-like dementia-in a relatively short time frame, the need for surrogate outcomes was also discussed, with a specific focus on the potential utility of dementia risk scores. Finally, we considered how multidomain intervention could be most effectively implemented in a public health context and the implications world-wide for other non-communicable diseases targeting common risk factors, taking into account the limited evidence in low-middle income countries. In conclusion, the evidence from the first WHO guidelines for risk reduction of cognitive decline and dementia indicated that "one size does not fit all," and multidomain approaches adaptable to different populations and individuals are likely to be the most effective. Harmonization in trial design, the use of appropriate outcome measures, and sustainability in large at-risk populations in the context of other chronic disorders also emerged as key elements.
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Previous studies have indicated that an active lifestyle is associated with better brain health and a longer life, compared to a more sedentary lifestyle. These studies, both on human and animal subjects, have typically focused on a single activity, usually physical exercise, but other activities have received an increasing interest. One proposed mechanism is that physical exercise increases levels of brain-derived neurotrophic factor (BDNF) in the brain. For the first time, the long-term effects on serum BDNF levels were compared in persons who engaged in either physical exercise training, cognitive training, or mindfulness practice during 5 weeks, and compared with an active control group. Two cohorts of healthy older individuals, one from the Boston area in the US and one from the Växjö area in Sweden, participated. A total of 146 participants were randomly assigned to one of the four groups. All interventions were structurally similar, using interactive, computer-based software that directed participants to carry out specified activities for 35 minutes/day, 5 days per week for 5 weeks. Blood samples were obtained at baseline and soon after the completion of the 5-week long intervention program, and serum BDNF levels were measured using a commercially available ELISA. Only the group that underwent cognitive training increased their serum BDNF levels after 5 weeks of training (F1,74â=â4.22, pâ=â0.044, partial η2â=â0.054), corresponding to an average 10% increase. These results strongly suggest that cognitive training can exert beneficial effects on brain health in an older adult population.
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Factor Neurotrófico Derivado del Encéfalo/sangre , Cognición/fisiología , Ejercicio Físico/psicología , Envejecimiento Saludable , Aprendizaje/fisiología , Atención Plena/métodos , Anciano , Correlación de Datos , Femenino , Envejecimiento Saludable/fisiología , Envejecimiento Saludable/psicología , Estilo de Vida Saludable , Humanos , Masculino , Pruebas Neuropsicológicas , Evaluación de Resultado en la Atención de SaludRESUMEN
INTRODUCTION: Increased physical exercise is linked to enhanced brain health and reduced dementia risk. Exercise intervention studies usually are conducted at facilities in groups under trainer supervision. To improve scalability, accessibility, and engagement, programs may need to be structured such that individuals can execute and adjust routines in their own homes. METHODS: One hundred eighty-three healthy older adults from two sites (the United States and Sweden) were screened. One hundred fifty-six subjects (mean age 73.2), randomly assigned to one of four interventions (PACE-Yourself physical exercise program, mindfulness meditation, or Cogmed® adaptive or nonadaptive computerized working memory training) began the study. All interventions were structurally similar: occurring in subjects' homes using interactive, web-based software, over five weeks, â¼175 minutes/week. In the PACE-Yourself program, video segments presented aerobic exercises at different pace and intensity (P&I). The program paused frequently, allowing subjects to indicate whether P&I was "too easy," "too hard," or "somewhat hard." P&I of the subsequent exercise set was adjusted, allowing subjects to exercise at a perceived exertion level of "somewhat hard." Program completion was defined as finishing ≥60% of sessions. RESULTS: A high percentage of participants in all groups completed the program, although the number (86%) was slightly lower in the PACE-Yourself group than the other three. Excluding dropouts, the PACE-Yourself group had a lower adherence rate of 93%, compared with the other three (â¼98%). Over the five weeks, PACE-Yourself participants increased exercising at the highest intensity level, consistent with augmented aerobic activity over time. The number of exercise sessions completed predicted the postintervention versus preintervention increase in self-reported level of physical activity. DISCUSSION: This study supports the feasibility of a home-based, subject-controlled, exercise program in which P&I is regulated via real-time participant feedback, which may promote self-efficacy. Further study is needed to determine if similar results are found over longer periods and in more diverse populations.
