Can lifestyle modification improve neurocognition? Rationale and design of the ENLIGHTEN clinical trial

Exploring the relationship between Nutrition, gUT microbiota, and BRain AgINg in community-dwelling seniors: the Italian NutBrain population-based cohort study protocol

Background

Epidemiological evidence suggests that healthy diet is associated with a slowdown of cognitive decline leading to dementia, but the underlying mechanisms are still partially unexplored. Diet is the main determinant of gut microbiota composition, which in turn impacts on brain structures and functions, however to date no studies on this topic are available. The goal of the present paper is to describe the design and methodology of the NutBrain Study aimed at investigating the association of dietary habits with cognitive function and their role in modulating the gut microbiota composition, and brain measures as well.

Methods/design

This is a population-based cohort study of community-dwelling adults aged 65 years or more living in Northern Milan, Italy. At the point of presentation people are screened for cognitive functions. Socio-demographic characteristics along with lifestyles and dietary habits, medical history, drugs, functional status, and anthropometric measurements are also recorded. Individuals suspected to have cognitive impairment at the screening phase undergo a clinical evaluation including a neurological examination and a Magnetic Resonance Imaging (MRI) scanning (both structural and functional). Stool and blood samples for the gut microbiota analysis and for the evaluation of putative biological markers are also collected. For each subject with a confirmed diagnosis of Mild Cognitive Impairment (MCI), two cognitively intact controls of the same sex and age are visited. We intend to enrol at least 683 individuals for the screening phase and 240 persons for the clinical assessment.

Discussion

The NutBrain is an innovative study that incorporates modern and advanced technologies (i.e. microbiome and neuroimaging) into traditional epidemiologic design. The study represents a unique opportunity to address key questions about the role of modifiable risk factors on cognitive impairment, with a particular focus on dietary habits and their association with gut microbiota and markers of the brain-aging process. These findings will help to encourage and plan lifestyle interventions, for both prevention and treatment, aiming at promoting healthy cognitive ageing.

Trial registration

Trial registration number NCT04461951, date of registration July 7, 2020 (retrospectively registered, ClinicalTrials.gov).

Metabolic and Neurocognitive Changes Following Lifestyle Modification: Examination of Biomarkers from the ENLIGHTEN Randomized Clinical Trial

BACKGROUND

Previous studies have demonstrated that aerobic exercise (AE) and the Dietary Approaches to Stop Hypertension (DASH) diet can improve neurocognition. However, the mechanisms by which lifestyle improves neurocognition have not been widely studied. We examined the associations between changes in metabolic, neurotrophic, and inflammatory biomarkers with executive functioning among participants from the Exercise and Nutritional Interventions for Neurocognitive Health Enhancement (ENLIGHTEN) trial.

OBJECTIVE

To examine the association between changes in metabolic function and neurocognition among older adults with cognitive impairment, but without dementia (CIND) participating in a comprehensive lifestyle intervention.

METHODS

ENLIGHTEN participants were randomized using a 2×2 factorial design to receive AE, DASH, both AE+DASH, or a health education control condition (HE) for six months. Metabolic biomarkers included insulin resistance (homeostatic model assessment [HOMA-IR]), leptin, and insulin-like growth factor (IGF-1); neurotrophic biomarkers included brain derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF); and inflammatory biomarkers included interleukin-6 (IL-6) and C-Reactive Protein (CRP).

RESULTS

Participants included 132 sedentary older adults (mean age = 65 [SD = 7]) with CIND. Results demonstrated that both AE (d = 0.48, p = 0.015) and DASH improved metabolic function (d = 0.37, p = 0.039), without comparable improvements in neurotrophic or inflammatory biomarkers. Greater improvements in metabolic function, including reduced HOMA-IR (B = -2.3 [-4.3, -0.2], p = 0.033) and increased IGF-1 (B = 3.4 [1.2, 5.7], p = 0.004), associated with increases in Executive Function.

CONCLUSION

Changes in neurocognition after lifestyle modification are associated with improved metabolic function.

