Social health and subsequent cognitive functioning in people aged 50 years and older: examining the mediating roles of depressive symptoms and inflammatory biomarkers in two European longitudinal studies.

BACKGROUND: Social health markers, including marital status, contact frequency, network size, and social support, have been shown to be associated with cognition. However, the mechanisms underlying these associations remain poorly understood. We investigated whether depressive symptoms and inflammation mediated associations between social health and subsequent cognition. METHODS: In the English Longitudinal Study of Ageing (ELSA), a nationally representative longitudinal study in England, UK, we sampled 7136 individuals aged 50 years or older living in private households without dementia at baseline or at the intermediate mediator assessment timepoint, who had recorded information on at least one social health marker and potential mediator. We used four-way decomposition to examine to what extent depressive symptoms, C-reactive protein, and fibrinogen mediated associations between social health and subsequent standardised cognition (verbal fluency and delayed and immediate recall), including cognitive change, with slopes derived from multilevel models (12-year slope). We examined whether findings were replicated in the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), a population-based longitudinal study in Sweden, in a sample of 2604 individuals aged 60 years or older living at home or in institutions in Kungsholmen (central Stockholm) without dementia at baseline or at the intermediate mediator assessment timepoint (6-year slope). Social health exposures were assessed at baseline, potential mediators were assessed at an intermediate timepoint (wave 2 in ELSA and 6-year follow-up in SNAC-K); cognitive outcomes were assessed at a single timepoint (wave 3 in ELSA and 12-year follow-up in SNAC-K), and cognitive change (between waves 3 and 9 in ELSA and between 6-year and 12-year follow-ups in SNAC-K). FINDINGS: The study sample included 7136 participants from ELSA, of whom 3962 (55·5%) were women and 6934 (97·2%) were White; the mean baseline age was 63·8 years (SD 9·4). Replication analyses included 2604 participants from SNAC-K, of whom 1604 (61·6%) were women (SNAC-K did not collect ethnicity data); the mean baseline age was 72·3 years (SD 10·1). In ELSA, we found indirect effects via depressive symptoms of network size, positive support, and less negative support on subsequent verbal fluency, and of positive support on subsequent immediate recall (pure indirect effect [PIE] 0·002 [95% CI 0·001-0·003]). Depressive symptoms also partially mediated associations between less negative support and slower decline in immediate recall (PIE 0·001 [0·000-0·002]) and in delayed recall (PIE 0·001 [0·000-0·002]), and between positive support and slower decline in immediate recall (PIE 0·001 [0·000-0·001]). We did not observe mediation by inflammatory biomarkers. Findings of mediation by depressive symptoms in the association between positive support and verbal fluency and between positive support and change in immediate recall were replicated in SNAC-K. INTERPRETATION: The findings of this study provide new insights into mechanisms linking social health with cognition, suggesting that associations between interactional aspects of social health, especially social support, and cognition are partly underpinned by depressive symptoms. FUNDING: EU Joint Programme-Neurodegenerative Disease Research (JPND) and Alzheimer's Society. TRANSLATION: For the Swedish translation of the abstract see Supplementary Materials section.

Examining the Interrelationships Between Social Isolation and Loneliness and Their Correlates Among Older British Adults Before and During the COVID-19 Lockdown: Evidence From Four British Longitudinal Studies.

Background and Objectives: Unprecedented social restrictions during the coronavirus disease 2019 (COVID-19) pandemic have provided a new lens for considering the interrelationship between social isolation and loneliness in later life. We present these interrelationships before and during the COVID-19 restrictions and investigate to what extent demographic, socioeconomic, and health factors associated with such experiences differed during the pandemic. Research Design and Methods: We used data from four British longitudinal population-based studies (1946 NSHD, 1958 NCDS, 1970 BCS, and ELSA, N = 12,129). Rates, co-occurrences, and correlates of social isolation and loneliness are presented prior to and during the early stage of the COVID-19 pandemic and the interrelationships between these experiences are elucidated in both periods. Results: Across the Four studies, prepandemic proportions reporting social isolation ranged from 15% to 54%, with higher rates in older ages (e.g., 32% of individuals aged 70-79 years and 54% of those more than 80). During the pandemic, the percentage of older people reporting both social isolation and loneliness and isolation only slightly increased. The interrelationship between social isolation and loneliness did not change. Associations between sociodemographic and health characteristics and social isolation and loneliness also remained consistent, with greater burden among those with higher economic precarity (females, nonhomeowners, unemployed, illness, and greater financial stress). Discussion and Implications: There were already large inequalities in experiences of social isolation and loneliness and the pandemic had a small impact on worsening extent and inequalities in these. The concepts of loneliness and social isolation are not interchangeable, and clarity is needed in how they are conceptualized, operationalized, and interpreted. Given many older adults experience high levels of social isolation, there should be greater emphasis on reducing social isolation and the inequalities observed in who experiences greater isolation and loneliness.