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BACKGROUND: Developing effective interventions to attenuate age-related cognitive decline and prevent or delay the onset of dementia are major public health goals. Computerized cognitive training (CCT) has been marketed increasingly to older adults, but its efficacy remains unclear. Working memory (WM), a key determinant of higher order cognitive abilities, is susceptible to age-related decline and a relevant target for CCT in elders. OBJECTIVE: To evaluate the efficacy of CCT focused on WM compared to an active control condition in healthy older adults. METHODS: Eighty-two cognitively normal adults from two sites (USA and Sweden) were randomly assigned to Cogmed Adaptive or Non-Adaptive (active control) CCT groups. Training was performed in participants' homes, five days per week over five weeks. Changes in the performance of the Cogmed trained tasks, and in five neuropsychological tests (Trail Making Test Part A and Part B, Digit Symbol, Controlled Oral Word Association Test and Semantic Fluency) were used as outcome measures. RESULTS: The groups were comparable at baseline. The Adaptive group showed robust gains in the trained tasks, and there was a time-by-group interaction for the Digit Symbol test, with significant improvement only after Adaptive training. In addition, the magnitude of the intervention effect was similar at both sites. CONCLUSION: Home-based CCT Adaptive WM training appears more effective than Non-Adaptive training in older adults from different cultural backgrounds. We present evidence of improvement in trained tasks and on a demanding untrained task dependent upon WM and processing speed. The benefits over the active control group suggest that the Adaptive CCT gains were linked to providing a continuously challenging level of WM difficulty.
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Memoria a Corto Plazo , Terapia Asistida por Computador , Anciano , Anciano de 80 o más Años , Envejecimiento Cognitivo , Femenino , Humanos , Masculino , Pruebas Neuropsicológicas , Autocuidado/métodos , Método Simple Ciego , Terapia Asistida por Computador/métodos , Resultado del TratamientoRESUMEN
OBJECTIVE: To investigate the associations between midlife work-related stress and mild cognitive impairment (MCI), dementia, and Alzheimer's disease later in life, in a large representative population. METHOD: Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study participants were randomly selected from independent population-based surveys (mean age 50 years). A random sample of 2,000 individuals was invited for two reexaminations including cognitive tests (at mean age 71 and mean age 78), and 1,511 subjects participated in at least one reexamination (mean follow-up 28.5 years). Work-related stress was measured using two questions on work demands that were administered in midlife. Analyses adjusted for important confounders. RESULTS: Higher levels of midlife work-related stress were associated with higher risk of MCI (odds ratio [OR], 1.38; 95% confidence interval [CI], 1.08-1.76), dementia (OR, 1.53; CI, 1.13-2.07), and Alzheimer's disease (OR, 1.55; CI, 1.19-2.36) at the first follow-up among the CAIDE participants. Results remained significant after adjusting for several possible confounders. Work-related stress was not associated with MCI and dementia during the extended follow-up. DISCUSSION: Midlife work-related stress increases the risk for MCI, dementia, and Alzheimer's disease in later life. The association was not seen after the extended follow-up possibly reflecting selective survival/participation, heterogeneity in dementia among the oldest old, and a critical time window for the effects of midlife stress.
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Enfermedad de Alzheimer/etiología , Enfermedad de Alzheimer/psicología , Disfunción Cognitiva/etiología , Demencia/etiología , Estrés Psicológico/complicaciones , Estrés Psicológico/psicología , Carga de Trabajo/psicología , Anciano , Disfunción Cognitiva/psicología , Demencia/psicología , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas/estadística & datos numéricos , Psicometría , Riesgo , Estadística como Asunto , Suecia , Carga de Trabajo/estadística & datos numéricosRESUMEN
Brain-derived neurotrophic factor (BDNF) has a central role in brain plasticity by mediating changes in cortical thickness and synaptic density in response to physical activity and environmental enrichment. Previous studies suggest that physical exercise can augment BDNF levels, both in serum and the brain, but no other study has examined how different types of activities compare with physical exercise in their ability to affect BDNF levels. By using a balanced cross over experimental design, we exposed nineteen healthy older adults to 35-minute sessions of physical exercise, cognitive training, and mindfulness practice, and compared the resulting changes in mature BDNF levels between the three activities. We show that a single bout of physical exercise has significantly larger impact on serum BDNF levels than either cognitive training or mindfulness practice in the same persons. This is the first study on immediate BDNF effects of physical activity in older healthy humans and also the first study to demonstrate an association between serum BDNF responsivity to acute physical exercise and working memory function. We conclude that the BDNF increase we found after physical exercise more probably has a peripheral than a central origin, but that the association between post-intervention BDNF levels and cognitive function could have implications for BDNF responsivity in serum as a potential marker of cognitive health.