Pathways of Prevention: A Scoping Review of Dietary and Exercise Interventions for Neurocognition

Alzheimer's disease and related dementias (ADRD) represent an increasingly urgent public health concern, with an increasing number of baby boomers now at risk. Due to a lack of efficacious therapies among symptomatic older adults, an increasing emphasis has been placed on preventive measures that can curb or even prevent ADRD development among middle-aged adults. Lifestyle modification using aerobic exercise and dietary modification represents one of the primary treatment modalities used to mitigate ADRD risk, with an increasing number of trials demonstrating that exercise and dietary change, individually and together, improve neurocognitive performance among middle-aged and older adults. Despite several optimistic findings, examination of treatment changes across lifestyle interventions reveals a variable pattern of improvements, with large individual differences across trials. The present review attempts to synthesize available literature linking lifestyle modification to neurocognitive changes, outline putative mechanisms of treatment improvement, and discuss discrepant trial findings. In addition, previous mechanistic assumptions linking lifestyle to neurocognition are discussed, with a focus on potential solutions to improve our understanding of individual neurocognitive differences in response to lifestyle modification. Specific recommendations include integration of contemporary causal inference approaches for analyzing parallel mechanistic pathways and treatment-exposure interactions. Methodological recommendations include trial multiphase optimization strategy (MOST) design approaches that leverage individual differences for improved treatment outcomes.

Physical exercise for prevention of dementia (EPD) study: background, design and methods

Background

Several observational studies have shown that exercise reduces the risk of cognitive decline; however, evidences from long-term, well-conducted, randomized controlled trials are scanty. The principal aim of this study is to verify whether a long-term program of multimodal supervised exercise improves the cognitive function and/or reduces the rate of cognitive decline in older adults at different degrees of risk for dementia.

Methods/design

EPD is a parallel group, double-blind, randomized controlled trial. Community-dwelling volunteers aged 50 years or more are being recruited from different community centers and screened for eligibility. Enrolled subjects are being divided in 3 groups: a) without subjective or objective cognitive impairment, b) with subjective memory complaints, and c) with mild cognitive impairments. Participants in each group (at least 180) are being randomly assigned (1:1) to an experimental group, performing a supervised training including aerobic and resistance exercises of moderate/high intensity, or to a control group. Primary outcome will be 48-months changes in Mini Mental State Examinations. Secondary outcomes will be changes in several cognitive tests including a composite cognitive score. Time points will be at baseline, and at 6, 12, 24, 36 and 48 months. Statistical analysis will be done as intention to treat, complete case and mixed model analysis.

Discussion

EPD is the first trial to examine the effects of a long exercise program (48 months) on cognitive performances. If successful, this trial may provide evidence for using long-term and multimodal exercise interventions for dementia prevention programs in the aging population.

Trial registration

The study is registered at ClinicalTrials.gov with the code NCT02236416.

Nutrition and other lifestyle influences on arterial aging

As our world's population ages, cardiovascular diseases (CVD) will become an increasingly urgent public health problem. A key antecedent to clinical CVD and many other chronic disorders of aging is age-related arterial dysfunction, characterized by increased arterial stiffness and impaired arterial endothelial function. Accumulating evidence demonstrates that diet and nutrition may favorably modulate these arterial functions with aging, but many important questions remain. In this review, we will summarize the available information on dietary patterns and nutritional factors that have been studied for their potential to reduce arterial stiffness and improve endothelial function with age, with an emphasis on: 1) underlying physiological mechanisms, and 2) emerging areas of research on nutrition and arterial aging that may hold promise for preventing age-related CVD.

Impact of Worsened Metabolic Syndrome on the Risk of Dementia: A Nationwide Cohort Study

BACKGROUND

The relationship of alteration of metabolic syndrome (MetS) with dementia remains unclear. The purpose of study was to evaluate the association between dynamic change in MetS status around a 5-year period and dementia.

METHODS AND RESULTS

The cohort study was conducted from the Taiwanese Survey on Prevalence of Hypertension, Hyperglycemia, and Hyperlipidemia in 2002, with follow-up in 2007. The sample was subsequently linked to the National Health Insurance Research Database. Participants were divided into 3 groups: persistent MetS (MetS both in 2002 and 2007); nonpersistent MetS (MetS either in 2002 or 2007); and non-MetS (MetS neither in 2002 nor 2007). Furthermore, the individuals with nonpersistent MetS were categorized as improved MetS (MetS in 2002 but not in 2007) and worsened MetS (MetS not in 2002 but in 2007). Each participant was tracked until the end of 2011 to identify the development of dementia. In total, 3458 participants aged 40 to 80 years were included. Up to 10 years and 31 741 person-years of follow-up, 76 patients developed dementia. Only a relationship was found between the nonpersistent MetS and dementia (adjusted hazard ratio=1.93; 95% confidence interval =1.17-3.19; P=0.010). Moreover, a significantly higher dementia risk was observed in patients with worsened MetS (adjusted hazard ratio=2.22; 95% confidence interval=1.32-3.72; P=0.003), but not those with persistent (P=0.752) or improved (P=0.829) MetS. Similar results were detected in participants aged ≥65 years.

CONCLUSIONS

Patients with worsened MetS had an increased dementia risk during the 10-year follow-up period in a population-based sample.

