Graham Mazereeuw

Effects of omega-3 fatty acids on cognitive performance: a meta-analysis

BACKGROUND Higher intake of omega-3 fatty acids (n-3 FAs) is associated with a reduced risk of Alzheimers disease (AD) and milder forms of cognitive impairment (e.g. cognitive impairment no dementia [CIND]); however, findings from interventional trials are inconsistent. This meta-analysis examined the neuropsychological benefit of n-3 FAs in randomized double-blind placebo-controlled studies (RCTs) including healthy, CIND, or AD subjects. METHODS Literature was searched using Medline, Embase, PsycInfo, Cochrane Library, Allied and Complementary Medicine Database (AMED), and Cumulative Index to Nursing and Allied Health Literature (CINAHL) up to September 2011. Treatment effects were summarized across cognitive subdomains, and effect sizes were estimated using Hedges g and random effects modeling. RESULTS Ten RCTs were combined quantitatively. There was no effect of n-3 FAs on composite memory (g = 0.04 [95% CI: -0.06-0.14], N = 934/812, p = 0.452). When examined by domain, no overall benefit for immediate recall (0.04 [-0.05-0.13], N = 934/812, p = 0.358) was detected; however, an effect in CIND subjects (0.16 [0.01-0.31], N = 349/327, p = 0.034) was found. A benefit for attention and processing speed was also detected in CIND (0.30 [0.02-0.57], N = 107/86, p = 0.035), but not healthy subjects. Benefits for delayed recall, recognition memory, or working memory and executive function were not observed. Treatment did not benefit AD patients as measured by the Mini-Mental State Examination (MMSE) or Alzheimers Disease Assessment Scale-Cognitive Subscale (ADAS-cog). No differences in adverse events (AE), dropout, or dropout due to AE between groups were observed. CONCLUSIONS These results suggest an effect of n-3 FAs within specific cognitive domains in CIND, but not in healthy or AD subjects.

Zinc in Depression: A Meta-Analysis

BACKGROUND Zinc is an essential micronutrient with diverse biological roles in cell growth, apoptosis and metabolism, and in the regulation of endocrine, immune, and neuronal functions implicated in the pathophysiology of depression. This study sought to quantitatively summarize the clinical data comparing peripheral blood zinc concentrations between depressed and nondepressed subjects. METHODS PubMed, Cumulated Index to Nursing and Allied Health Literature, and PsycINFO were searched for original peer-reviewed studies (to June 2012) measuring zinc concentrations in serum or plasma from depressed subjects (identified by either screening or clinical criteria) and nondepressed control subjects. Mean (±SD) zinc concentrations were extracted, combined quantitatively in random-effects meta-analysis, and summarized as a weighted mean difference (WMD). RESULTS Seventeen studies, measuring peripheral blood zinc concentrations in 1643 depressed and 804 control subjects, were included. Zinc concentrations were approximately -1.85 µmol/L lower in depressed subjects than control subjects (95% confidence interval: [CI]: -2.51 to -1.19 µmol/L, Z17 = 5.45, p < .00001). Heterogeneity was detected (χ(2)17 = 142.81, p < .00001, I(2) = 88%) and explored; in studies that quantified depressive symptoms, greater depression severity was associated with greater relative zinc deficiency (B = -1.503, t9 = -2.82, p = .026). Effect sizes were numerically larger in studies of inpatients (WMD -2.543, 95% CI: -3.522 to -1.564, Z9 = 5.09, p < .0001) versus community samples (WMD -.943, 95% CI: -1.563 to -.323, Z7 = 2.98, p = .003) and in studies of higher methodological quality (WMD -2.354, 95% CI: -2.901 to -1.807, Z7 = 8.43, p < .0001). CONCLUSIONS Depression is associated with a lower concentration of zinc in peripheral blood. The pathophysiological relationships between zinc status and depression, and the potential benefits of zinc supplementation in depressed patients, warrant further investigation.