Lifecourse investigation of the cumulative impact of adversity on cognitive function in old age and the mediating role of mental health: longitudinal birth cohort study.

OBJECTIVE: To investigate the accumulation of adversities (duration of exposure to any, economic, psychosocial) across the lifecourse (birth to 63 years) on cognitive function in older age, and the mediating role of mental health. DESIGN: National birth cohort study. SETTING: Great Britain. PARTICIPANTS: 5362 singleton births within marriage in England, Wales and Scotland born within 1 week of March 1946, of which 2131 completed at least 1 cognitive assessment. MAIN OUTCOME MEASURES: Cognitive assessments included the Addenbrooke's Cognitive Examination-III, as a measure of cognitive state, processing speed (timed-letter search task), and verbal memory (word learning task) at 69 years. Scores were standardised to the analytical sample. Mental health at 60-64 years was assessed using the 28-item General Health Questionnaire, with scores standardised to the analytical sample. RESULTS: After adjusting for sex, increased duration of exposure to any adversity was associated with decreased performance on cognitive state (ß=-0.39; 95% CI -0.59 to -0.20) and verbal memory (ß=-0.45; 95% CI -0.63 to -0.27) at 69 years, although these effects were attenuated after adjusting for further covariates (childhood cognition and emotional problems, educational attainment). Analyses by type of adversity revealed stronger associations from economic adversity to verbal memory (ß=-0.54; 95% CI -0.70 to -0.39), with a small effect remaining even after adjusting for all covariates (ß=-0.18; 95% CI -0.32 to -0.03), and weaker associations from psychosocial adversity. Causal mediation analyses found that mental health mediated all associations between duration of exposure to adversity (any, economic, psychosocial) and cognitive function, with around 15% of the total effect of economic adversity on verbal memory attributable to mental health. CONCLUSIONS: Improving mental health among older adults has the potential to reduce cognitive impairments, as well as mitigate against some of the effect of lifecourse accumulation of adversity on cognitive performance in older age.

Social Health and Change in Cognitive Capability among Older Adults: Findings from Four European Longitudinal Studies.

INTRODUCTION: In this study, we examine whether social health markers measured at baseline are associated with differences in cognitive capability and the rate of cognitive decline over an 11-to-18-year period among older adults and compare results across studies. METHODS: We applied an integrated data analysis approach to 16,858 participants (mean age 65 years; 56% female) from the National Survey for Health and Development (NSHD), the English Longitudinal Study of Aging (ELSA), the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), and the Rotterdam Study. We used multilevel models to examine social health in relation to cognitive capability and the rate of cognitive decline. RESULTS: Pooled estimates show distinct relationships between markers of social health and cognitive domains, e.g., a large network size (≥6 people vs. none) was associated with higher executive function (0.17 standard deviation [SD] [95% CI: 0.00, 0.34], I2 = 27%) but not with memory (0.08 SD [95% CI: -0.02, 0.18], I2 = 19%). We also observed pooled associations between being married or cohabiting, having a large network size, and participating in social activities with slower decline in cognitive capability. However, estimates were close to zero, e.g., 0.01 SD/year (95% CI: 0.01, 0.02) I2 = 19% for marital status and executive function. There were clear study-specific differences: results for average processing speed were the most homogenous, and results for average memory were the most heterogeneous. CONCLUSION: Overall, markers of good social health have a positive association with cognitive capability. However, we found differential associations between specific markers of social health and cognitive domains and differences between studies. These findings highlight the importance of examining between-study differences and considering the context specificity of findings in developing and deploying interventions.

Social connections and risk of incident mild cognitive impairment, dementia, and mortality in 13 longitudinal cohort studies of ageing.

