Do informant-reported subjective cognitive complaints predict progression to mild cognitive impairment and dementia better than self-reported complaints in old adults? A meta-analytical study

BackgroundSubjective cognitive complaints (SCCs) are considered a risk factor for objective cognitive decline and conversion to dementia. The aim of this study was to determine whether self-reported or informant-reported SCCs best predict progression to mild cognitive impairment (MCI) and/or dementia.MethodsWe reviewed prospective longitudinal studies of Cognitively Unimpaired (CU) older adults with self-reported and informant-reported SCCs at baseline, assessed by questions or questionnaires that considered the transition to MCI and/or dementia. A random-effects meta-analysis was performed to obtain pooled estimates and 95% CIs.ResultsBoth self-reported and informant-reported SCCs are associated with an elevated risk of transition from CU to MCI and/or dementia. The association appears stronger and more robust for informant-reported data [1.38, with a 95% CI of 1.16 –1.64, p < 0.001] than for self-reported data [1.27 (95% CI 1.06 – 1.534, p = 0.011].ConclusionsOur results suggest that corroborated information from one informant could provide important details for distinguishing between normal aging and clinical states.     

Effects of virtual reality combined cognitive and physical interventions on cognitive function in older adults with mild cognitive impairment: A systematic review and meta-analysis

ObjectiveCombined cognitive and physical interventions based on virtual reality may help delay the progression of MCI to dementia or prevent dementia. However, their efficacy is less well studied compared to pharmaceutical treatments. The purpose of this review was to evaluate the effects of cognitive and physical interventions based on virtual reality on cognitive function (global cognition, memory or executive function/attention) of older adults with mild cognitive impairment.MethodsWe searched the PubMed, Web of Science, Scopus, Embase, Cochrane Library, PsycINFO, CINAHL and IEEE from inception to 13 May 2021. Only randomized controlled trials which incorporated virtual reality cognitive and physical components targeted to individuals with mild cognitive impairment were eligible. Two researchers independently conducted document retrieval, study selection, data extraction, and methodological quality evaluation.Result7 randomized controlled trials were included in a total of 8 articles. No studies were rated as having a "high" risk of overall bias. The results of a meta-analysis showed that VR combined cognitive and physical interventions enhanced the global cognitive (MD = 2.66, 95% CI = 1.79–3.54, P = 0.03, I ² = 68%) abilities of older adults with mild cognitive impairment. The meta-analysis indicated that after virtual reality combined cognitive and physical interventions, effects on memory (SMD = −0.03, 95% CI = −0.60 to 0.55, P = 0.78, I ² = 0%) and executive function/attention (SMD = −0.19, 95% CI = −0.74 to 0.36, P = 0.09, I ² = 53%) were not statistically significant.ConclusionsThe present meta-analysis verifies the potential rehabilitative effects of virtual reality combined cognitive and physical interventions for older adults with mild cognitive impairment. More research is also needed to determine the optimal intensity and timing of interventions in the future.     

The effects of aerobic exercise and transcranial direct current stimulation on cognitive function in older adults with and without cognitive impairment: A systematic review and meta-analysis