Potential roles of zinc in the pathophysiology and treatment of major depressive disorder

Incomplete response to monoaminergic antidepressants in major depressive disorder (MDD), and the phenomenon of neuroprogression, suggests a need for additional pathophysiological markers and pharmacological targets. Neuronal zinc is concentrated exclusively within glutamatergic neurons, acting as an allosteric modulator of the N-methyl D-aspartate and other receptors that regulate excitatory neurotransmission and neuroplasticity. Zinc-containing neurons form extensive associational circuitry throughout the cortex, amygdala and hippocampus, which subserve mood regulation and cognitive functions. In animal models of depression, zinc is reduced in these circuits, zinc treatment has antidepressant-like effects and dietary zinc insufficiency induces depressive behaviors. Clinically, serum zinc is lower in MDD, which may constitute a state-marker of illness and a risk factor for treatment-resistance. Marginal zinc deficiency in MDD may relate to multiple putative mechanisms underlying core symptomatology and neuroprogression (e.g. immune dysfunction, monoamine metabolism, stress response dysregulation, oxidative/nitrosative stress, neurotrophic deficits, transcriptional/epigenetic regulation of neural networks). Initial randomized trials suggest a benefit of zinc supplementation. In summary, molecular and animal behavioral data support the clinical significance of zinc in the setting of MDD.

Exercise intervention and inflammatory markers in coronary artery disease: A meta-analysis

BACKGROUND Inflammatory activity plays a role in the development and progression of coronary artery disease (CAD), and exercise confers survival benefit. We performed a meta-analysis of changes in inflammatory biomarkers over the course of exercise interventions in patients with CAD. METHODS We searched MEDLINE, Embase, the Cochrane Collaboration, AMED, and CINAHL for studies reporting peripheral inflammatory biomarker concentrations before and after exercise interventions of ≥ 2 weeks in patients with CAD. Data were summarized using standard mean differences (SMD) and 95% CIs. RESULTS Twenty-three studies were included. Concentrations of C-reactive protein (CRP; SMD -0.345, 95% CI -0.444 to -0.246, n = 1,466, P < .001), interleukin 6 (SMD -0.546, 95% CI -0.739 to -0.353, n = 280, P < .001), fibrinogen (SMD -0.638, 95% CI -0.953 to -0.323, n = 247, P < .001), and vascular cell adhesion molecule 1 (SMD -0.413, 95% CI -0.778 to -0.048, n = 187, P = .027) were lower postintervention. Higher total cholesterol (B = -0.328, 95% CI -0.612 to -0.043, P = .026) and higher total/high-density lipoprotein cholesterol ratios (B = -0.250, 95% CI -0.425 to -0.076, P = .008) at baseline were associated with greater reductions in CRP. In controlled studies, follow-up concentrations of CRP (SMD -0.500, 95% CI -0.844 to -0.157, n(exercise/control) = 485/284, P = .004), and fibrinogen (SMD -0.544, 95% CI -1.058 to -0.030, n(exercise/control) = 148/100, P = .038) were lower in subjects who exercised compared with controls. CONCLUSION Exercise training is associated with reduced inflammatory activity in patients with CAD. C-reactive protein and fibrinogen have provided the strongest evidence. Higher baseline CRP and adverse baseline lipid profiles predicted greater reductions in CRP.

Platelet activating factors in depression and coronary artery disease: A potential biomarker related to inflammatory mechanisms and neurodegeneration

The persistence of a depressive episode in coronary artery disease (CAD) patients not only heightens the risk of acute ischemic events, but it is also associated with accelerated cognitive decline. Antidepressant interventions for depression in CAD have only modest effects and novel approaches are limited by a poor understanding of etiological mechanisms. This review proposes that the platelet activating factor (PAF) family of lipids might be associated with the persistence of a depressive episode and related neurodegenerative pathology in CAD due to their association with leading etiological mechanisms for depression in CAD such as inflammation, oxidative and nitrosative stress, vascular endothelial dysfunction, and platelet reactivity. The evidence implicating PAFs in CAD, vascular pathology, and neurodegenerative processes is also presented. We also propose future directions for the investigation of PAFs as mediators of persistent depression. In summary, PAFs are implicated in leading mechanisms associated with depression in CAD. PAFs may therefore be associated with the persistence of depression in CAD and related to neurodegenerative and cognitive sequelae.