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Factor Neurotrófico Derivado del Encéfalo/sangre , Encéfalo/metabolismo , Ejercicio Físico/fisiología , Envejecimiento Saludable/fisiología , Memoria a Corto Plazo/fisiología , Atención Plena/métodos , Anciano , Anciano de 80 o más Años , Análisis de Varianza , Cognición , Estudios Cruzados , Femenino , Humanos , Masculino , EnseñanzaRESUMEN
BACKGROUND: Several studies have found depression and depressive feelings to be associated with subsequent dementia. As dementias typically have a long preclinical development phase, it has been difficult to determine whether depression and depressive feelings reflect a concurrent underlying dementia disease, rather than playing a causative role. Our aim was to investigate hopelessness, one dimension of depressive feelings, and evaluate the likelihood of a prodromal versus a causative role of hopelessness feelings in dementia development. METHODS: We invited a random sample of 2000 survivors from a representative population in Eastern Finland, originally investigated in midlife between 1972 and 1987, for re-examination an average of 21 years later. The age of the 1449 persons who accepted the invitation was between 39 and 64 years (mean 50.4 years) in midlife and between 65 and 80 (mean 71.3) at follow-up. To measure feelings of hopelessness in midlife and at follow-up, the participants indicated their level of agreement to two statements about their own possible future. We used logistic regression to investigate the association between the combined scores from these two items and cognitive health at follow-up, while adjusting for several health and life-style variables from midlife and for apolipoprotein E4 (ApoE4) status, depression and hopelessness feelings at follow-up. We compared the associations with late-life cognitive health when feelings of hopelessness were either measured in midlife or at the follow-up. In addition we analyzed the changes in hopelessness scores from midlife to follow-up in participants who were either cognitively healthy or impaired at follow-up. RESULTS: We found higher levels of hopelessness in midlife, but not at follow-up, to be associated with cognitive impairment at follow-up; the adjusted odds ratio for each step of the five-level hopelessness scale was 1.30 (95% confidence interval 1.11-1.51) for any cognitive impairment and 1.37 (1.05-1.78) for Alzheimer's disease. These associations remained significant also after the final adjustments for depressive feelings and for hopelessness at follow-up. The individual changes in hopelessness scores between midlife and follow-up were not systematically related to cognitive health at the follow-up. CONCLUSION: Our results suggest that feelings of hopelessness already in midlife may have long-term implications for cognitive health and increase the risk of Alzheimer's disease in later life.
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Trastornos del Conocimiento/etiología , Cognición , Depresión/complicaciones , Emociones , Adulto , Apolipoproteína E4/genética , Trastornos del Conocimiento/genética , Femenino , Finlandia , Estudios de Seguimiento , Heterocigoto , Humanos , Masculino , Persona de Mediana Edad , Estudios ProspectivosRESUMEN
AIMS: To examine the association between marital status and cognitive impairment among community-dwelling Chinese older adults. METHODS: We analyzed data from 2,498 Chinese aged 55 and older from the Singapore Longitudinal Aging Study cohort. Cognitive impairment was defined as a Mini-Mental State Examination total score of 23 or below. Odds ratios of associations were reported and adjusted for potential confounders in logistic regression models. RESULTS: The prevalence of cognitive impairment was 12.2% (n = 306). Being single was associated with about 2.5 times increased odds of cognitive impairment compared to being married (adjusted OR = 2.53, 95% CI: 1.41-4.55). The association between marital status and cognitive impairment was much stronger in men compared to that in women, and was indeed statistically significant only for men. Among the single and widowed persons social engagement was associated with a lower risk of cognitive impairment. Compared with subjects in the lowest tertile of social engagement scores, the odds of having cognitive impairment was lowered by 50% for subjects in the second and the third tertile. CONCLUSION: Being single or widowed was associated with higher odds of cognitive impairment compared to being married in a cohort of older Chinese men but not women.
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OBJECTIVES: To evaluate whether mid-life marital status is related to cognitive function in later life. DESIGN: Prospective population based study with an average follow-up of 21 years. SETTING: Kuopio and Joensuu regions in eastern Finland. PARTICIPANTS: Participants were derived from random, population based samples previously investigated in 1972, 1977, 1982, or 1987; 1449 individuals (73%), aged 65-79, underwent re-examination in 1998. MAIN OUTCOME MEASURES: Alzheimer's disease and mild cognitive impairment. RESULTS: People cohabiting with a partner in mid-life (mean age 50.4) were less likely than all other categories (single, separated, or widowed) to show cognitive impairment later in life at ages 65-79. Those widowed or divorced in mid-life and still so at follow-up had three times the risk compared with married or cohabiting people. Those widowed both at mid-life and later life had an odds ratio of 7.67 (1.6 to 40.0) for Alzheimer's disease compared with married or cohabiting people. The highest increased risk for Alzheimer's disease was in carriers of the apolipoprotein E e4 allele who lost their partner before mid-life and were still widowed or divorced at follow-up. The progressive entering of several adjustment variables from mid-life did not alter these associations. CONCLUSIONS: Living in a relationship with a partner might imply cognitive and social challenges that have a protective effect against cognitive impairment later in life, consistent with the brain reserve hypothesis. The specific increased risk for widowed and divorced people compared with single people indicates that other factors are needed to explain parts of the results. A sociogenetic disease model might explain the dramatic increase in risk of Alzheimer's disease for widowed apolipoprotein E e4 carriers.