BackgroundAerobic exercise (AE) may slow age-related cognitive decline. However, such cognition-sparing effects are not uniform across cognitive domains and studies. Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation and is also emerging as a potential alternative to pharmaceutical therapies. Like AE, the effectiveness of tDCS is also inconsistent for reducing cognitive impairment in ageing. The unexplored possibility exists that pairing AE and tDCS could produce synergistic effects and reciprocally augment cognition-improving effects in older individuals with and without cognitive impairments.Previous research found such synergistic effects on cognition when cognitive training is paired with tDCS in older individuals with and without mild cognitive impairment (MCI) or dementia.AimThe purpose of this systematic review with meta-analysis was to explore if pairing AE with tDCS could augment singular effects of AE and tDCS on global cognition (GC), working memory (WM) and executive function (EF) in older individuals with or without MCI and dementia.MethodsUsing a PRISMA-based systematic review, we compiled studies that examined the effects of AE alone, tDCS alone, and AE and tDCS combined on cognitive function in older individuals with and without mild cognitive impairment (MCI) or dementia. Using a PICOS approach, we systematically searched PubMed, Scopus and Web of Science searches up to December 2021, we focused on ‘MoCA’, ‘MMSE’, ‘Mini-Cog’ (measures) and ‘cognition’, ‘cognitive function’, ‘cognitive’, ‘cognitive performance’, ‘executive function’, ‘executive process’, ‘attention’, ‘memory’, ‘memory performance’ (outcome terms). We included only randomized controlled trials (RTC) in humans if available in English full text over the past 20 years, with participants’ age over 60. We assessed the methodological quality of the included studies (RTC) by the Physiotherapy Evidence Database (PEDro) scale.ResultsOverall, 68 studies were included in the meta-analyses. AE (ES = 0.56 [95% CI: 0.28–0.83], p = 0.01) and tDCS (ES = 0.69 [95% CI: 0.12–1.26], p = 0.02) improved GC in all three groups of older adults combined (healthy, MCI, demented). In healthy population, AE improved GC (ES = 0.46 [95% CI: 0.22–0.69], p = 0.01) and EF (ES = 0.27 [95% CI: 0.05–0.49], p = 0.02). AE improved GC in older adults with MCI (ES = 0.76 [95% CI: 0.21–1.32], p = 0.01). tDCS improved GC (ES = 0.69 [90% CI: 0.12–1.26], p = 0.02), all three cognitive function (GC, WM and EF) combined in older adults with dementia (ES = 1.12 [95% CI: 0.04–2.19], p = 0.04) and improved cognitive function in older adults overall (ES = 0.69 [95% CI: 0.20–1,18], p = 0.01).ConclusionOur systematic review with meta-analysis provided evidence that beyond the cardiovascular and fitness benefits of AE, pairing AE with tDCS may have the potential to slow symptom progression of cognitive decline in MCI and dementia. Future studies will examine the hypothesis of this present review that a potentiating effect would incrementally improve cognition with increasing severity of cognitive impairment.     

Does loneliness contribute to mild cognitive impairment and dementia? A systematic review and meta-analysis of longitudinal studies

There is growing evidence that loneliness is associated with mild cognitive impairment (MCI) and dementia. However, the extent of this association remains unclear. A systematic review and meta-analysis of longitudinal studies examining this association was conducted. Six electronic databases were searched from inception to November 15^th 2018. A random-effects meta-analysis was performed to obtain pooled estimates and 95% CIs. Studies were also assessed for heterogeneity, methodological quality and publication bias. A total of 4270 hits were retrieved based on the initial search strategy and ten studies met the eligibility criteria involving 37339 individuals (mean age from 64.9 to 83.1 years). Variation between studies was present for the measurement of loneliness as well as for the case ascertainment of MCI and dementia. Loneliness was positively associated with increased risk of dementia (overall RR = 1.26; 95% CI = 1.14, 1.40; n = 8). Due to lack of sufficient data, we could not explore the association between loneliness and risk of MCI through a meta-analysis, but limited evidence suggests a potential effect of loneliness on MCI. A further understanding of the deleterious effects of loneliness on MCI and dementia may assist the design of environmental and psychological interventions to prevent or delay the onset of these neuropsychiatric conditions.     

Hyperhomocysteinemia and risk of incident cognitive outcomes: An updated dose-response meta-analysis of prospective cohort studies