INTRODUCTION: Previous meta-analyses have linked social connections and mild cognitive impairment, dementia, and mortality. However, these used aggregate data from North America and Europe and examined a limited number of social connection markers. METHODS: We used individual participant data (N = 39271, Mage  = 70.67 (40-102), 58.86% female, Meducation  = 8.43 years, Mfollow-up  = 3.22 years) from 13 longitudinal ageing studies. A two-stage meta-analysis of Cox regression models examined the association between social connection markers with our primary outcomes. RESULTS: We found associations between good social connections structure and quality and lower risk of incident mild cognitive impairment (MCI); between social structure and function and lower risk of incident dementia and mortality. Only in Asian cohorts, being married/in a relationship was associated with reduced risk of dementia, and having a confidante was associated with reduced risk of dementia and mortality. DISCUSSION: Different aspects of social connections - structure, function, and quality - are associated with benefits for healthy aging internationally. HIGHLIGHTS: Social connection structure (being married/in a relationship, weekly community group engagement, weekly family/friend interactions) and quality (never lonely) were associated with lower risk of incident MCI. Social connection structure (monthly/weekly friend/family interactions) and function (having a confidante) were associated with lower risk of incident dementia. Social connection structure (living with others, yearly/monthly/weekly community group engagement) and function (having a confidante) were associated with lower risk of mortality. Evidence from 13 longitudinal cohort studies of ageing indicates that social connections are important targets for reducing risk of incident MCI, incident dementia, and mortality. Only in Asian cohorts, being married/in a relationship was associated with reduced risk of dementia, and having a confidante was associated with reduced risk of dementia and mortality.

Psychological distress, depression, anxiety, and life satisfaction following COVID-19 infection: evidence from 11 UK longitudinal population studies.

BACKGROUND: Evidence on associations between COVID-19 illness and mental health is mixed. We aimed to examine whether COVID-19 is associated with deterioration in mental health while considering pre-pandemic mental health, time since infection, subgroup differences, and confirmation of infection via self-reported test and serology data. METHODS: We obtained data from 11 UK longitudinal studies with repeated measures of mental health (psychological distress, depression, anxiety, and life satisfaction; mental health scales were standardised within each study across time) and COVID-19 status between April, 2020, and April, 2021. We included participants with information available on at least one mental health outcome measure and self-reported COVID-19 status (suspected or test-confirmed) during the pandemic, and a subset with serology-confirmed COVID-19. Furthermore, only participants who had available data on a minimum set of covariates, including age, sex, and pre-pandemic mental health were included. We investigated associations between having ever had COVID-19 and mental health outcomes using generalised estimating equations. We examined whether associations varied by age, sex, ethnicity, education, and pre-pandemic mental health, whether the strength of the association varied according to time since infection, and whether associations differed between self-reported versus confirmed (by test or serology) infection. FINDINGS: Between 21 Dec, 2021, and July 11, 2022, we analysed data from 54 442 participants (ranging from a minimum age of 16 years in one study to a maximum category of 90 years and older in another; including 33 200 [61·0%] women and 21 242 [39·0%] men) from 11 longitudinal UK studies. Of 40 819 participants with available ethnicity data, 36 802 (90·2%) were White. Pooled estimates of standardised differences in outcomes suggested associations between COVID-19 and subsequent psychological distress (0·10 [95% CI 0·06 to 0·13], I2=42·8%), depression (0·08 [0·05 to 0·10], I2=20·8%), anxiety (0·08 [0·05 to 0·10], I2=0·0%), and lower life satisfaction (-0·06 [-0·08 to -0·04], I2=29·2%). We found no evidence of interactions between COVID-19 and sex, education, ethnicity, or pre-pandemic mental health. Associations did not vary substantially between time since infection of less than 4 weeks, 4-12 weeks, and more than 12 weeks, and were present in all age groups, with some evidence of stronger effects in those aged 50 years and older. Participants who self-reported COVID-19 but had negative serology had worse mental health outcomes for all measures than those without COVID-19 based on serology and self-report. Participants who had positive serology but did not self-report COVID-19 did not show association with mental health outcomes. INTERPRETATION: Self-reporting COVID-19 was longitudinally associated with deterioration in mental health and life satisfaction. Our findings emphasise the need for greater post-infection mental health service provision, given the substantial prevalence of COVID-19 in the UK and worldwide. FUNDING: UK Medical Research Council and UK National Institute for Health and Care Research.

Non-affective psychotic disorders and risk of dementia: a systematic review and meta-analysis.

