Randomized trial of the effects of cholesterol-lowering dietary treatment on psychological function

Effect of Low-Fat Diet on Depression Score in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials

CONTEXT

Current evidence on the effect of a low-fat (LF) diet on depression scores has been inconsistent.

OBJECTIVE

To explore the effect of an LF diet on depression scores of adults by systematic review and meta-analysis of randomized controlled trials (RCTs).

DATA SOURCES

The PubMed, ISI Web of Science, Scopus, and CENTRAL databases were searched from inception to June 7, 2023, to identify trials investigating the effect of an LF diet (fat intake ≤30% of energy intake) on the depression score.

DATA EXTRACTION

Random-effects meta-analyses were used to estimate pooled summary effects of an LF diet on the depression score (as Hedges g).

DATA ANALYSIS

Finding from 10 trials with 50 846 participants indicated no significant change in depression score following LF diets in comparison with usual diet (Hedges g = -0.11; 95% CI, -0.25 to 0.03; P = 0.12; I2 = 70.7% [for I2, 95% CI, 44%, 85%]). However, a significant improvement was observed in both usual diet and LF diets when the content of protein was 15-20% of calorie intake (LF, normal protein diet: n = 5, Hedges g = -0.21, 95% CI, -0.24 to -0.01, P = 0.04, I2 = 0%; usual, normal protein diet: n = 3, Hedges g = -0.28, 95% CI, -0.51 to -0.05, P = 0.01, I2 = 0%). Sensitivity analysis also found the depression score improved following LF diet intervention in participants without baseline depression.

CONCLUSION

This study revealed that LF diet may have small beneficial effect on depression score in the studies enrolled mentally healthy participants. Moreover, achieving to adequate dietary protein is likely to be a better intervention than manipulating dietary fat to improve depression scores. However, it is not clear whether this effect will last in the long term. Conducting more studies may change the results due to the low-certainty of evidence.

SYSTEMATIC REVIEW REGISTRATION

CRD42023420978 (https://www.crd.york.ac.uk/PROSPERO).

The impact of continuous calorie restriction and fasting on cognition in adults without eating disorders

Research into the effects of calorie restriction continues to intrigue those interested in whether it may allow humans to live longer and healthier lives. Animal studies of continuous calorie restriction (CCR) and fasting have demonstrated substantial advantages to health and longevity. However, concerns remain about the impact of restricting calorie intake on human health and cognition. Given the emerging evidence of cognitive impairments in eating disorders, studies investigating restricted calorie intake in healthy humans (in an ethical way) may also have implications for understanding restrictive eating disorders. In this review, the published literature on the impact of CCR and fasting on cognitive function in healthy human participants is synthesized. Of the 33 studies of CCR and fasting in humans identified, 23 demonstrated significant changes in cognition. Despite variation across the cognitive domains, results suggest CCR benefits inhibition, processing speed, and working memory, but may lead to impairments in cognitive flexibility. The results of fasting studies suggest fasting is associated with impairments in cognitive flexibility and psychomotor abilities. Overall, the results of these studies suggest the degree (ie, the severity) of calorie restriction is what most likely predicts cognitive improvements as opposed to impairments. For individuals engaging in sustained restriction, this may have serious, irreversible consequences. However, there are mixed findings regarding the impact of CCR and fasting on this aspect of human functioning, suggesting further research is required to understand the costs and benefits of different types of calorie restriction.

Practical dietary interventions to prevent cardiovascular disease suitable for implementation in primary care: an ADAPTE-guided systematic review of international clinical guidelines

PURPOSE

Cardiovascular diseases (CVD) are the leading cause of death globally. The current model of care for high-income countries involves preventive medication and highly trained healthcare professionals, which is expensive and not transposable to low-income countries. An innovative, effective approach adapted to limited human, technical, and financial resources is required. Measures to reduce CVD risk factors, including diet, are proven to be effective. The survey "Scaling-up Packages of Interventions for Cardiovascular disease prevention in selected sites in Europe and Sub-Saharan Africa" aims to develop non-pharmacological cardiovascular prevention and control programs in primary care and community settings in high, middle, and low-income countries. This review aims to identify the existing, validated dietary interventions for primary CVD prevention from national and international clinical guidelines that can be implemented in primary care and communities.

METHODS

A systematic review of CVD prevention guidelines was conducted between September 2017 and March 2023 using the Turning Research Into Practice medical database, the Guidelines International Network, and a purposive search. The ADAPTE procedure was followed. Two researchers independently conducted the searches and appraisals. Guidelines published after 01/01/2012 addressing non-pharmacological, dietary interventions for primary CVD prevention or CVD risk factor management, in the adult general population in primary care or in community settings were included and appraised using the Appraisal of Guidelines Research and Evaluation II score. Individual dietary recommendations and the studies supporting them were extracted. Then supporting data about each specific dietary intervention were extracted into a matrix.

RESULTS

In total, 1375 guidelines were identified, of which 39 were included. From these, 383 recommendations, covering 10 CVD prevention themes were identified. From these recommendations, 165 studies for effective dietary interventions for CVD prevention were found. Among these, the DASH diet was the most effective on multiple CVD risk factors. Combining diet with other interventions such as exercise and smoking cessation increased efficacy. No guidelines provided detailed implementation strategies.

CONCLUSION

The DASH diet combined with other interventions was the most effective on an individual basis. However, expansion in the wider population seems difficult, without government support to implement regulations such as reducing salt content in processed food.

TRIAL REGISTRATION

Clinical Trials NCT03886064.

Mediterranean Diet, Ketogenic Diet or MIND Diet for Aging Populations with Cognitive Decline: A Systematic Review

(1) Background: Compelling evidence shows that dietary patterns can slow the rate of cognitive decline, suggesting diet is a promising preventive measure against dementia. (2) Objective: This systematic review summarizes the evidence of three dietary patterns, the Mediterranean diet, the ketogenic diet and the MIND diet, for the prevention of cognitive decline. (3) Methods: A systematic search was conducted in major electronic databases (PubMed, ScienceDirect and Web of Science) up until 31 January 2022, using the key search terms "Mediterranean diet", "ketogenic diet", "MIND diet", "dementia", "cognition" and "aging". A statistical analysis was performed using RoB 2 and the Jadad scale to assess the risk of bias and methodological quality in randomized controlled trials. (4) Results: Only RCTs were included in this study; there were eleven studies (n = 2609 participants) of the Mediterranean diet, seven studies (n = 313) of the ketogenic diet and one study (n = 37) of the MIND diet. The participants' cognitive statuses were normal in seven studies, ten studies included patients with mild cognitive impairments and two studies included Alzheimer's disease patients. (5) Conclusion: All three dietary interventions have been shown to slow the rate of cognitive decline in the included studies. The Mediterranean diet was shown to be beneficial for global cognition after 10 weeks of adherence, the ketogenic diet had a beneficial effect for patients with diabetes mellitus and improved verbal recognition, while the MIND diet showed benefits in obese patients, improving working memory, verbal recognition, memory and attention.

Association Between Dietary and Serum Cholesterol and Cognitive Function Among the U.S. Elderly from NHANES 2011-2014

BACKGROUND

The association between dietary or serum cholesterol and cognitive performance in older adults has not been well-established.

OBJECTIVE

This study aimed to investigate the potential association between dietary or serum cholesterol and cognitive performance in the elderly population.

METHODS

A cross-sectional analysis was conducted using data from the National Health and Nutrition Examination Survey (NHANES) 2011-2012 and 2013-2014. Diet and supplement cholesterol was estimated based on two non-consecutive 24-hour dietary recalls. Cognitive function was assessed using various statistical tests. Poor cognitive performance was defined as scores below the lowest quartile within age groups. Regression models were adjusted for demographic factors, and subgroup analyses were performed for non-Hispanic White (NHW) and non-Hispanic Black (NHB) individuals.