ObjectiveThis study aimed to comprehensively assess the dose-response relationship between blood homocysteine levels and risk of all cause, Alzheimer and vascular dementia, as well as cognitive impairment without dementia (CIND).MethodWe searched for all related prospective cohort studies reporting homocysteine as an exposure from patients with cognitive disorders as a result in the PubMed and EMBASE databases up to June 18, 2018. Pooled relative risks (RRs) and corresponding 95% confidence intervals (CIs) were extracted. The dose-response meta-analyses were conducted to assess potential linear and non-linear dose-response relations. Summary RRs and 95% CIs were calculated using a random- or fixed-effects model.ResultsTwenty-eight prospective cohort studies were eligible in this meta-analysis. During average follow-up periods ranging from 2.7 to 35 years there were 2557 cases (1035 all-cause dementia, 530 Alzheimer’s disease, 92 vascular dementia and > 900 CIND) among 28,257 participants. There was a clear linear dose-response relationship between blood homocysteine concentration and risk of Alzheimer-type dementia (P > 0.05 for non-linearity). The pooled RR of Alzheimer-type dementia was 1.15 (95% CI: 1.04 to 1.26; I² = 56.6%, n = 5) for every 5 μmol/L increase in blood homocysteine. Sensitivity analysis showed similar results, and there was no clear evidence of publication bias with Begg’s and Egger’s tests for Alzheimer dementia (P = 0.806, 0.084, respectively), strengthening the linear relationship between blood homocysteine levels and risk of Alzheimer dementia. Due to the presence of publication bias and low statistical power, elevated levels of blood homocysteine were not appreciably associated with risk of all-cause, vascular dementia and CIND.ConclusionsEvery 5 μmol/L increase in blood homocysteine is linearly associated with a 15% increase in relative risk of Alzheimer-type dementia. This meta-analysis provides further evidence that a higher concentration of blood homocysteine is associated with a higher risk of Alzheimer-type dementia.     

Subjective cognitive decline predicts future deterioration in cognitively normal patients with Parkinson's disease

Increasing evidence suggests that subjective cognitive decline (SCD) is a potential predictor of future cognitive decline or dementia. We investigated whether SCD in patients with Parkinson's disease (PD) is a predictor of future cognitive decline. Forty-six cognitively normal patients with PD were selected using comprehensive neuropsychological tests, and classified depending on the presence (PD-SCD⁺, n = 25) or absence of SCD (PD-SCD⁻, n = 21). After a mean follow-up of 2.4 years, we repeated the cognitive assessments with the same subjects. The clinical characteristics and cognitive performance of the 2 groups did not differ at baseline. At the follow-up assessment, 11 patients in the PD-SCD⁺ group (44.0%) and 2 in the PD-SCD⁻ group (9.5%) were diagnosed with mild cognitive impairment (MCI), and the PD-SCD⁺ patients showed more rapid decline in semantic fluency and visuospatial memory tasks than those in the PD-SCD⁻ group. A multivariate logistic regression analysis showed that presence of SCD (odds ratio, 8.378; 95% confidential interval, 1.472–47.683, p = 0.017) and higher Unified PD Rating Scale motor score of 20 or more (odds ratio, 4.539; 95% confidential interval, 1.004–20.528; p = 0.049) were risk factors for incident MCI. Present results demonstrate that SCD in cognitively normal patients with PD is an independent risk factor for incident MCI and acts as a predictor for future cognitive decline.     

Cross-sectional and longitudinal associations between adherence to Mediterranean diet with physical performance and cognitive function in older adults: A systematic review and meta-analysis