Non-affective psychotic disorders have been associated with an increased risk of developing dementia. However, research in this area remains limited, highlighting the need for an up-to-date systematic review and meta-analysis of the evidence. We aimed to systematically review and quantify the risk of dementia associated with psychotic disorders. We searched four electronic databases for longitudinal studies investigating non-affective psychotic disorders and subsequent dementia. We used random-effects meta-analyses to pool estimates across studies and assessed risk of bias for each study. Non-affective psychotic disorders were associated with increased risk of all-cause dementia; pooled risk ratio (RR) = 2.52, 95% confidence interval (CI) (1.67-3.80), I2 = 99.7%, n = 12,997,101; 11 studies, with high heterogeneity between studies. Subgroup analyses indicated stronger associations in studies with shorter follow-up periods, conducted in non-European countries, published after 2020, and where ≥60% of the sample were female. The risk was higher in people aged <60 years at baseline, in typical and late-onset psychotic disorders versus very late-onset psychosis, in broader psychotic disorders vs schizophrenia, and in prospective vs retrospective studies. Associations remained after excluding low quality studies (pooled RR = 2.50, 95% CI (1.71-3.68), I2 = 99.0%). Our review finds a substantial association between psychotic disorders and subsequent dementia. Our findings indicate that psychotic disorders are a potentially modifiable risk factor for dementia and suggest that individuals with psychotic disorders need to be closely monitored for cognitive decline in later life. Further research is needed to investigate the mechanisms underlying the association between psychotic disorders and dementia.

Psychiatric disorders and risk of subsequent dementia: Systematic review and meta-analysis of longitudinal studies.

OBJECTIVES: Although psychiatric disorders have been found to be associated with increased risk of dementia, previous findings are mixed, and the nature of these relationships remains poorly understood. We examined longitudinal associations between depression, anxiety, post-traumatic stress disorders (PTSD), bipolar disorder (BPD), psychotic disorders and subsequent dementia. METHODS: We searched three databases for longitudinal, population-based studies investigating associations between psychiatric disorders and dementia (PROSPERO registration: CRD42020209638). We conducted narrative synthesis, and random-effects meta-analyses to obtain pooled estimates. We used meta-regression and stratified analyses to examine variation by sex, age-at-onset and follow-up time. RESULTS: Fifty-seven citations met eligibility criteria. Most studies focussed on depression (n = 33), which was associated with subsequent all-cause dementia (pooled relative risk [RR]: 1.96, 95% confidence interval [CI]: 1.59-2.43; I2  = 96.5%), Alzheimer's Disease (pooled RR: 1.9, 95% CI: 1.52-2.38; I2  = 85.5%), and Vascular Dementia (pooled RR: 2.71, 95% CI: 2.48-2.97; I2  = 0). Associations were stronger in studies with shorter follow-up periods and for severe and late-onset depression. Findings regarding anxiety were mixed, and we did not find evidence of an overall association (pooled RR: 1.18, 95% CI: 0.96-1.45; I2  = 52.2%, n = 5). Despite sparse evidence, psychotic disorders (pooled RR: 2.19, 95% CI: 1.44-3.31; I2  = 99%), PTSD and BPD were associated with subsequent dementia. CONCLUSIONS: People with psychiatric disorders represent high-risk groups for dementia, highlighting the importance of ongoing symptom monitoring in these groups. Findings regarding temporality and age-at-onset indicate that depression symptoms could reflect prodromal dementia for some individuals. Further longitudinal research is required to determine whether psychiatric disorders represent causal risk factors or early markers of dementia neuropathology.

Association of Emotion Regulation Trajectories in Childhood With Anorexia Nervosa and Atypical Anorexia Nervosa in Early Adolescence.