RESULTS

Among 759 participants aged 60 years and above, dietary cholesterol was only associated with dietary saturated fatty acids and serum high-density lipoprotein cholesterol. There was no evidence of an association between dietary cholesterol and cognitive function, except for NHB individuals, where dietary cholesterol showed a positive correlation with cognitive function. In the overall sample and NHW participants, there were consistent positive associations between serum total cholesterol and cognitive performance across statistical tests, while such associations were rare among NHB individuals. Although not statistically significant, NHB individuals had higher dietary/supplementary/total cholesterol intake compared with NHW individuals.

CONCLUSION

Within the normal range, increasing serum cholesterol may be a potential factor to prevent or relieve cognitive dysfunction. However, ethnic differences should be taken into account when considering the association between cholesterol and cognitive performance.

Efficacy of an adjuvant non-face-to-face multimodal lifestyle modification program for patients with treatment-resistant major depression: A randomized controlled trial

BACKGROUND

The high prevalence of depression is partly attributable to the poor response of patients to first-line antidepressants. Multimodal programs that promote a healthy lifestyle are successful in treating depression when used as a complementary therapy, but their medium- and long-term benefits have not been demonstrated for patients with treatment-resistant depression (TRD). The main aim of this study was to compare the effectiveness of a lifestyle modification program (LMP) with mindfulness-based cognitive therapy (MBCT) and a placebo-control (written suggestions for lifestyle changes) in Spanish patients with TRD.

METHODS

This controlled clinical trial randomized 94 patients with TRD into 3 arms. The primary outcome was the Beck Depression Inventory-II (BDI-II) score at baseline, 2, 6 and 12 months. The secondary outcomes were changes in scores that evaluated quality-of-life, adherence to the Mediterranean diet, physical activity, and social support.

RESULTS

Relative to the placebo group, the LMP and MBCT groups had significantly better quality of life (p = 0.017; p = 0.027), and the LMP group had significantly better adherence to the Mediterranean diet (p<0.001) and reduced use of antidepressants (p = 0.036). However, the three groups showed no significant differences in BDI-II score.

LIMITATIONS

Only about half of the planned 180 patients were recruited, in part due to the COVID-19 pandemic.

CONCLUSIONS

There was no evidence that the LMP treatment significantly reduced symptoms of depression relative to the other groups during the COVID-19 lockdown.

Properties of the Cognitive Function Battery for the MIND Diet Intervention to Prevent Alzheimer's Disease

OBJECTIVE

To evaluate the properties of the cognitive battery used in the MIND Diet Intervention to Prevent Alzheimer's Disease. The MIND Diet Intervention is a randomized control trial to determine the relative effectiveness of the MIND diet in slowing cognitive decline and reducing brain atrophy in older adults at risk for Alzheimer's dementia.

METHODS

The MIND cognitive function battery was administered at baseline to 604 participants of an average age of 70 years, who agreed to participate in the diet intervention study, and was designed to measure change over time. The battery included 12 cognitive tests, measuring the 4 cognitive domains of executive function, perceptual speed, episodic memory, and semantic memory. We conducted a principal component analysis to examine the consistency between our theoretical domains and the statistical performance of participants in each domain. To further establish the validity of each domain, we regressed the domain scores against a late-life cognitive activity score, controlling for age, race, sex, and years of education.

RESULTS

Four factors emerged in the principal component analyses that were similar to the theoretical domains. In regression equations, we found the expected associations with age, education, and late-life cognitive activity with each of the four cognitive domains.

CONCLUSIONS

These results indicate that the MIND cognitive battery is a comprehensive and valid battery of four separate domains of cognitive function that can be used in diet intervention trials for older adults.

Assessing the Physiological Effects of Traditional Regional Diets Targeting the Prevention of Cardiovascular Disease: A Systematic Review of Randomized Controlled Trials Implementing Mediterranean, New Nordic, Japanese, Atlantic, Persian and Mexican Dietary Interventions

Traditional regional diets are considered as sustainable dietary patterns, while many have been examined with regard to their health benefits. The aim of the present systematic review was to aggerate all evidence on the physiological effects of regional diets among adults at high risk for cardiovascular disease (CVD). Three databases were searched for randomized controlled trials (RCTs) implementing any regional diet (Mediterranean (MedD), Persian, Southern European Atlantic, Japanese, Chinese, new Nordic, or other) while examining cardiovascular risk factors among adults at increased risk. Primary outcomes included anthropometric indices and secondary outcomes involved blood lipid concentrations, glucose metabolism, inflammation and other markers of CVD progression. Twenty RCTs fulfilled the study’s criteria and were included in the qualitative synthesis, with the majority implementing a MedD. Adherence to most of the regional diets induced a reduction in the BW and anthropometric indices of the participants. The majority of RCTs with blood pressure endpoints failed to note a significant reduction in the intervention compared to the comparator arm, with the exception of some new Nordic and MedD ones. Despite the interventions, inflammation markers remained unchanged except for CRP, which was reduced in the intervention groups of one new Nordic, the older Japanese, and the Atlantic diet RCTs. With regard to blood lipids, regional diet interventions either failed to induce significant differences or improved selective blood lipid markers of the participants adhering to the experimental regional diet arms. Finally, in the majority of RCTs glucose metabolism failed to improve. The body of evidence examining the effect of regional dietary patterns on CVD risk among high-risk populations, while employing an RCT design, appears to be limited, with the exception of the MedD. More research is required to advocate for the efficacy of most regional diets with regard to CVD.

A Critical Review of the Study of Neuroprotective Diets to Reduce Cognitive Decline

Alzheimer’s disease (AD) and other dementias are now the seventh leading cause of death in the world and are projected to affect 115.4 million people by 2050. Delaying the onset of AD by just five years is estimated to reduce the cost and prevalence of the disease by half. There is no cure for AD nor any drug therapies to halt its progression once the disease begins. Lifestyle choices including diet are being seen as a viable complementary therapy to reduce cognitive decline, the hallmark of AD. Mediterranean, DASH (Dietary Approaches to Stop Hypertension), and MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) diets have biological mechanisms supporting their potential neuroprotective benefits, but the findings of study outcomes about these benefits have been inconsistent. This paper analyzed five Randomized Clinical Trials (RCTs) (from 2000 to 2021) and 27 observational studies (from 2010 to 2021) focused on the link between cognitive health and the Mediterranean/DASH/MIND diets to identify gaps and challenges that could lead to inconsistent results. These include a lack of accuracy in assessing food intake, multiple dietary pattern scoring systems, a shifting metric among studies focused on the Mediterranean diet, a lack of standards in the tools used to assess cognitive decline, and studies that were underpowered or had follow-up periods too short to detect cognitive change. Insights from these gaps and challenges are summarized in recommendations for future RCTs, including both pragmatic and explanatory RCTs.

Healthy Lifestyle and Cognition: Interaction between Diet and Physical Activity

PURPOSE OF REVIEW

This review discusses current research on the impact of specific dietary patterns and exercise, both individually and combined, on cognitive function in older adults.

RECENT FINDINGS

Observational evidence generally supports a relationship between diet adherence and positive cognitive outcomes related to memory, executive function, and risk for cognitive impairment; however, randomized controlled trials (RCTs) are limited. Exercise research is more extensive, showing improvements in cognitive performance after exercise interventions regardless of baseline cognitive status and noting lower incidences of cognitive impairment in people who engage in regular physical activity. Evidence supports adherence to specific dietary patterns and a combination of aerobic and resistance exercise as an effective approach to mitigate age-associated cognitive decline. Further research on older adults at various stages of cognitive decline, as well as longer-term RCTs, will help determine the best clinical markers of early cognitive dysfunction, and the effectiveness of early lifestyle intervention on cognitive function.