ObjectivesThe present study investigated the association between adherence to Mediterranean diet (MeDi) and physical performance and cognitive function in older adults.MethodsWe conducted a systematic review and meta-analysis of cross-sectional and longitudinal studies that investigated older adults aged 60+ years and assessed adherence to MeDi diet using validated composite scores. Observational studies, including cross-sectional, case-control, and longitudinal cohort studies, if crude baseline data was available, which investigated as a primary or secondary outcome the association of MeDi diet adherence with physical performance and/or cognitive function in non-demented older adults were included in the cross-sectional analysis. For the longitudinal analysis, case-control and longitudinal cohort studies that investigated the longitudinal associations between adherence to MeDi diet with the incidence of mild cognitive impairment (MCI), dementia, and/or Alzheimer’s disease (AD), and/or changes in physical performance and cognition in non-demented older adults were included. Studies published in other languages than English were excluded. Studies were retrieved from MEDLINE, SCOPUS, CINAHL, and AgeLine databases until May 19, 2021. The risk of bias was evaluated using the Newcastle - Ottawa Quality Assessment Scale (NOS). A pooled effect size was calculated based on standard mean differences (SMD), log odds ratio (OR) and log risk ratio (RR). This study is registered on PROSPERO (CRD42021250254).ResultsNineteen cross-sectional studies that investigated 19.734 community-dwelling and institutionalized older adults free of disability and dementia were included. A high adherence to MeDi was cross-sectionally associated with better walking speed (SMD = 0.42; 95 % Confidence Interval (CI) = 0.12–0.72, P = 0.006; I² = 65 %, P = 0.06), knee muscle strength speed (SMD = 0.26; 95 % CI = 0.17–0.36, P < 0.00001; I² = 0 %, P = 0.69), global cognition (SMD = 0.24; 95 % CI = 0.15–0.33, P < 0.00001; I² = 85 %, P < 0.00001), and memory (SMD = 0.18; 95 % CI = 0.13–0.25, P < 0.00001; I² = 100 %, P < 0.00001). The association between MeDi adherence and global cognition remained significant after stratifying the analysis by the region where the study was conducted, MeDi diet adherence composite score, and Mini Mental State Examination (MMSE). Studies had a moderate to low risk of bias. In relation to longitudinal analysis, thirty-four prospective studies with an average follow-up period that varied from 3.0 to 12.6 years and investigated 98.315 community-dwellers were included. Results indicated that older adults with high MeDi scores had a lower decline in global cognition RR = 0.26; 95 % CI = 0.23–0.29, P < 0.00001; I² = 100 %, P < 0.00001). In contrast, no significant associations between MeDi and mobility, MCI, dementia were found. A low risk of bias was found in the longitudinal studies.DiscussionFindings of the present study indicated that high adherence to MeDi was cross-sectionally associated with physical performance and cognitive function. Results of the pooled analysis of longitudinal studies revealed that high adherence to MeDi reduced the risk of global cognitive decline in non-demented older adults. However, no significant associations between MeDi adherence and the incidence of mobility problems, MCI, and dementia were found. Although important, our findings should be carefully interpreted due to the presence of heterogeneity and publication bias.     

Metabolic syndrome, mild cognitive impairment, and progression to dementia. The Italian Longitudinal Study on Aging

We investigated the relationship of metabolic syndrome (MetS) and its individual components with incidence of mild cognitive impairment (MCI) and its progression to dementia in a large longitudinal Italian population-based sample with a 3.5-year follow-up. A total of 2097 participants from a sample of 5632 65-84-year-old subjects from the Italian Longitudinal Study on Aging were evaluated. MetS was defined according to the Third Adults Treatment Panel of the National Cholesterol Education Program criteria. MCI, dementia, Alzheimer's disease (AD), and vascular dementia (VaD) were classified using current published criteria. Among MCI patients those with MetS (N = 49) had a higher risk of progression to dementia (HR, 4.40; 95% CI, 1.30-14.82) compared with those without MetS (N = 72). After a multivariate adjustment, the risk in MCI patients with MetS approximately doubled (multivariate adjusted HR, 7.80, 95% CI 1.29-47.20) compared with those MCI without MetS. Finally, among non-cognitively impaired individuals there were no significant differences in risks of developing MCI in those who were affected by MetS (N = 608) in comparison with those without MetS (N = 837), as well as excluding those individuals with undernutrition or low inflammatory status with or without undernutrition. In our population, among MCI patients the presence of MetS independently predicted an increased risk of progression to dementia over 3.5 years of follow-up.     

Predicting incident dementia and mild cognitive impairment in older women with nonparametric analysis of circadian activity rhythms in the Study of Osteoporotic Fractures

Study ObjectivesDisrupted daily rhythms are associated with mild cognitive impairment (MCI) and dementia. The specific nature of how rhythms and cognition are related, however, is unknown. We hypothesized characteristics from a nonparametric estimate of circadian rest-activity rhythm patterns would be associated to the development of MCI or dementia.MethodsWrist actigraphy from 1232 cognitively healthy, community-dwelling women (mean age 82.6 years) from the Study of Osteoporotic Fractures was used to estimate rest-activity patterns, including intradaily variability (IV), interdaily stability (IS), most active 10-hour period (M10), least active 5-hour period (L5), and relative amplitude (RA). Logistic regression examined associations of these predictors with 5-year incidence of MCI or dementia. Models were adjusted for potential confounders.ResultsWomen with earlier sleep/wake times had higher risk of dementia, but not MCI, (early vs. average L5 midpoint: OR, 1.66; 95% CI, 1.08–2.55) as did women with smaller day/night activity differentials (low vs. high RA: OR, 1.96; 95% CI, 1.14–3.35). IV, IS, and M10 were not associated with MCI or dementia.ConclusionThe timing and difference in day/night amplitude, but not variability of activity, may be useful as predictors of dementia.     