Importance: People with anorexia nervosa often experience difficulties regulating their emotions. There is no longitudinal evidence as to whether these differences are already present in childhood or when they begin to emerge. Objective: To investigate the association between emotion regulation trajectories from 3 to 7 years of age and symptoms of anorexia nervosa and atypical anorexia nervosa in adolescence. Design, Setting, and Participants: This cohort study included all children with complete exposure data in the Millennium Cohort Study, a UK general population birth cohort. Data were acquired from June 2001 to March 2016 and analyzed from June to November 2020. Exposures: Mothers reported on their children's emotion regulation skills at 3, 5, and 7 years of age using the Children's Social Behavior Questionnaire. Multilevel models were used to derive early childhood emotion regulation scores (ie, predicted intercept) and within-child changes in emotion regulation scores from 3 to 7 years of age (ie, predicted slope). Main Outcome and Measures: Symptoms consistent with a DSM-5 diagnosis of anorexia nervosa or atypical anorexia nervosa at 14 years of age, defined using a range of questions relative to body image, weight perception, and dieting behaviors (hereinafter referred to as broad anorexia nervosa). Univariable and multivariable logistic regression models tested the association between exposures and outcome. Regression models were adjusted for child and family sociodemographic and socioeconomic characteristics and mental health difficulties, prenatal and perinatal factors, child's cognitive development, and maternal attachment. Results: A total of 15 896 participants (85.7% of total sample; 51.0% boys; 84.5% White individuals) had complete data on the exposure and were included in the main analyses. Among those with complete exposure and outcome data (9912 of the analytical sample [62.4%]), 97 participants (1.0%; 86 [88.7%] girls and 85 [87.6%] White individuals) had symptoms consistent with a diagnosis of broad anorexia nervosa at 14 years of age. No evidence suggested that children with lower emotion regulation ability at 3 years of age had greater odds of later reporting symptoms of broad anorexia nervosa (odds ratio [OR], 1.21; 95% CI, 0.91-1.63). However, children whose emotion regulation skills did not improve over childhood and who had greater problems regulating emotions at 7 years of age had higher odds of having broad anorexia nervosa at 14 years of age (OR, 1.45; 95% CI, 1.16-1.83). Conclusions and Relevance: These findings suggest that difficulties in developing age-appropriate emotion regulation skills in childhood are associated with experiencing broad anorexia nervosa in adolescence. Interventions to support the development of emotion regulation skills across childhood may help reduce the incidence of anorexia nervosa.

Modulation of Amygdala Response by Cognitive Conflict in Adolescents with Conduct Problems and Varying Levels of CU Traits.

Adolescents with conduct problems and low callous-unemotional traits are characterised by high levels of reactive aggression. Prior studies suggest that they can have exaggerated neural and behavioural responses to negative emotional stimuli, accompanied by compromised affect regulation and atypical engagement of prefrontal areas during cognitive control. This pattern may in part explain their symptoms. Clarifying how neurocognitive responses to negative emotional stimuli can be modulated in this group has potential translational relevance. We present fMRI data from a cognitive conflict task in which the requirement to visually scan emotional (vs. calm) faces was held constant across low and high levels of cognitive conflict. Participants were 17 adolescent males with conduct problems and low levels of callous-unemotional traits (CP/LCU); 17 adolescents with conduct problems and high levels of callous-unemotional traits (CP/HCU, who typically show blunted reactivity to fear), and 18 typically developing controls (age range 10-16). Control participants showed typical attenuation of amygdala response to fear relative to calm faces under high (relative to low) conflict, replicating previous findings in a healthy adult sample. In contrast, children with CP/LCU showed a reduced (left amygdala) or reversed (right amygdala) attenuation effect under high cognitive conflict conditions. Children with CP/HCU did not differ from controls. Findings suggest atypical modulation of amygdala response as a function of task demands, and raise the possibility that those with CP/LCU are unable to implement typical regulation of amygdala response when cognitive task demands are high.

Minor and subthreshold depressive disorders in Alzheimer's disease: A systematic review and meta-analysis of prevalence studies.

BACKGROUND: Depressive symptoms are common in Alzheimer's disease (AD) and negatively impact patient well-being. The main aim of the present study was to establish summary estimates for the prevalence of minor depressive disorder (MinD) and subthreshold depression in AD and synthesise evidence on prognosis and management of these symptoms in order to inform clinical guidelines. METHODS: Systematic review and meta-analysis of cross-sectional and longitudinal studies of prevalence, prognosis, and treatments for minor and subthreshold depression in AD. We searched MEDLINE, Embase, PsycINFO and CINAHL. We included studies that reported prevalence of subthreshold depressive disorders and those reporting data on validity of diagnostic criteria, mechanisms, or randomised controlled clinical trials (RCTs) testing effectiveness of interventions. Estimates of prevalence were pooled using random-effects meta-analyses. Two authors screened articles and independently extracted data on study characteristics. RESULTS: We reviewed 5671 abstracts, retrieved 621 full text articles and included a total of 15 studies. Pooling data from 10 studies showed that prevalence for MinD in AD was 22.0% (95% CI 16.0 to 28.0). Prevalence for a clinical diagnosis of MinD (DSM-III-R and DSM-IV) was 26.0% (95% CI 20.0 to 32.0; 6 studies). People with MinD experienced higher levels of neuropsychiatric symptoms, functional and cognitive decline, although studies remain cross-sectional. Neither sertraline nor a carer intervention were effective in reducing symptoms. CONCLUSION: This review finds that MinD is prevalent in people with a diagnosis of AD and requires clinical attention. Research is warranted to develop effective interventions to treat and prevent these symptoms.