The Effect of the Mediterranean Diet on Metabolic Health: A Systematic Review and Meta-Analysis of Controlled Trials in Adults

The Mediterranean diet (MD) may provide metabolic benefits but no systematic review to date has examined its effect on a multitude of outcomes related to metabolic health. This systematic review with meta-analysis (International Prospective Register of Systematic Reviews, PROSPERO; number CRD42019141459) aimed to examine the MD’s effect on metabolic syndrome (MetSyn) incidence, components and risk factors (primary outcomes), and incidence and/or mortality from MetSyn-related comorbidities and receipt of pharmacologic treatment for MetSyn components and comorbidities (secondary outcomes). We searched Pubmed, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Web of Science for controlled trials published until June 2019, comparing the MD with no treatment, usual care, or different diets in adults. Studies not published in English and not promoting the whole MD were excluded. Two authors independently extracted data and assessed risk of bias using the Cochrane Collaboration’s and Risk of Bias in non-randomised studies (ROBINS-I) tools. Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Random-effects meta-analyses, subgroup analyses and meta-regressions were performed, and heterogeneity was quantified using the I² statistic. We identified 2654 reports and included 84 articles reporting 57 trials (n = 36,983). In random effects meta-analyses, the MD resulted in greater beneficial changes in 18 of 28 MetSyn components and risk factors (body weight, body mass index, waist circumference, systolic and diastolic blood pressure, glucose, insulin, homeostatic model assessment of insulin resistance (HOMA-IR) index, total-, low-density lipoprotein (LDL)- and high-density lipoprotein (HDL)-cholesterol, triglycerides, alanine transaminase, hepatic fat mass, C-reactive protein, interleukin-6, tumour necrosis factor-a, and flow-mediated dilatation) and lower risk of cardiovascular disease incidence (risk ratio (RR) = 0.61, 95% confidence intervals (CI) 0.42–0.80; I² = 0%), and stroke (RR = 0.67, 95% CI 0.35–0.98; I² = 0%). Only six studies reported effects on pharmacotherapy use, and pooled analysis indicated no differences between diet groups. Lack of consistency in comparator groups and other study characteristics across studies resulted in high heterogeneity for some outcomes, which could not be considerably explained by meta-regressions. However, a consistent direction of beneficial effect of the MD was observed for the vast majority of outcomes examined. Findings support MD’s beneficial effect on all components and most risk factors of the MetSyn, in addition to cardiovascular disease and stroke incidence. More studies are needed to establish effects on other clinical outcomes and use of pharmacotherapy for MetSyn components and comorbidities. Despite the high levels of heterogeneity for some outcomes, this meta-analysis enabled the comparison of findings across studies and the examination of consistency of effects. The consistent direction of effect, suggesting the MD’s benefits on metabolic health, supports the need to promote this dietary pattern to adult populations.

Diet, Stress and Mental Health

Introduction: There has long been an interest in the effects of diet on mental health, and the interaction of the two with stress; however, the nature of these relationships is not well understood. Although associations between diet, obesity and the related metabolic syndrome (MetS), stress, and mental disorders exist, causal pathways have not been established. Methods: We reviewed the literature on the relationship between diet, stress, obesity and psychiatric disorders related to stress. Results: Diet and obesity can affect mood through direct effects, or stress-related mental disorders could lead to changes in diet habits that affect weight. Alternatively, common factors such as stress or predisposition could lead to both obesity and stress-related mental disorders, such as depression and posttraumatic stress disorder (PTSD). Specific aspects of diet can lead to acute changes in mood as well as stimulate inflammation, which has led to efforts to assess polyunsaturated fats (PUFA) as a treatment for depression. Bidirectional relationships between these different factors are also likely. Finally, there has been increased attention recently on the relationship between the gut and the brain, with the realization that the gut microbiome has an influence on brain function and probably also mood and behavior, introducing another way diet can influence mental health and disorders. Brain areas and neurotransmitters and neuropeptides that are involved in both mood and appetite likely play a role in mediating this relationship. Conclusions: Understanding the relationship between diet, stress and mood and behavior could have important implications for the treatment of both stress-related mental disorders and obesity.

Mediterranean-Style Diet for the Primary and Secondary Prevention of Cardiovascular Disease: A Cochrane Review

Background:

Diet plays a major role in cardiovascular disease (CVD) risk.

Objectives:

To determine the effectiveness of a Mediterranean-style diet for the primary and secondary prevention of CVD.

Methods:

We searched for randomised controlled trials (RCTs) of Mediterranean-style diets in healthy adults and those at increased risk of CVD (primary prevention) and with established CVD (secondary prevention).

Results:

Thirty RCTs were included, 22 in primary prevention and eight in secondary prevention. Clinical endpoints were reported in two trials where there was moderate quality evidence for a reduction in strokes for primary prevention, and low quality evidence for a reduction in total and CVD mortality in secondary prevention. We found moderate quality evidence of improvement in CVD risk factors for primary prevention and low quality evidence of little or no effect in secondary prevention.

Conclusions:

There is still some uncertainty regarding the effects of a Mediterranean-style diet in CVD prevention.

NHANES 2011-2014 Reveals Cognition of US Older Adults may Benefit from Better Adaptation to the Mediterranean Diet

Although the Mediterranean diet (MedD) has gained interest for potential Alzheimer’s disease (AD) prevention, it is unknown how well US older adults follow a MedD. We used two National Health and Nutrition Examination Survey (NHANES) cycles (2011–2014) to conduct our primary aim of reporting population estimates of MedD adherence among older adults (60+ years) in the US (n = 3068). The mean MedD adherence score for US older adults was 5.3 ± 2.1 (maximum possible = 18), indicating that older adults in the US do not adhere to a MedD. There were various differences in MedD scores across demographic characteristics. We also assessed the cross-sectional relationship between MedD adherence and cognitive performance using survey-weighted ordinary least squares regression and binary logistic regression models adjusted for 11 covariates. Compared to the lowest MedD adherence tertile, the highest tertile had a lower odds ratio of low cognitive performance on three of five cognitive measures (p < 0.05 for each). Sensitivity analyses within participants without subjective memory complaints over the past year revealed similar results on the same three cognitive measures. We conclude that MedD interventions are a departure from usual dietary intake of older adults in the US and are a reasonable approach for AD prevention trials.

Editorial Comment on Firth et al. (2019)

This Editorial Comment addresses an article by Firth et al. published in the February issue of 2019.

Dietary Patterns and Cognitive Decline: key features for prevention

The decline in cognitive function is generally the result of the complex interaction of several factors. First of all, age, but also demographic, educational, genetic, socio-economic, and environmental determinants, including nutrition. Cognitive decline and dementia prevalence are increasing, and they are projected to continue increasing in the next decades due to the aging of the world population. Currently, there are no effective pharmacological treatments for these devastating and disabling conditions, which emphasize the key role of preventive strategies. There is compelling evidence of the role of diet and lifestyle on cognitive function. Therefore, dietary/ nutritional approaches that contribute to prevent, or slow cognitive decline may have a remarkable public health impact. Numerous studies have explored the role of dietary components and patterns on age-associated cognitive decline, with accruing evidence that combinations of foods and nutrients can have synergistic effects beyond those attributable to individual foods or nutrients. Dietary patterns show the strongest evidence for slowing the development of cognitive decline, Alzheimer's disease and other dementias including the Mediterranean diet, the Dietary Approaches to Stop Hypertension diet, and their combination (the MedDiet-DASH Intervention for Neurodegenerative Delay - MIND), among others with few positive results. There are also dietary patterns with no evidence of such effects. This review examines the evidence for the effects of some dietary patterns as neuroprotective with a potential to delay cognitive decline and the onset of dementia.