Depression and bone loss as risk factors for cognitive decline: A systematic review and meta-analysis

BackgroundDepression is linked to Alzheimer’s disease (AD) but it is unclear whether depression is also associated with cognitive decline in the preclinical phase and mild cognitive impairment (MCI). Previous meta-analyses have only investigated AD as an outcome without accounting for individuals showing cognitive decline that does not meet the diagnostic criteria for AD. Other potentially modifiable risk factors such as bone loss have also been less explored and there remains uncertainty around their temporal relationship with cognitive decline.AimsTo conduct a systematic review and meta-analysis investigating depression and bone loss as risk factors for subsequent cognitive decline.MethodsA comprehensive search strategy was developed and applied using four databases; MEDLINE Complete, Embase, PsycINFO and CINAHL Complete. The pooled summary effects were estimated as odds ratios with 95% confidence intervals using a random-effects model. The study protocol was registered with PROSPERO (ID: CRD42020159369).ResultsA total of 75 longitudinal cohort studies were identified for meta-analysis, of which 70 examined the impact of depression on cognitive decline and five examined the impact of bone loss. Prior exposure to depression was found to be associated with cognitive score reduction (OR 1.33 95% CI 1.17, 1.51), MCI incidence (OR 1.52 95% CI 1.28, 1.79) and AD incidence (OR 1.79 95% CI 1.46, 2.2). Bone loss was also associated with the incidence of AD (OR=1.81 95% CI 1.28, 2.55).ConclusionsOverall, the results support the hypothesis that depression is associated with subsequent cognitive decline. Bone loss was also found to be associated with AD incidence; however, due to the small number of studies, the results should be viewed with caution.     

APOE, ACT and CHRNA7 genes in the conversion from amnestic mild cognitive impairment to Alzheimer's disease

We have investigated whether the -86 C/T promoter polymorphism in CHRNA7 gene, the signal peptide polymorphism of the alpha1-antichymotripsin (ACT) gene or the APOE genotype are associated with an increased risk of mild cognitive impairment (MCI) or affect the risk of evolution to Alzheimer's disease (AD). We have followed up 89 patients with initial diagnoses of amnestic MCI for 49 months. Patients were separated into three groups: 27 subjects who remained with MCI, 40 that converted to AD before 20 months and 22 that converted to AD after. To assess the risk associated to each genotype a control group (n=90) without cognitive impairment was included. APOE4 allele was associated with an increased risk of MCI (OR: 6.04, 95% CI: 2.76-3.23; p<0.001) but did not have an effect on the probability of evolving AD. ACT or CHRNA7 genotypes were not associated with MCI but both appear to modify the risk of progression to dementia in opposing manners: ACT polymorphism increasing the risk to evolve to AD before 20 months (HR=2.03; 95% CI: 1-4.6; p=0.06) and CHRNA7 polymorphism protecting from evolution to dementia. Cox regression model demonstrated that ACT genotype confers a higher risk of rapid evolution to dementia than age or years of schooling. We conclude that APOE is a risk gene for amnestic MCI and that ACT and CHRNA7 may act in these patients as modifier genes for the time of progression to AD.     

Depression and risk of sudden cardiac death after acute myocardial infarction: testing for the confounding effects of fatigue