Cholinesterase Inhibitor Discontinuation in Patients With Alzheimer’s Disease: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVE This meta-analysis examined the effects of cholinesterase inhibitor (ChEI) discontinuation in patients with Alzheimers disease (AD). DATA SOURCES Electronic records up to March 2014 were searched from MEDLINE, Embase, PsycINFO, Cochrane Library, Allied and Complementary Medicine Database, and Cumulative Index to Nursing and Allied Health Literature. Search terms included Alzheimers disease and cholinesterase inhibitors, plus discontinuation or cessation or tapering or withdrawal. There were no language limits. STUDY SELECTION Randomized, double-blind, placebo-controlled studies investigating the effect of ChEI discontinuation on patients with AD according to standardized criteria (eg, National Institute of Neurologic and Communicative Disorders and Stroke/Alzheimers Disease and Related Disorders Association, DSM-IV) and presenting measurable results of neuropsychological testing were included. DATA EXTRACTION Demographics, setting, ChEI treatment length, discontinuation protocol, follow-up duration, study outcomes, and dropouts during the double-blind phase were extracted. RESULTS Of 1,430 records returned, 18 were reviewed. Five ChEI discontinuation randomized controlled trials (N = 321 continued and N = 332 discontinued, following patients for 1.5-24 months) were analyzed. Discontinued patients demonstrated a significant worsening of cognition (standard mean Mini-Mental State Examination difference: -0.29 [95% CI, -0.45 to -0.13], N = 300 continued/307 discontinued, P < .001), a significant worsening of neuropsychiatric symptoms (standard mean Neuropsychiatric Inventory difference: -0.32 [-0.51 to -0.12], N = 199/211, P = .001), and significantly higher dropout rates (risk ratio [RR] = 1.33 [1.11-1.59], N = 321/332, P = .002) compared to those who continued. No difference in adverse events was observed (RR = 1.01 [0.85-1.20], N = 314/326, P = .92). CONCLUSIONS ChEI discontinuation may have negative effects on cognition and neuropsychiatric symptoms, a finding corroborated by a higher incidence of trial dropout.

A meta-analysis of lipid peroxidation markers in major depression.

Background Major depressive disorder (MDD) may be associated with oxidative damage to lipids, which can potentially affect mood-regulating pathways. This meta-analysis summarizes current knowledge regarding lipid peroxidation markers in clinical samples of MDD and the effects of antidepressant pharmacotherapy on those markers. Methods MEDLINE, EMBASE, CINAHL, PsycINFO, and Cochrane Collaboration were searched for original, peer-reviewed articles measuring markers of lipid peroxidation in patients with MDD and nondepressed healthy controls up to April 2015. Standardized mean differences (SMDs) were generated from random effects models summarizing mean (± standard deviations) concentrations of selected markers. Results Lipid peroxidation was greater in MDD than in controls (studies =17, N=857 MDD/782 control, SMD =0.83 [0.56–1.09], z=6.11, P<0.01, I2=84.0%) and was correlated with greater depressive symptom severity (B=0.05, df=8, P<0.01). Antidepressant treatment was associated with a reduction in lipid peroxidation in MDD patients (studies=5, N=222, SMD=0.71 [0.40–0.97], P<0.01; I2=42.5%). Limitations Lipid peroxidation markers were sampled from peripheral blood, included studies comparing MDD to controls were all cross-sectional, and only five antidepressant treatment studies were eligible for inclusion. Conclusion Increased lipid peroxidation was associated with MDD and may be normalized by antidepressants. Continued investigation of lipid peroxidation in MDD is warranted.

Platelet activating factors are associated with depressive symptoms in coronary artery disease patients: a hypothesis-generating study

Introduction Depression is a frequent complication of coronary artery disease (CAD) with an unknown etiology. Platelet activating factor (PAF) lipids, which are associated with CAD, have recently been linked with novel proposed etiopathological mechanisms for depression such as inflammation, oxidative/nitrosative stress, and vascular endothelial dysfunction. Methods and results This hypothesis-generating study investigated the relationships between various PAF species and depressive symptoms in 26 CAD patients (age: 60.6±9.2 years, 69% male, mean Hamilton Depression Rating Scale [HAM-D] score: 11.8±5.2, HAM-D range: 3–20). Plasma PAF analyses were performed using high performance liquid chromatography electrospray ionization mass spectrometry in precursor ion scan. Significant associations between depressive symptom severity (HAM-D score) and a greater plasma abundance of the PAFs phosphocholine (PC) PC(O-12:0/2:0) (r=0.49, P=0.01), PC(O-14:1/2:0) (r=0.43, P=0.03), PC(O-17:3/2:0) (r=0.44, P=0.04), and PC(O-18:3/2:0) (r=0.50, P=0.01) were observed. Associations between those PAFs and HAM-D score persisted after adjusting for age and sex. Conclusion These preliminary findings support the exploration of the PAF lipidome for depressive symptom biomarkers in CAD patients. Patients were recruited as part of the following clinical trial: NCT00981383.