Associations of Lipid Levels and Cognition: Findings from the Hispanic Community Health Study/Study of Latinos

OBJECTIVE

Hispanics/Latinos in the United States are less aware of their cholesterol levels and have a higher burden of associated adverse cardiovascular and cerebrovascular outcomes than non-Latino whites. Investigations of the associations between cholesterol levels and cognition in this population have often occurred within the context of metabolic syndrome and are limited to select lipids despite the fact that triglycerides (TGs) may be more relevant to the health of Hispanics/Latinos.

METHODS

Baseline data from the Hispanic Community Health Study/Study of Latinos, collected from 2008 to 2011, was used to investigate the associations of lipid levels (i.e., TG, total cholesterol, TC; low-density and high-density lipoprotein cholesterol, LDL-C and HDL-C) with cognition (i.e., learning, memory, verbal fluency, and digit symbol substitution, DSS), adjusting for relevant confounders.

RESULTS

In 7413 participants ages 45 to 74 years from Central American, Cuban, Dominican, Mexican, Puerto Rican, and South American backgrounds, separate, fully adjusted linear regression models revealed that TG levels were inversely associated with DSS performance; however, this relationship was no longer significant once additional cardiovascular disease risk factors were added to the model (p = .06). TC and LDL-C levels (separately) were positively associated with learning and verbal fluency regardless of adjustments (p-values < .05). Separate analyses investigating the effect modification by background and sex revealed a particularly robust association between TC levels and DSS performance for Puerto Ricans and Central Americans (albeit in opposite directions) and an inverse relationship between TG levels and DSS performance for women (p-values < .02).

CONCLUSIONS

It is important to consider individual lipid levels and demographic characteristics when investigating associations between cholesterol levels and cognition in Hispanics/Latinos.

The Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) Diets Are Associated with Less Cognitive Decline and a Lower Risk of Alzheimer's Disease-A Review

As there is currently no cure for dementia, there is an urgent need for preventive strategies. The current review provides an overview of the existing evidence examining the associations of the Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diets and their dietary components with cognitive decline, dementia, and Alzheimer's disease (AD). A systematic search was conducted within Ovid Medline for studies published up to 27 March 2019 and reference lists from existing reviews and select articles were examined to supplement the electronic search results. In total, 56 articles were included. Higher adherence to the Mediterranean diet was associated with better cognitive scores in 9 of 12 cross-sectional studies, 17 of 25 longitudinal studies, and 1 of 3 trials. Higher adherence to the DASH diet was associated with better cognitive function in 1 cross-sectional study, 2 of 5 longitudinal studies, and 1 trial. Higher adherence to the MIND diet was associated with better cognitive scores in 1 cross-sectional study and 2 of 3 longitudinal studies. Evidence on the association of these dietary patterns with dementia in general was limited. However, higher adherence to the Mediterranean diet was associated with a lower risk of AD in 1 case-control study and 6 of 8 longitudinal studies. Moreover, higher adherence to the DASH or MIND diets was associated with a lower AD risk in 1 longitudinal study. With respect to the components of these dietary patterns, olive oil may be associated with less cognitive decline. In conclusion, current scientific evidence suggests that higher adherence to the Mediterranean, DASH, or MIND diets is associated with less cognitive decline and a lower risk of AD, where the strongest associations are observed for the MIND diet.

Potential for diet to prevent and remediate cognitive deficits in neurological disorders

The pathophysiology of many neurological disorders involves oxidative stress, neuroinflammation, and mitochondrial dysfunction. There is now substantial evidence that diet can decrease these forms of pathophysiology, and an emerging body of literature relatedly suggests that diet can also prevent or even remediate the cognitive deficits observed in neurological disorders that exhibit such pathology (eg, Alzheimer's disease, multiple sclerosis, age-related cognitive decline, epilepsy). The current review summarizes the emerging evidence in relation to whole diets prominent in the scientific literature-ketogenic, caloric restriction, high polyphenol, and Mediterranean diets-and provides a discussion of the possible underlying neurophysiological mechanisms.

The Effects of Dietary Improvement on Symptoms of Depression and Anxiety: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

Poor diet can be detrimental to mental health. However, the overall evidence for the effects of dietary interventions on mood and mental well-being has yet to be assessed. We conducted a systematic review and meta-analysis examining effects of dietary interventions on symptoms of depression and anxiety.

METHODS

Major electronic databases were searched through March 2018 for all randomized controlled trials of dietary interventions reporting changes in symptoms of depression and/or anxiety in clinical and nonclinical populations. Random-effects meta-analyses were conducted to determine effect sizes (Hedges' g with 95% confidence intervals [CI]) for dietary interventions compared with control conditions. Potential sources of heterogeneity were explored using subgroups and meta-regression analyses.

RESULTS

Results: Sixteen eligible randomized controlled trials (published in English) with outcome data for 45,826 participants were included; the majority of which examined samples with nonclinical depression (n = 15 studies). Nonetheless, dietary interventions significantly reduced depressive symptoms (g = 0.162, 95% CI = 0.055 to 0.269, p = 0.003). Similar effects were observed among high-quality trials (g = 0.171, 95% C.I.=0.057 to 0.286, p=0.003) and when compared with both inactive (g = 0.114, 95% C.I.=0.008 to 0.219, p=0.035) and active controls (g = 0.224, 95% C.I.= 0.052 to 0.397, p = 0.011). No effect of dietary interventions was observed for anxiety (k = 11, n = 2270, g = 0.085, 95% C.I. = -0.031 to 0.202, p=0.151). Studies with female samples observed significantly greater benefits from dietary interventions, for symptoms of both depression and anxiety.

CONCLUSIONS

Dietary interventions hold promise as a novel intervention for reducing symptoms of depression across the population. Future research is required to determine the specific components of dietary interventions that improve mental health, explore underlying mechanisms, and establish effective schemes for delivering these interventions in clinical and public health settings.

REGISTRATION

PROSPERO Online Protocol: CRD42018091256.

Mediterranean-style diet for the primary and secondary prevention of cardiovascular disease

BACKGROUND

The Seven Countries study in the 1960s showed that populations in the Mediterranean region experienced lower coronary heart disease (CHD) mortality probably as a result of different dietary patterns. Later observational studies have confirmed the benefits of adherence to a Mediterranean dietary pattern on cardiovascular disease (CVD) risk factors but clinical trial evidence is more limited.

OBJECTIVES

To determine the effectiveness of a Mediterranean-style diet for the primary and secondary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 9); MEDLINE (Ovid, 1946 to 25 September 2018); Embase (Ovid, 1980 to 2018 week 39); Web of Science Core Collection (Thomson Reuters, 1900 to 26 September 2018); DARE Issue 2 of 4, 2015 (Cochrane Library); HTA Issue 4 of 4, 2016 (Cochrane Library); NHS EED Issue 2 of 4, 2015 (Cochrane Library). We searched trial registers and applied no language restrictions.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) in healthy adults and adults at high risk of CVD (primary prevention) and those with established CVD (secondary prevention). Both of the following key components were required to reach our definition of a Mediterranean-style diet: high monounsaturated/saturated fat ratio (use of olive oil as main cooking ingredient and/or consumption of other traditional foods high in monounsaturated fats such as tree nuts) and a high intake of plant-based foods, including fruits, vegetables and legumes. Additional components included: low to moderate red wine consumption; high consumption of whole grains and cereals; low consumption of meat and meat products and increased consumption of fish; moderate consumption of milk and dairy products. The intervention could be dietary advice, provision of relevant foods, or both. The comparison group received either no intervention, minimal intervention, usual care or another dietary intervention. Outcomes included clinical events and CVD risk factors. We included only studies with follow-up periods of three months or more defined as the intervention period plus post intervention follow-up.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data and assessed risk of bias. We conducted four main comparisons:1. Mediterranean dietary intervention versus no intervention or minimal intervention for primary prevention;2. Mediterranean dietary intervention versus another dietary intervention for primary prevention;3. Mediterranean dietary intervention versus usual care for secondary prevention;4. Mediterranean dietary intervention versus another dietary intervention for secondary prevention.