OBJECTIVES: This study examined the impact of depressive symptoms and social support on 2-year sudden cardiac death (SCD) risk, controlling for fatigue symptoms. METHODS: Myocardial infarction (MI) patients (N = 671) participating in the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial completed measures of depression, hostility, and social support. RESULTS: After controlling for significant biological predictors, psychosocial predictors of increased SCD risk in the survival analysis were greater social network contacts (RR = 1.04; 95% CI = 1.01-1.06; p < .007), lower social participation (RR = 0.98; 95% CI = 0.96-1.00; p < .05), and, in placebo-treated patients, elevated depressive symptoms (RR = 2.45; 95% CI = 1.14-5.35; p < .02). Fatigue was associated with SCD (RR = 1.31; 95% CI = 1.11-1.53; p < .001), and, when included in the model, diminished the influence of depression (RR = 1.73; 95% CI = 0.75-3.98; p = .20). When the cognitive-affective depressive symptoms were examined separately from somatic symptoms, there was a trend for an association between cognitive-affective symptoms and SCD in placebo-treated patients after controlling for fatigue (RR = 1.09; 95% CI = 0.99-1.19, p < .06). CONCLUSIONS: Symptoms of depression and fatigue overlap in patients with MI. The trend for the cognitive-affective symptoms of depression to be associated with SCD risk, even after controlling for dyspnea/fatigue, suggests that the association between depression and mortality after AMI cannot be entirely explained as a confound of cardiac-related fatigue. The independent contribution of social participation suggests a role of both depressive symptomatology and social factors in influencing mortality risk after MI.     

Vascular predictors of cognitive decline in patients with mild cognitive impairment

Our aim in this study was to assess the relationship between the state of cerebral vessels and the risk of conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD). We included 117 MCI patients. They underwent an ultrasonographic assessment of common carotid arteries intima-media thickness (IMT) and carotid plaque index. Cerebrovascular reactivity to hypercapnia in the middle cerebral arteries was calculated with the Breath-Holding Index (BHI). After a 12-month follow-up period, neuropsychological examinations demonstrated a progression to dementia in 21 patients. Pathological values of BHI and IMT significantly increased the risk of conversion (BHI: odds ratio, 5.80; 95% confidence interval, 1.83-18.37, p < 0.05; IMT: odds ratio, 3.08; 95% confidence interval, 1.02-9.33; p < 0.05, multinomial logistic regression analysis). Comparison between patients with all normal values and those with the simultaneous alteration of the 2 vascular indexes showed an increase in the risk of conversion from 9% to 33% (ordinal regression analysis). Our findings show that alterations of cerebral vessel functional and anatomic status increase the risk of conversion from MCI to dementia.     

Subclassifications for mild cognitive impairment: prevalence and predictive validity

BACKGROUND: Mild cognitive impairment (MCI) is associated with an increased risk of developing dementia. Recently published results of the Current Concepts in MCI Conference suggested subclassifications for MCI (MCI-amnestic, MCI-multiple domains slightly impaired, MCI-single nonmemory domain) based on the recognized heterogeneity in the use of the term. These subclassifications have not been empirically validated to date. METHOD: A community sample of 1045 dementia-free individuals aged 75 years and over was examined by neuropsychological testing in a three-wave longitudinal study. The prevalences and the predictive validities for the subclassifications of MCI and their modifications (original criteria except for the report of subjective decline in cognitive function) were determined. RESULTS: The prevalence was 1 to 15% depending on the subset employed. Subjects with a diagnosis of MCI progressed to dementia at a rate of 10 to 55% over 2.6 years, depending on the subset employed. MCI-amnestic achieved the highest positive predictive power (PPP). ROC curves of the subclassifications for MCI indicate that all but one subset for MCI failed to predict dementia (MCI-multiple domains slightly impaired-modified: AUC=0.585, P<0.01, 95% CI, 0.517-0.653). The use of modified criteria for MCI (original criteria except for the report of subjective decline in cognitive function) is associated with a higher diagnostic sensitivity but also with a reduction in diagnostic specificity and PPP. CONCLUSIONS: Modified criteria should be applied if a concept for MCI with a high sensitivity is required and the original criteria (including subjective cognitive complaint) if a concept with high specificity and high PPP is required.     

Association of HIV infection and cognitive impairment in older adults: A meta-analysis