Alzheimer's Disease: An Overview of Recent Developments and a Look to the Future

Alzheimer's disease is a major public health concern, affecting an estimated 40 million people worldwide. Over the past few years, several new diagnostic tests and new diagnostic nomenclatures have emerged, and more than 70 disease-modifying agents are in clinical trials. Naturalistic studies that include biomarkers-such as genomics, metabolomics, and imaging-have yielded additional insights into disease mechanisms and timelines of preclinical disease onset. This article reviews recent developments in epidemiology, diagnostic criteria, and diagnostic tests; provides updates on symptomatic therapies, ongoing prevention trials, and neuropsychiatric symptom treatment options; and ends with a discussion on prospects for a cure.

Lifestyle and Neurocognition in Older Adults With Cardiovascular Risk Factors and Cognitive Impairment

OBJECTIVE

The aim of the study was to determine the relationship of lifestyle factors and neurocognitive functioning in older adults with vascular risk factors and cognitive impairment, no dementia (CIND).

METHODS

One hundred sixty adults (M [SD] = 65.4 [6.8] years) with CIND completed neurocognitive assessments of executive function, processing speed, and memory. Objective measures of physical activity using accelerometry, aerobic capacity determined by exercise testing, and dietary habits quantified by the Food Frequency Questionnaire and 4-Day Food Diary to assess adherence to the Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets were obtained to assess direct effects with neurocognition. Potential indirect associations of high-sensitivity C-reactive protein and the Framingham Stroke Risk Profile also were examined.

RESULTS

Greater aerobic capacity (β = 0.24) and daily physical activity (β = 0.15) were associated with better executive functioning/processing speed and verbal memory (βs = 0.24; 0.16). Adherence to the DASH diet was associated with better verbal memory (β = 0.17). Greater high-sensitivity C-reactive protein (βs = -0.14; -0.21) and Framingham Stroke Risk Profile (β = -0.18; -0.18) were associated with poorer executive functioning/processing speed and verbal memory. Greater stroke risk partially mediated the association of aerobic capacity with executive functioning/processing speed, and verbal memory and greater inflammation partially mediated the association of physical activity and aerobic fitness, with verbal memory.

CONCLUSIONS

Higher levels of physical activity, aerobic fitness, and adherence to the DASH diet are associated with better neurocognitive performance in adults with CIND. These findings suggest that the adoption of healthy lifestyle habits could reduce the risk of neurocognitive decline in vulnerable older adults.

CLINICAL TRIAL REGISTRATION

NCT01573546.

Role of fruits, nuts, and vegetables in maintaining cognitive health

Population aging is leading to an increase in the incidence of age-related cognitive dysfunction and, with it, the health care burden of caring for older adults. Epidemiological studies have shown that consumption of fruits, nuts, and vegetables is positively associated with cognitive ability; however, these foods, which contain a variety of neuroprotective phytochemicals, are widely under-consumed. Surprisingly few studies have investigated the effects of individual plant foods on cognitive health but recent clinical trials have shown that dietary supplementation with individual foods, or switching to a diet rich in several of these foods, can improve cognitive ability. While additional research is needed, increasing fruit, nut, and vegetable intake may be an effective strategy to prevent or delay the onset of cognitive dysfunction during aging.

Higher Physical Activity Is Associated with Increased Attentional Network Connectivity in the Healthy Elderly

The purpose of this study was to demonstrate the potential alterations in structural network properties related to physical activity (PA) in healthy elderly. We recruited 76 elderly individuals with normal cognition from Samsung Medical Center in Seoul, Korea. All participants underwent the Cambridge Neuropsychological Test Automated Battery and 3.0T brain magnetic resonance imaging (MRI). Participants were subdivided into quartiles according to the International Physical Activity Questionnaire scores, which represents the amount of PA. Through graph theory based analyses, we compared global and local network topologies according to PA quartile. The higher PA group demonstrated better performance in speed processing compared to the lower PA group. Regional nodal strength also significantly increased in the higher PA group, which involved the bilateral middle frontal, bilateral inferior parietal, right medial orbitofrontal, right superior, and middle temporal gyri. These results were further replicated when the highest and the lowest quartile groups were compared in terms of regional nodal strengths and local efficiency. Our findings that the regional nodal strengths associated with the attentional network were increased in the higher PA group suggest the preventive effects of PA on age-related cognitive decline, especially in attention.

Prevention of Age-Related Cognitive Decline: Which Strategies, When, and for Whom?