MAIN RESULTS

In this substantive review update, 30 RCTs (49 papers) (12,461 participants randomised) and seven ongoing trials met our inclusion criteria. The majority of trials contributed to primary prevention: comparisons 1 (nine trials) and 2 (13 trials). Secondary prevention trials were included for comparison 3 (two trials) and comparison 4 (four trials plus an additional two trials that were excluded from the main analyses due to published concerns regarding the reliability of the data).Two trials reported on adverse events where these were absent or minor (low- to moderate-quality evidence). No trials reported on costs or health-related quality of life.Primary preventionThe included studies for comparison 1 did not report on clinical endpoints (CVD mortality, total mortality or non-fatal endpoints such as myocardial infarction or stroke). The PREDIMED trial (included in comparison 2) was retracted and re-analysed following concerns regarding randomisation at two of 11 sites. Low-quality evidence shows little or no effect of the PREDIMED (7747 randomised) intervention (advice to follow a Mediterranean diet plus supplemental extra-virgin olive oil or tree nuts) compared to a low-fat diet on CVD mortality (hazard ratio (HR) 0.81, 95% confidence interval (CI) 0.50 to 1.32) or total mortality (HR 1.0, 95% CI 0.81 to 1.24) over 4.8 years. There was, however, a reduction in the number of strokes with the PREDIMED intervention (HR 0.60, 95% CI 0.45 to 0.80), a decrease from 24/1000 to 14/1000 (95% CI 11 to 19), moderate-quality evidence). For CVD risk factors for comparison 1 there was low-quality evidence for a possible small reduction in total cholesterol (-0.16 mmol/L, 95% CI -0.32 to 0.00) and moderate-quality evidence for a reduction in systolic (-2.99 mmHg (95% CI -3.45 to -2.53) and diastolic blood pressure (-2.0 mmHg, 95% CI -2.29 to -1.71), with low or very low-quality evidence of little or no effect on LDL or HDL cholesterol or triglycerides. For comparison 2 there was moderate-quality evidence of a possible small reduction in LDL cholesterol (-0.15 mmol/L, 95% CI -0.27 to -0.02) and triglycerides (-0.09 mmol/L, 95% CI -0.16 to -0.01) with moderate or low-quality evidence of little or no effect on total or HDL cholesterol or blood pressure.Secondary preventionFor secondary prevention, the Lyon Diet Heart Study (comparison 3) examined the effect of advice to follow a Mediterranean diet and supplemental canola margarine compared to usual care in 605 CHD patients over 46 months and there was low-quality evidence of a reduction in adjusted estimates for CVD mortality (HR 0.35, 95% CI 0.15 to 0.82) and total mortality (HR 0.44, 95% CI 0.21 to 0.92) with the intervention. Only one small trial (101 participants) provided unadjusted estimates for composite clinical endpoints for comparison 4 (very low-quality evidence of uncertain effect). For comparison 3 there was low-quality evidence of little or no effect of a Mediterranean-style diet on lipid levels and very low-quality evidence for blood pressure. Similarly, for comparison 4 where only two trials contributed to the analyses there was low or very low-quality evidence of little or no effect of the intervention on lipid levels or blood pressure.

AUTHORS' CONCLUSIONS

Despite the relatively large number of studies included in this review, there is still some uncertainty regarding the effects of a Mediterranean-style diet on clinical endpoints and CVD risk factors for both primary and secondary prevention. The quality of evidence for the modest benefits on CVD risk factors in primary prevention is low or moderate, with a small number of studies reporting minimal harms. There is a paucity of evidence for secondary prevention. The ongoing studies may provide more certainty in the future.

The association between diet and mood: A systematic review of current literature

A number of studies have examined the association between diet and mood state, but the findings have been inconclusive. Herein, we conducted a systematic review to assess the association between different diet and mood state. PubMed, Cochrane's library, Science direct, Scopus, Google scholar and ISI web of science databases were searched for all available literature until December 2017 for studies assessing the association between diet and mood state. The Newcastle-Ottawa Scale and Jadad scale for reporting randomized clinical trials were used to assess study quality. A total of 18 studies out of 2857 met our inclusion criteria and included in our systematic review. Although there are not consistent findings between studies, it seems that DASH, vegetable-based, glycemic load-based, ketogenic and Paleo diets could improve mood more than the others. Further studies are needed to assess such relationship in a longer period to draw a firm link between diet and mood.

Effect of the Mediterranean diet on cognition and brain morphology and function: a systematic review of randomized controlled trials

Background

Observational studies of the Mediterranean diet suggest cognitive benefits, potentially reducing dementia risk.

Objective

We performed the first published review to our knowledge of randomized controlled trials (RCTs) investigating Mediterranean diet effects on cognition or brain morphology and function, with an additional focus on intervention diet quality and its relation to "traditional" Mediterranean dietary patterns.

Design

We searched 9 databases from inception (final update December 2017) for RCTs testing a Mediterranean compared with alternate diet for cognitive or brain morphology and function outcomes.

Results

Analyses were based on 66 cognitive tests and 1 brain function outcome from 5 included studies (n = 1888 participants). The prescribed Mediterranean diets varied considerably between studies, particularly with regards to quantitative food advice. Only 8/66 (12.1%) of individual cognitive outcomes at trial level significantly favored a Mediterranean diet for cognitive performance, with effect sizes (ESs) ranging from small (0.32) to large (1.66), whereas 2 outcomes favored controls. Data limitations precluded a meta-analysis. Of 8 domain composite cognitive scores from 2 studies, the 3 (Memory, Frontal, and Global function) from PREDIMED (PREvención con DIeta MEDiterránea) were significant, with ESs ranging from 0.39 to 1.29. A posttest comparison at a second PREDIMED site found that the Mediterranean diet modulates the effect of several genotypes associated with dementia risk for some cognitive outcomes, with mixed results. Finally, the risk of low-plasma brain-derived neurotrophic factor was reduced by 78% (OR = 0.22; 95% CI: 0.05, 0.90) in those who consumed a Mediterranean diet compared to control diet at 3 y in this trial. There was no benefit of the Mediterranean diet for incident cognitive impairment or dementia.

Conclusions

Five RCTs of the Mediterranean diet and cognition have been published to date. The data are mostly nonsignificant, with small ESs. However, the significant improvements in cognitive domain composites in the most robustly designed study warrant additional research.

Effects of Changing the Amount and Source of Dietary Carbohydrates on Symptoms and Dietary Satisfaction Over a 1-Year Period in Subjects with Type 2 Diabetes: Canadian Trial of Carbohydrates in Diabetes (CCD)

OBJECTIVES

To determine the long-term effects of changing the amount or source of dietary carbohydrate on quality of life (QOL), symptoms and dietary satisfaction in people with type 2 diabetes.

METHODS

Subjects with diabetes treated by diet alone (n=162) were randomly assigned to high-carbohydrate/high-glycemic-index (HGI) diets; high-carbohydrate/low-glycemic-index (LGI) diets; or lower-carbohydrate/high-monounsaturated-fat (LC) diets for 1 year. We measured QOL at baseline and at study's end, and we measured symptoms and dietary satisfaction quarterly.