ObjectiveTo synthesize evidence on the association between human immunodeficiency virus (HIV) infection and cognitive impairment in older adults.DesignMeta-analysis.ParticipantsAdults aged 50 years or older.MethodsIn this systematic literature review and meta-analysis, we searched PubMed, Scopus, Embase, and APA/PsycNet for studies published before July 21, 2020, that assessed the association between HIV-infection and cognitive impairment. We calculated pooled odds ratios (ORs) of cognitive impairment for people living with HIV (PLWH) and 95 % confidence intervals (CIs) using random-effect models and calculated pooled mean difference (MD) for major cognitive domains between PLWH and HIV-uninfected adults. We assessed risk of bias using the Newcastle-Ottawa scale.ResultsOf the 4432 studies identified, 21 cross-sectional studies were eligible for the meta-analysis, including 15 examining global cognitive impairment. The meta-analysis showed that older PLWH were more likely to be cognitively impaired than HIV-uninfected controls (OR = 2.44, 95 % CI = [1.69, 3.53], number of estimates (k) = 15, I² = 71 %). This higher likelihood was shown in studies from high income countries (OR = 2.63, 95 % CI = [1.76, 3.94], k = 12, I² = 55 %), but not from upper-middle income countries (OR = 1.96, 95 % CI = [0.26, 14.68], k = 3, I² = 91 %). PLWH had lower scores than HIV-uninfected adults in 5 out of 7 major cognitive domains, including executive function (MD = -0.42, 95 % CI = [-0.72, -0.11], k = 5, I² = 32 %), processing speed (MD = -0.33, 95 % CI = [-0.59, -0.08], k = 6, I² = 16 %), verbal (MD=-0.29, 95 % CI = [-0.48, -0.10], k = 6, I² = 0%), recall (MD = -0.24, 95 % CI = [-0.38, -0.10], k = 6, I² = 0%) and motor/psychomotor (MD = -0.38, 95 % CI = [-0.59, -0.16], k = 5, I² = 31 %) performance.Conclusions/implicationsOur meta-analysis provides empirical evidence that HIV infection is associated with an increased risk of cognitive impairment among older adults, especially in cognitive domains of executive function, processing speed, verbal, recall, and motor/psychomotor.     

Mild cognitive decline. A position statement of the Cognitive Decline Group of the European Innovation Partnership for Active and Healthy Ageing (EIPAHA)

IntroductionMild cognitive impairment (MCI) is a term used to describe a level of decline in cognition which is seen as an intermediate stage between normal ageing and dementia, and which many consider to be a prodromal stage of neurodegeneration that may become dementia. That is, it is perceived as a high risk level of cognitive change. The increasing burden of dementia in our society, but also our increasing understanding of its risk factors and potential interventions, require diligent management of MCI in order to find strategies that produce effective prevention of dementia.AimTo update knowledge regarding mild cognitive impairment, and to bring together and appraise evidence about the main features of clinical interest: definitions, prevalence and stability, risk factors, screening, and management and intervention.MethodsLiterature review and consensus of expert opinion.Results and conclusionMCI describes a level of impairment in which deteriorating cognitive functions still allow for reasonable independent living, including some compensatory strategies. While there is evidence for some early risk factors, there is still a need to more precisely delineate and distinguish early manifestations of frank dementia from cognitive impairment that is less likely to progress to dementia, and furthermore to develop improved prospective evidence for positive response to intervention. An important limitation derives from the scarcity of studies that take MCI as an endpoint. Strategies for effective management suffer from the same limitation, since most studies have focused on dementia. Behavioural changes may represent the most cost-effective approach.     

Risk factors for falls in older people with cognitive impairment living in the community: Systematic review and meta-analysis

PurposeThis systematic review aimed to identify risk factors for prospectively ascertained falls, focusing on those that are potentially modifiable (physical and neuropsychological factors), in older people with cognitive impairment living in the community.ResultsA comprehensive search of five databases identified 16 high quality (Newcastle-Ottawa Scale ≥8/9) relevant articles. Meta-analyses were undertaken for five potential fall risk factors. Of these, fallers had significantly poorer balance (standardized mean difference = 0.62, 95 %CI 0.45, 0.79) with low heterogeneity. Global cognition was not significantly associated with faller status in a meta-analysis with low heterogeneity. Meta-analyses of mobility (Timed Up-and-Go), gait speed and depressive symptoms had high heterogeneity and were not statistically significant or were borderline significant (p = 0.05). Sensitivity analyses (removing one study sample’s results that differed markedly from the other included samples) reduced heterogeneity to 0% and revealed fallers had significantly poorer mobility and more depressive symptoms than non-fallers. Fallers also walked significantly slower, but heterogeneity remained high.ConclusionsIn older people with cognitive impairment, fallers presented with balance deficits, poor mobility, slow gait speed and depressive symptoms. Reduced global cognition was not associated with falls. These findings suggest that interventions should target balance impairment and reveal that more high-quality research is needed.     