Omega-3 Fatty Acids, Depressive Symptoms, and Cognitive Performance in Patients With Coronary Artery Disease: Analyses From a Randomized, Double-Blind, Placebo-Controlled Trial.

Abstract This trial investigated the efficacy of omega-3 polyunsaturated fatty acid (n-3 PUFA) treatment for improving depressive symptoms and cognitive performance in patients with coronary artery disease (CAD) participating in cardiac rehabilitation. Patients with CAD aged 45 to 80 years were randomized to receive either 1.9-g/d n-3 PUFA treatment or placebo for 12 weeks. Depressive symptoms were measured using the Hamilton Depression Rating Scale (HAM-D, primary outcome) and the Beck Depression Inventory II (BDI-II). Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria were used to identify a depressive episode at baseline. Cognitive performance was measured using a standardized battery for vascular cognitive impairment. In 92 patients (age, 61.7 ± 8.7 y; 76% male, 40% depressed; HAM-D, 6.9 ± 5.9; BDI-II, 12.3 ± 10.9; n = 45 n-3 PUFA, n = 47 placebo), depression decreased (HAM-D, F3,91 = 2.71 and P = 0.049; BDI-II, F3,91 = 6.24 and P < 0.01), and cognitive performance improved (attention/processing speed, F1,91 = 5.57, P = 0.02; executive function, F1,91 = 14.64, P < 0.01; visuospatial memory, F1,91 = 4.01, P = 0.04) over cardiac rehabilitation. Omega-3 PUFA treatment increased plasma eicosapentaenoic acid (F1,29 = 33.29, P < 0.01) and docosahexaenoic acid (F1,29 = 15.29, P < 0.01) concentrations but did not reduce HAM-D (F3,91 = 1.59, P = 0.20) or BDI-II (F3,91 = 0.46, P = 0.50) scores compared with placebo. Treatment did not improve cognitive performance; however, n-3 PUFAs significantly increased verbal memory compared with placebo in a subgroup of nondepressed patients (F1,54 = 4.16, P = 0.04). This trial suggests that n-3 PUFAs do not improve depressive and associated cognitive symptoms in those with CAD. The possible benefits of n-3 PUFAs for verbal memory may warrant investigation in well-powered studies.

Platelet-activating factors are associated with cognitive deficits in depressed coronary artery disease patients: a hypothesis-generating study

BackgroundPatients with coronary artery disease (CAD) are at risk of accelerated cognitive decline, particularly those with major depression. Mechanisms for cognitive deficits associated with CAD, and the effects of depression, remain poorly understood. However, CAD is associated with inflammatory processes that have been linked to neurodegeneration, may contribute to cognitive decline, and are elevated in depression. Platelet-activating factors (PAFs) are emerging as key lipid mediators that may be central to those processes and highly relevant to cognitive decline in CAD.MethodsThis cross-sectional study investigated relationships between various PAFs and cognitive performance in 24 patients with CAD (age, 60.3 ± 9.4; 70.8% male). Analyses were repeated in a subgroup of 15 patients with CAD with major depression (DSM-IV). Cognitive performance was assessed using a standardized battery and summary z scores were calculated based on age, sex, and education norms. Global cognitive performance was the average of domain-specific z scores. Plasma PAF analyses were performed using electrospray ionization mass spectrometry (precursor ion scan).ResultsA greater abundance of PAF PC(O-18:0/2:0) was associated with poorer global cognitive performance in patients with CAD (r = -0.45, P = 0.03). In the major depressed subgroup, PAF PC(O-18:0/2:0) (r = -0.59, P = 0.02) as well as PC(O-16:0/2:0) (r = -0.52, P = 0.04), and lyso-PAF PC(O-16:0/0:0) (r = -0.53, P = 0.04) were associated with poorer global cognitive performance. A greater abundance of PAF PC(O-19:5/2:0) was associated with better global cognitive performance (r = 0.55, P = 0.03), suggesting a possible compensatory species.ConclusionsThis study suggests that certain PAFs might be associated with global cognitive performance in patients with CAD, with stronger relationships observed in those with major depression. Confirmation of these preliminary findings is warranted.