RESULTS

The HGI, LGI and LC diets contained, respectively, 47±1, 52±1 and 40±1% energy carbohydrate; 30±1, 27±1 and 40±1% fat with GI 64±0.4, 55±0.4 and 59±0.4. Significantly more participants reported increased flatulence on LGI than on LC and HGI diets at 3 months (41%, 19%, 14%; p<0.05), but not at 12 months (29%, 17%, 17%; ns). Abdominal distension was more severe (46% vs. 14%, 19%; p<0.05), and headache less severe (8% vs. 22%, 23%; p<0.05) on LGI than on both other diets. Increased appetite was more severe on LC (33%) than on HGI diets (14%, p<0.05). Joint/limb pains were less severe on LGI (16%) than HGI (28%) diets. LC elicited more severe gloomy thoughts (23%) than LGI (4%; p<0.05) but greater dietary-satisfaction (70%; p<0.05) than LGI (40%) and HGI (48%) diets. For all diets, glycated hemoglobin (A1C) levels increased less in those who gained less weight, had less increased appetite and were more satisfied with the enjoyment obtained from eating.

CONCLUSIONS

Each diet elicited increased severity of 1 or more symptoms than the other diets. Although overall dietary satisfaction was greater on the 40% carbohydrate diet than on the 50% carbohydrate diet, the LGI diet was no less satisfying than the HGI diet. Changes in appetite and dietary satisfaction may influence body weight and glycemic control, or vice-versa.

Mediterranean Diet, Cognitive Function, and Dementia: A Systematic Review of the Evidence

A growing body of evidence suggests that adherence to the Mediterranean diet (MD) may protect against cognitive decline and dementia. Many epidemiologic studies and several randomized controlled trials (RCTs) have found positive effects of the MD on cognitive function, but findings remain inconsistent. The aim of this systematic review was to provide an update on the current knowledge of the effects of the MD on cognitive function, cognitive impairment, Alzheimer disease (AD), and all-type dementia. Five databases were searched-PubMed, Embase, CINAHL, CENTRAL, and PsycINFO (1806 to 25 May 2015)-with the use of prespecified criteria. Human studies that were published in English without any restriction on study type, population assessed, intervention period, follow-up time, or publication date, and that examined the association between adherence to the MD and cognitive function or dementia symptoms (as measured by cognitive function tests), were included. Only primary publication types were included. Thirty-two studies from 25 unique cohorts, including 5 RCTs and 27 observational studies, met the inclusion criteria. The majority of studies showed that the MD was associated with improved cognitive function, a decreased risk of cognitive impairment or decreased risk of dementia, or AD. Three studies found no correlation between the MD and AD, 3 further studies found no association between the MD and cognitive impairment, and 5 studies found no association between the MD and cognitive function. There was large heterogeneity, and studies differed with regard to quality. Based on the findings and the limitations in study design, we conclude that adherence to the MD is associated with better cognitive performance. However, it should be noted that the majority of findings come from epidemiologic studies that provide evidence for a correlation between the MD and cognition but not for a cause-and-effect relation. More controlled trials are required to establish a causational relation.

Mediterranean Diet and Health-Related Quality of Life in Two Cohorts of Community-Dwelling Older Adults

Introduction

In older adults, the Mediterranean diet is associated with lower risk of chronic diseases, but its association with health-related quality of life (HRQL) is still uncertain. This study assessed the association between the Mediterranean diet and HRQL in 2 prospective cohorts of individuals aged ≥60 years in Spain.

Methods

The UAM-cohort (n = 2376) was selected in 2000/2001 and followed-up through 2003. At baseline, diet was collected with a food frequency questionnaire, which was used to develop an 8-item index of Mediterranean diet (UAM-MDP). The Seniors-ENRICA cohort (n = 1911) was recruited in 2008/2010 and followed-up through 2012. At baseline, a diet history was used to obtain food consumption. Mediterranean diet adherence was measured with the PREDIMED score and the Trichopoulou’s Mediterranean Diet Score (MSD). HRQL was assessed, at baseline and at the end of follow-up, with the physical and mental component summaries (PCS and MCS) of the SF-36 questionnaire in the UAM-cohort, and the SF-12v.2 questionnaire in the Seniors-ENRICA cohort. Analyses were conducted with linear regression, and adjusted for the main confounders including baseline HRQL.

Results

In the UAM-cohort, no significant associations between the UAM-MDP and the PCS or the MCS were found. In the Seniors-ENRICA cohort, a higher PREDIMED score was associated with a slightly better PCS; when compared with the lowest tertile of PREDIMED score, the beta coefficient (95% confidence interval) for PCS was 0.55 (-0.48 to 1.59) in the second tertile, and 1.34 (0.21 to 2.47) in the highest tertile. However, the PREDIMED score was non-significantly associated with a better MCS score. The MSD did not show an association with either the PCS or the MCS.

Conclusions

No clinically relevant association was found between the Mediterranean diet and HRQL in older adults in Spain.

The impact of whole-of-diet interventions on depression and anxiety: a systematic review of randomised controlled trials

Objective

Non-pharmacological approaches to the treatment of depression and anxiety are of increasing importance, with emerging evidence supporting a role for lifestyle factors in the development of these disorders. Observational evidence supports a relationship between habitual diet quality and depression. Less is known about the causative effects of diet on mental health outcomes. Therefore a systematic review was undertaken of randomised controlled trials of dietary interventions that used depression and/or anxiety outcomes and sought to identify characteristics of programme success.

Design

A systematic search of the Cochrane, MEDLINE, EMBASE, CINAHL, PubMed and PyscInfo databases was conducted for articles published between April 1971 and May 2014.

Results

Of the 1274 articles identified, seventeen met eligibility criteria and were included. All reported depression outcomes and ten reported anxiety or total mood disturbance. Compared with a control condition, almost half (47 %) of the studies observed significant effects on depression scores in favour of the treatment group. The remaining studies reported a null effect. Effective dietary interventions were based on a single delivery mode, employed a dietitian and were less likely to recommend reducing red meat intake, select leaner meat products or follow a low-cholesterol diet.

Conclusions

Although there was a high level of heterogeneity, we found some evidence for dietary interventions improving depression outcomes. However, as only one trial specifically investigated the impact of a dietary intervention in individuals with clinical depression, appropriately powered trials that examine the effects of dietary improvement on mental health outcomes in those with clinical disorders are required.

Lipid correlates of attentional impulsivity in first episode mania: results from an Indian population

BACKGROUND

Attentional/cognitive impulsivity has been demonstrated as being associated with an increased risk for suicide and other self-harming behaviors, along with a more severe course in patients with bipolar disorder. That an alteration of the various serum lipid fractions might be associated with increased impulsivity has been proposed in the past, but evidences are ambiguous and mainly based on western population data.

OBJECTIVE

The present study was aimed to analyze the attentional impulsivity and various serum lipid fractions in bipolar patients, from an Indian perspective.

MATERIALS AND METHODS

At presentation, 60 drug free/naïve first episode Mania patients were rated on the Barratt impulsiveness scale-version 11 and Young Mania Rating Scale; body mass index (BMI) was calculated and blood samples were analyzed for total cholesterol (TC), high density lipoproteins, low density lipoproteins and very low density lipoproteins (VLDL), triglycerides (TG) and apolipoproteins A1 and B.

RESULTS

The analysis revealed statistically significant negative correlation and inverse linear relationship between TC, TG, VLDL and BMI with attentional impulsivity.

CONCLUSION

The present study adds to the growing literature on a complex relationship between lipid fractions and attentional impulsivity. The findings present interesting insights into the possible substrates of human behavior at biochemical levels. The implications are many, including a need to introspect regarding the promotion of weight loss and cholesterol reduction programs in constitutionally vulnerable population.