Positive psychological constructs and association with reduced risk of mild cognitive impairment and dementia in older adults: A systematic review and meta-analysis

Understanding factors associated with dementia risk is important for informing future interventions aimed at dementia prevention. There is accumulating evidence for the association between depression and risk of dementia, however less is known about the association between positive psychological factors and dementia incidence. This review aims to synthesise evidence regarding the association between positive psychological constructs (PPCs) and later risk of MCI and dementia in adults aged 50 and over. Literature searches were conducted in Medline, PsycINFO, and Scopus until March 2021. Papers reporting on the association between at least one PPC and later risk of MCI or dementia in people aged 50 + without cognitive impairment at baseline were included. Results from the meta-analyses revealed that purpose in life was significantly associated with a reduced risk of dementia (HR = 0.81, 95% CI [0.78, 0.85], p < .001), however results for positive affect were non-significant (HR = 0.94, 95% CI [0.76, 1.15], p = .54). Results for other PPCs are described narratively. Mixed findings for different PPCs highlight the importance of investigating these factors individually. Understanding which factors may play a protective role in their association with risk of mild cognitive impairment and dementia could have important implications for informing dementia prevention interventions.     

Sex differences in the prevalence and incidence of mild cognitive impairment: A meta-analysis

ObjectiveMore women have Alzheimer’s disease (AD) than men. Understanding sex differences in mild cognitive impairment (MCI) may further knowledge of AD etiology and prevention. We conducted a meta-analysis to examine sex differences in the prevalence and incidence of MCI, which included amnestic and non-amnestic subtypes.MethodSystematic searches were performed in July 2015 using MEDLINE/PubMed, Scopus, and PsycINFO for population-or community-based studies with MCI data for men and women. Random-effects model were used.ResultsFifty-six studies were included. There were no statistically significant sex differences in prevalence or incidence of amnestic MCI. There was a significantly higher prevalence (p = 0.038), but not incidence, of non-amnestic MCI among women. There were no sex differences in studies that combined both subtypes of MCI.ConclusionThe only statistically significant finding emerging from this study was that women have a higher prevalence of non-amnestic MCI. To better understand sex differences in the preclinical stages of dementia, studies must better characterize the etiology of the cognitive impairment.     

Sleep and subjective cognitive decline in cognitively healthy elderly: Results from two cohorts

Subjective cognitive decline may reflect a dementia prodrome or modifiable risk factor such as sleep disturbance. What is the association between sleep and subjective cognitive decline? Cross‐sectional design, from two studies of older adults: the WHICAP in the USA and the HELIAD in Greece. A total of 1,576 WHICAP and 1,456 HELIAD participants, without mild cognitive impairment, dementia or severe depression/anxiety, were included. Participants were mostly women, with 12 (WHICAP) and 8 (HELIAD) mean years of education. Sleep problems were estimated using the Sleep Scale from the Medical Outcomes Study. Subjective cognitive decline was assessed using a structured complaint questionnaire that queries for subjective memory and other cognitive symptoms. Multinomial or logistic regression models were used to examine whether sleep problems were associated with complaints about general cognition, memory, naming, orientation and calculations. Age, sex, education, sleep medication, use of medications affecting cognition, co‐morbidities, depression and anxiety were used as co‐variates. Objective cognition was also estimated by summarizing neuropsychological performance into composite z‐scores. Sleep problems were associated with two or more complaints: WHICAP: β = 1.93 (95% confidence interval: 1.59–2.34), p ≤ .0001; HELIAD: β = 1.48 (95% confidence interval: 1.20–1.83), p ≤ .0001. Sleep problems were associated with complaints in all the cognitive subcategories, except orientation for the WHICAP. The associations were noted regardless of objective cognition. At any given level of objective cognition, sleep disturbance is accompanied by subjective cognitive impairment. The replicability in two ethnically, genetically and culturally different cohorts adds validity to our results. The results have implications for the correlates, and potential aetiology of subjective cognitive decline, which should be considered in the assessment and treatment of older adults with cognitive complaints.