Brain aging is characterized by the progressive and gradual accumulation of detrimental changes in structure and function, which increase risk of age-related cognitive decline and dementia. This devastating chronic condition generates a huge social and economic burden and accounts for 11.2% of years of disability. The increase in lifespan has contributed to the increase in dementia prevalence; however, there is currently no curative treatment for most causes of dementias. This paper reviews evidence-based strategies to build, enhance, and preserve cognition over the lifespan by examining approaches that work best, proposing when in the life course they should be implemented, and in which population group(s). Recent work shows a tendency to decreased age-specific prevalence and incidence of cognitive problems and dementia among people born later in the first half of the 20th century, citing higher educational levels, improvements in lifestyle, and better handling of vascular risk factors. This implies that we can target modifiable environmental, lifestyle, and health risk factors to modify the trajectory of cognitive decline before the onset of irreversible dementia. Because building cognitive reserve and prevention of cognitive decline are of critical importance, interventions are needed at every stage of the life course to foster cognitive stimulation, and enable healthy eating habits and physical activity throughout the lifespan. Preventive interventions to decrease and delay cognitive decline and its consequences in old age will also require collaboration and action on the part of policy-makers at the political and social level.

Dietary Factors and Cognitive Decline

Cognitive decline is an increasingly important public health problem, with more than 100 million adults worldwide projected to develop dementia by 2050. Accordingly, there has been an increased interest in preventive strategies that diminish this risk. It has been recognized that lifestyle factors including dietary patterns, may be important in the prevention of cognitive decline and dementia in later life. Several dietary components have been examined, including antioxidants, fatty acids, and B vitamins. In addition, whole dietary eating plans, including the Mediterranean diet (MeDi), and the Dietary Approaches to Stop Hypertension (DASH) diet, with and without weight loss, have become areas of increasing interest. Although prospective epidemiological studies have observed that antioxidants, fatty acids, and B vitamins are associated with better cognitive functioning, randomized clinical trials have generally failed to confirm the value of any specific dietary component in improving neurocognition. Several randomized trials have examined the impact of changing 'whole' diets on cognitive outcomes. The MeDi and DASH diets offer promising preliminary results, but data are limited and more research in this area is needed.

Small vessel disease and memory loss: what the clinician needs to know to preserve patients' brain health

Small vessel disease (SVD) in the brain manifests in the periventricular and deep white matter and radiographically is described as "leukoaraiosis". It is increasingly recognized as a cause of morbidity from middle age onward and this clinical relevance has paralleled advances in the field of neuroradiology. Overall, SVD is a heterogenous group of vascular disorders that may be asymptomatic, or a harbinger of many conditions that jeopardize brain health. Management and prevention focuses on blood pressure control, lifestyle modification, and symptomatic treatment.

Arterial stiffness, the brain and cognition: a systematic review

BACKGROUND

Arterial stiffness is a known predictor of cardiovascular disease, and has also been associated with markers of cerebral small vessel disease as well as poor cognitive function and cognitive decline. The consistency of these associations and their relationship to each other are unclear.

METHOD

We conducted a systematic review of the evidence associating arterial stiffness with cognitive function and cognitive decline, and with makers of cerebral small vessel disease, specifically lacunar infarcts and white matter hyperintensities.

RESULTS

Thirteen cross-sectional studies examining arterial stiffness and white matter hyperintensities or lacunar infarctions reported a positive association between increased arterial stiffness and radiological findings of cerebral small vessel disease. Two longitudinal studies examining the relationship between arterial stiffness and white matter hyperintensities found increased pulse wave velocity to be an independent predictor of white matter hyperintensity volume. Fifteen cross-sectional and seven longitudinal studies examining arterial stiffness and cognition were identified. Fourteen of the fifteen cross-sectional studies associated increased arterial stiffness with lower cognitive function, and six of the seven longitudinal studies found arterial stiffness to be predictive of cognitive decline.

CONCLUSION

Arterial stiffness is associated with cerebral small vessel disease and decreased cognitive function. However methodological limitations such as differing covariates between studies and an over-reliance on the MMSE to measure cognition are a concern across much of the literature.

Impact of aerobic exercise on neurobehavioral outcomes

Numerous studies have examined the relationship between physical activity and cognitive function, demonstrating that greater physical activity is associated with lower incidence of cognitive impairment in later life. Due to an increasingly large number of older adults at risk for cognitive impairment, the relationship between physical activity and cognition has garnered increasing public health relevance and multiple randomized trials have demonstrated that exercise interventions among sedentary adults improve cognitive performance in multiple domains of function. This article will examine the relationship between physical activity and cognitive function by reviewing several different areas of literature, including the prevalence of cognitive impairment, assessment methods, observational studies examining physical activity and cognition, and intervention studies. The present review is intended to provide a historical tutorial of existing literature linking physical activity, exercise, and cognitive function among both healthy and clinical populations.