The potential role of fruit and vegetables in aspects of psychological well-being: a review of the literature and future directions

The objective of the present paper was to review the literature investigating the potential relationship between fruit and vegetables (FV) and psychological well-being. The rising prevalence of mental ill health is causing considerable societal burden. Inexpensive and effective strategies are therefore required to improve the psychological well-being of the population, and to reduce the negative impact of mental health problems. A growing body of literature suggests that dietary intake may have the potential to influence psychological well-being. For example, studies have suggested that particular dietary constituents, including vitamins and minerals, might be beneficial to psychological health. However, in order to better reflect normal dietary intake, health-based research has increasingly begun to focus on whole foods and dietary patterns, rather than individual nutrients. One food group that has received increasing attention with regard to psychological health is FV. This is probably a result of the strong evidence base, which exists in relation to their protective association with a number of chronic diseases, as well as the fact that they are a rich source of some of the nutrients which have been linked to psychological health. While some promising findings exist with regards to FV intake and psychological well-being, overall, results are inconsistent. Possible reasons for this, such as methodological issues related to study design and the measurement of psychological well-being and FV intake, are discussed within this review. Based on the predominantly observational nature of existing literature, the present paper concludes that future well-designed randomised controlled trials are required to investigate the relationship further.

'Mediterranean' dietary pattern for the primary prevention of cardiovascular disease

BACKGROUND

The Seven Countries study in the 1960s showed that populations in the Mediterranean region experienced lower cardiovascular disease (CVD) mortality probably as a result of different dietary patterns. Later observational studies have confirmed the benefits of adherence to a Mediterranean dietary pattern on CVD risk factors. Clinical trial evidence is limited, and is mostly in secondary prevention.

OBJECTIVES

To determine the effectiveness of a Mediterranean dietary pattern for the primary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 9 of 12, September 2012); MEDLINE (Ovid, 1946 to October week 1 2012); EMBASE (Ovid, 1980 to 2012 week 41); ISI Web of Science (1970 to 16 October 2012); Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment Database and Health Economics Evaluations Database (Issue 3 of 12, September 2012). We searched trial registers and reference lists of reviews and applied no language restrictions.

SELECTION CRITERIA

We selected randomised controlled trials in healthy adults and adults at high risk of CVD. A Mediterranean dietary pattern was defined as comprising at least two of the following components: (1) high monounsaturated/saturated fat ratio, (2) low to moderate red wine consumption, (3) high consumption of legumes, (4) high consumption of grains and cereals, (5) high consumption of fruits and vegetables, (6) low consumption of meat and meat products and increased consumption of fish, and (7) moderate consumption of milk and dairy products. The comparison group received either no intervention or minimal intervention. Outcomes included clinical events and CVD risk factors.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and contacted chief investigators to request additional relevant information.

MAIN RESULTS

We included 11 trials (15 papers) (52,044 participants randomised). Trials were heterogeneous in the participants recruited, in the number of dietary components and follow-up periods. Seven trials described the intervention as a Mediterranean diet. Clinical events were reported in only one trial (Women's Health Initiative 48,835 postmenopausal women, intervention not described as a Mediterranean diet but increased fruit and vegetable and cereal intake) where no statistically significant effects of the intervention were seen on fatal and non-fatal endpoints at eight years. Small reductions in total cholesterol (-0.16 mmol/L, 95% confidence interval (CI) -0.26 to -0.06; random-effects model) and low-density lipoprotein (LDL) cholesterol (-0.07 mmol/L, 95% CI -0.13 to -0.01) were seen with the intervention. Subgroup analyses revealed statistically significant greater reductions in total cholesterol in those trials describing the intervention as a Mediterranean diet (-0.23 mmol/L, 95% CI -0.27 to -0.2) compared with control (-0.06 mmol/L, 95% CI -0.13 to 0.01). Heterogeneity precluded meta-analyses for other outcomes. Reductions in blood pressure were seen in three of five trials reporting this outcome. None of the trials reported adverse events.

AUTHORS' CONCLUSIONS

The limited evidence to date suggests some favourable effects on cardiovascular risk factors. More comprehensive interventions describing themselves as the Mediterranean diet may produce more beneficial effects on lipid levels than those interventions with fewer dietary components. More trials are needed to examine the impact of heterogeneity of both participants and the intervention on outcomes.

Prevention of post-stroke cognitive decline: a review focusing on lifestyle interventions

BACKGROUND AND PURPOSE

Despite a high prevalence of post-stroke cognitive impairment, therapeutic possibilities are still limited. Stroke and dementia share the same cluster of modifiable risk factors. Thus, lifestyle interventions and strict adherence to medication may not only decrease the risk of recurrent stroke but also the risk of post-stroke cognitive decline.

METHODS

We performed a systematic literature search for randomized clinical trials (RCTs) targeting modifiable risk factors for the prevention of cognitive decline following stroke.

RESULTS

We identified 25 non-pharmacological interventions and eight multiple risk factor interventions in stroke patients using cognition as outcome measure. None of the published trials investigated interventions aimed at the prevention of post-stroke cognitive decline. However, a number of ongoing trials aim at risk factor reduction and include measures on cognition.

CONCLUSION

Evidence for risk factor modification for the prevention of cognitive decline after stroke is scarce and comes mainly from observational studies. There is a need for more RCTs targeting the prevention of post-stroke dementia using lifestyle interventions and a multiple risk factor approach.

Intentional weight loss and changes in symptoms of depression: a systematic review and meta-analysis

OBJECTIVE

Obesity is related to increased risk of several health complications, including depression. Many studies have reported improvements in mood with weight loss, but results have been equivocal. The present meta-analysis examined changes in symptoms of depression that were reported in trials of weight loss interventions. Between-groups comparisons of different weight loss methods (for example, lifestyle modification, diet-alone and pharmacotherapy) were examined, as were within-group changes for each treatment type.

METHOD

MEDLINE was searched for articles published between 1950 and January 2009. Several obesity-related terms were intersected with terms related to depression. Results were filtered to return only studies of human subjects, published in English. Of 5971 articles, 394 were randomized controlled trials. Articles were excluded if they did not report mean changes in weight or symptoms of depression, included children or persons with psychiatric disorders (other than depression), or provided insufficient data for analysis. Thirty-one studies (n=7937) were included. Two authors independently extracted a description of each study treatment, sample characteristics, assessment methods and changes in weight and symptoms of depression. Treatments were categorized as lifestyle modification, non-dieting, dietary counseling, diet-alone, exercise-alone, pharmacotherapy, placebo or control interventions.

RESULTS

Random effects models found that lifestyle modification was superior to control and non-dieting interventions for reducing symptoms of depression, and marginally better than dietary counseling and exercise-alone programs. Exercise-alone programs were superior to controls. No differences were found for comparisons of pharmacologic agents and placebos. Within-group analyses found significant reductions in symptoms of depression for nearly all active interventions. A meta-regression found no relationship between changes in weight and changes in symptoms of depression in lifestyle modification interventions.

CONCLUSIONS

On average, obese individuals in weight loss trials experienced reductions in symptoms of depression. Future studies should examine incidence and resolution of clinically significant depressive disorders with weight loss interventions.

Cholesterol and cognition in schizophrenia: a double-blind study of patients randomized to clozapine, olanzapine and haloperidol

OBJECTIVE

A positive relationship between cholesterol levels and cognition has been reported in various human and animal studies, but has never been investigated in schizophrenia. The goal of this study was to examine this relationship in schizophrenic patients randomized to clozapine, olanzapine or haloperidol.

METHOD

This was a double-blind randomized prospective 12-week study. Participants received a baseline evaluation including a cognitive battery consisting of an evaluation of psychomotor function, general executive function, visual and verbal memory, and visuospatial ability. Their fasting serum cholesterol level was also assessed. The participants were then randomized to clozapine, olanzapine, or haloperidol. They were evaluated at the end of 12 weeks. A general cognitive index (GCI) derived from the cognitive battery was the primary variable.