The Incidence of Nonaffective, Nonorganic Psychotic Disorders in Older People: A Population-based Cohort Study of 3 Million People in Sweden.

BACKGROUND: There are limited data on the epidemiology of very late-onset schizophrenia-like psychosis (VLOSLP) and how this relates to potential risk factors including migration, sensory impairment, traumatic life events, and social isolation. METHODS: We followed up a cohort of 3 007 378 people living in Sweden, born 1920-1949, from their 60th birthday (earliest: January 15, 1980) until December 30 2011, emigration, death, or first recorded diagnosis of nonaffective psychosis. We examined VLOSLP incidence by age, sex, region of origin, income, partner or child death, birth period, and sensory impairments. RESULTS: We identified 14 977 cases and an overall incidence of 37.7 per 100 000 person-years at-risk (95% CI = 37.1-38.3), with evidence that rates increased more sharply with age for women (likelihood ratio test: χ2(6) = 31.56, P < .001). After adjustment for confounders, rates of VLOSLP were higher among migrants from Africa (hazard ratio [HR] = 2.0, 95% CI = 1.4-2.7), North America (HR = 1.4, 95% CI = 1.0-1.9, P = .04), Europe (HR = 1.3, 95% CI = 1.2-1.4), Russian-Baltic regions (HR = 1.6, 95% CI = 1.4-1.9), and Finland (HR = 1.6, 95% CI = 1.5-1.7). VLOSLP risk was highest for those in the lowest income quartile (HR = 3.1, 95% CI = 2.9-3.3). Rates were raised in those whose partner died 2 years before cohort exit (HR = 1.1, 95% CI = 1.0-1.3, P = .02) or whose child died in infancy (HR = 1.2, 95% CI = 1.0-1.4, P = .05), those without a partner (HR = 1.9, 95% CI = 1.8-1.9) or children (HR = 2.4, 95% CI = 2.3-2.5), and those whose child had a psychotic disorder (HR = 2.4, 95% CI = 2.2-2.6). INTERPRETATION: We identified a substantial burden of psychosis incidence in old age, with a higher preponderance in women and most migrant groups. Life course exposure to environmental factors including markers of deprivation, isolation, and adversity were associated with VLOSLP risk.

The incidence of very late-onset psychotic disorders: a systematic review and meta-analysis, 1960-2016.

A substantial subset of people with psychotic disorders are first diagnosed in old age, yet little is known about the epidemiology of very late-onset schizophrenia-like psychosis. We investigated the incidence of affective and non-affective psychotic disorders in those aged 65 and above, and examined variation related to potential risk factors via systematic literature review. We searched PubMed, PsychInfo, Web of Science and bibliographies and directly contacted authors to obtain citations published between 1960 and 2016 containing (derivable) incidence data. Cases were those diagnosed with non-organic psychotic disorders after age 65. Findings were presented narratively, and random-effects meta-analyses were used to obtain pooled incidence rates. From 5687 citations, 41 met inclusion criteria. The pooled incidence of: affective psychoses was 30.9 per 100 000 person-years at risk (100 kpy) [95% confidence interval (CI) 11.5-83.4; I2 = 0.99], and schizophrenia was 7.5 per 100 kpy (95% CI 6.2-9.1; I2 = 0.99), with some evidence of higher schizophrenia rates in women [odds ratio (OR) = 1.6; 95% CI 1.0-2.5, p = 0.05]. We found narrative evidence of increasing incidence rates of non-affective psychoses with age, and higher rates amongst migrants than baseline populations, but no evidence that incidence varied by study quality or case ascertainment period (quality OR = 1.04; 95% CI 0.74-1.48; time period OR = 1.00; 95% CI 0.95-1.05). Substantial heterogeneity in the incidence of very late-onset schizophrenia-like psychoses was observed. No identified studies examined possible risk factors which may account for such variation, including socio-economic status, sensory impairment, traumatic life events, or social isolation.