RESULTS

82 patients had both baseline and endpoint neurocognitive assessments and cholesterol levels. There was a statistically and clinically significant positive association between change in cholesterol levels and change in GCI. This association was especially pronounced for verbal memory. There was no interaction between medication grouping and cholesterol level; the positive association was observable separately in each medication group. It was very robust and remained significant after we controlled for glucose and triglyceride levels, anticholinergic side effects, medication serum levels, cholesterol lowering medications, and pre-study antipsychotic medications.

CONCLUSIONS

Cholesterol levels show a strong association with cognition in schizophrenia in all medication groups. Further research on the role of lipid metabolism in cognition may suggest new treatments for this core deficit of schizophrenia.

Low cholesterol is a risk factor for attentional impulsivity in patients with mood symptoms

This study examined the relationship between cholesterol levels and impulsivity in a large sample of patients with mood symptoms. Three hundred and one patients with mood, anxiety, and personality disorders completed a battery of psychometric scales including the Barratt Impulsiveness Scale-Version 11 (BIS-11) and the Profile of Mood States (POMS). On the same day of psychometric assessment, blood samples were analyzed for total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C). Statistical analysis controlling for the confounding effects of age, gender, diagnosis, and current mood symptoms showed that lower TC levels were associated with increased attentional impulsivity. There was a weak linear correlation between TC and attentional impulsivity across the entire range of TC levels (110-295mg/dL) but a highly significant difference between participants with TC levels lower than 165mg/dL and the rest of the sample. The current study adds to the growing body of evidence pointing to the association between serum cholesterol and mental health. Considering that attentional impulsivity is a demonstrated risk factor for suicide, patients presenting with low cholesterol and mood symptoms may warrant increased clinical attention and surveillance.

Statins reduce the neurofibrillary tangle burden in a mouse model of tauopathy

Statin treatment has been associated with a reduced risk of Alzheimer disease and decreased amyloid deposition in mouse models. No animal studies have reported effects of statins on tau aggregates and neurofibrillary tangles (NFTs), the pathological hallmarks of Alzheimer disease that correlate with dementia. We investigated the effect of statins on NFTs in a transgenic mouse tauopathy model and found the following: 1) 1-month treatment with the blood-brain barrier-permeable agent simvastatin in normocholesterolemic aged mice significantly reduced the NFT burden and decreased lectin-positive microglia; 2) simvastatin significantly decreased NFTs and improved T-maze performance in young animals treated for 8 months; 3) treatment of hypercholesterolemic mice for 5 months with blood-brain barrier-impermeable atorvastatin markedly reduced the NFT burden and decreased lectin-positive microglia; 4) nonstatin cholesterol-lowering strategies showed a modest NFT decrease compared with statin treatment; and 5) there was a positive correlation between microglial and NFT burden (r = 0.8). Together, these results suggest that statins reduce NFT burden irrespective of blood-brain barrier permeability at both early and late ages in long- and short-term treatment paradigms and under normocholesterolemic and hypercholesterolemic conditions. The decrease in microglia, coupled with the limited effect of nonstatin cholesterol lowering, suggests that the anti-NFT effect of statins may be related to their anti-inflammatory and not necessarily to their cholesterol-lowering properties. Statins may provide therapy against NFTs in tauopathies, particularly when NFTs are the major neuropathologic component.

Functional relationships between serum total cholesterol levels, executive control, and sustained attention

This study investigated the potential relationship between serum total cholesterol (TC) and two specific aspects of cognition (executive control and sustained attention) in a non-elderly sample, after controlling for life stress and several sociodemographic and health variables. For each participant (n = 46), measurements of TC, physical health, and life stress were obtained, and executive control and sustained attention were assessed using the Tower of London and the Digit Vigilance Test. The outcomes of these cognitive assessments were correlated with TC, and a covariate-adjusted analysis was performed. After controlling for several co-variates, TC was found to be significantly negatively associated with components of executive control and sustained attention. Because these cognitive functions are crucial in the moment-to-moment regulation of behavior, elevated TC may have negative behavioral consequences in everyday life situations.

Adherence to the Mediterranean diet is associated with better mental and physical health

The aim of the present study was to analyse the association between adherence to the Mediterranean diet and self-perceived mental and physical health function, controlled for confounding effects of age, smoking, BMI, alcohol consumption, educational level, leisure-time physical activity and the presence of chronic conditions. A random sample of the 35-74-year-old population (3910 men and 4285 women) of Gerona, Spain, was examined in 2000 and 2005 in two independent population-based cross-sectional surveys. Dietary intake was assessed using a validated FFQ. The Mediterranean diet score (MDS) was calculated according to tertile distribution of energy-adjusted food consumption considered characteristic for the Mediterranean region. Health-related quality of life was measured using the SF-12 questionnaire. Alcohol consumption, leisure-time physical activity and smoking habits were recorded. Weight and height were measured. Age-adjusted linear regression analysis revealed a significant (P < 0.01) direct association of the MDS with self-reported mental and physical health in both sexes. An increase of 5 units of the MDS was directly associated with changes of 0.74 and 1.15 units in men and women, respectively, in the mental component score after controlling for potential confounders. The age-adjusted direct association of the MDS with self-reported scoring of physical health remained stable after adjusting for several confounders in men but was attenuated in women. Adherence to the Mediterranean diet was associated with higher scoring for self-perceived health.

Potential therapeutic role of statins in neurological disorders

Statins, the inhibitors of HMG-CoA reductase, are currently among the most commonly prescribed agents for the prevention of cardiovascular disease. It is well established that statins reduce cholesterol levels and prevent coronary heart disease. Moreover, evidence suggests that statins have additional properties such as endothelial protection via actions on the nitric oxide synthetase system as well as antioxidant, anti-inflammatory and antiplatelet effects. There is evidence that all these actions might have potential therapeutic implications not only in stroke, but also in various neurological disorders, such as Alzheimer's disease, Parkinson's disease, multiple sclerosis and primary brain tumors. In this review, we summarize the protective effects of statins on various neurological diseases. Currently available data suggest that statins are safe and effective in the treatment of these neurological disorders, although further experiments and new data are required.

Dietary electrolytes are related to mood

Dietary therapies are routinely recommended to reduce disease risk; however, there is concern they may adversely affect mood. We compared the effect on mood of a low-sodium, high-potassium diet (LNAHK) and a high-calcium diet (HC) with a moderate-sodium, high-potassium, high-calcium Dietary Approaches to Stop Hypertension (DASH)-type diet (OD). We also assessed the relationship between dietary electrolytes and cortisol, a stress hormone and marker of hypothalamic-pituitary-adrenal (HPA) axis activity. In a crossover design, subjects were randomized to two diets for 4 weeks, the OD and either LNAHK or HC, each preceded by a 2-week control diet (CD). Dietary compliance was assessed by 24 h urine collections. Mood was measured weekly by the Profile of Mood States (POMS). Saliva samples were collected to measure cortisol. The change in mood between the preceding CD and the test diet (LNAHK or HC) was compared with the change between the CD and OD. Of the thirty-eight women and fifty-six men (mean age 56.3 (sem 9.8) years) that completed the OD, forty-three completed the LNAHK and forty-eight the HC. There was a greater improvement in depression, tension, vigour and the POMS global score for the LNAHK diet compared to OD (P < 0.05). Higher cortisol levels were weakly associated with greater vigour, lower fatigue, and higher levels of urinary potassium and magnesium (r 0.1-0.2, P < 0.05 for all). In conclusion, a LNAHK diet appeared to have a positive effect on overall mood.