Dementia Risk Prediction: Are We There Yet?

Multi-domain prognostic models used in middle-aged adults without known cognitive impairment for predicting subsequent dementia

BACKGROUND

Dementia, a global health priority, has no current cure. Around 50 million people worldwide currently live with dementia, and this number is expected to treble by 2050. Some health conditions and lifestyle behaviours can increase or decrease the risk of dementia and are known as 'predictors'. Prognostic models combine such predictors to measure the risk of future dementia. Models that can accurately predict future dementia would help clinicians select high-risk adults in middle age and implement targeted risk reduction.

OBJECTIVES

Our primary objective was to identify multi-domain prognostic models used in middle-aged adults (aged 45 to 65 years) for predicting dementia or cognitive impairment. Eligible multi-domain prognostic models involved two or more of the modifiable dementia predictors identified in a 2020 Lancet Commission report and a 2019 World Health Organization (WHO) report (less education, hearing loss, traumatic brain injury, hypertension, excessive alcohol intake, obesity, smoking, depression, social isolation, physical inactivity, diabetes mellitus, air pollution, poor diet, and cognitive inactivity). Our secondary objectives were to summarise the prognostic models, to appraise their predictive accuracy (discrimination and calibration) as reported in the development and validation studies, and to identify the implications of using dementia prognostic models for the management of people at a higher risk for future dementia.

SEARCH METHODS

We searched MEDLINE, Embase, PsycINFO, CINAHL, and ISI Web of Science Core Collection from inception until 6 June 2022. We performed forwards and backwards citation tracking of included studies using the Web of Science platform.  SELECTION CRITERIA: We included development and validation studies of multi-domain prognostic models. The minimum eligible follow-up was five years. Our primary outcome was an incident clinical diagnosis of dementia based on validated diagnostic criteria, and our secondary outcome was dementia or cognitive impairment determined by any other method.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references, extracted data using a template based on the CHecklist for critical Appraisal and data extraction for systematic Reviews of prediction Modelling Studies (CHARMS), and assessed risk of bias and applicability of included studies using the Prediction model Risk Of Bias ASsessment Tool (PROBAST). We synthesised the C-statistics of models that had been externally validated in at least three comparable studies.  MAIN RESULTS: We identified 20 eligible studies; eight were development studies and 12 were validation studies. There were 14 unique prognostic models: seven models with validation studies and seven models with development-only studies. The models included a median of nine predictors (range 6 to 34); the median number of modifiable predictors was five (range 2 to 11). The most common modifiable predictors in externally validated models were diabetes, hypertension, smoking, physical activity, and obesity. In development-only models, the most common modifiable predictors were obesity, diabetes, hypertension, and smoking. No models included hearing loss or air pollution as predictors. Nineteen studies had a high risk of bias according to the PROBAST assessment, mainly because of inappropriate analysis methods, particularly lack of reported calibration measures. Applicability concerns were low for 12 studies, as their population, predictors, and outcomes were consistent with those of interest for this review. Applicability concerns were high for nine studies, as they lacked baseline cognitive screening or excluded an age group within the range of 45 to 65 years. Only one model, Cardiovascular Risk Factors, Ageing, and Dementia (CAIDE), had been externally validated in multiple studies, allowing for meta-analysis. The CAIDE model included eight predictors (four modifiable predictors): age, education, sex, systolic blood pressure, body mass index (BMI), total cholesterol, physical activity and APOEƐ4 status. Overall, our confidence in the prediction accuracy of CAIDE was very low; our main reasons for downgrading the certainty of the evidence were high risk of bias across all the studies, high concern of applicability, non-overlapping confidence intervals (CIs), and a high degree of heterogeneity. The summary C-statistic was 0.71 (95% CI 0.66 to 0.76; 3 studies; very low-certainty evidence) for the incident clinical diagnosis of dementia, and 0.67 (95% CI 0.61 to 0.73; 3 studies; very low-certainty evidence) for dementia or cognitive impairment based on cognitive scores. Meta-analysis of calibration measures was not possible, as few studies provided these data.

AUTHORS' CONCLUSIONS

We identified 14 unique multi-domain prognostic models used in middle-aged adults for predicting subsequent dementia. Diabetes, hypertension, obesity, and smoking were the most common modifiable risk factors used as predictors in the models. We performed meta-analyses of C-statistics for one model (CAIDE), but the summary values were unreliable. Owing to lack of data, we were unable to meta-analyse the calibration measures of CAIDE. This review highlights the need for further robust external validations of multi-domain prognostic models for predicting future risk of dementia in middle-aged adults.

Cognitive Function and Vascular Risk Factors Among Older African American Adults

To evaluate the association between vascular risk factors and cognitive impairment among older African American (AA) adults in a primary care clinic. Participants included 96 AA adults aged 60 years or older who were evaluated for global and domain-specific cognition. Participants were interviewed using the Computerized Assessment of Memory and Cognitive Impairment (CAMCI). The relationship between CAMCI cognitive domain scores and vascular risk factors were examined using hierarchical regression models. Patients who smoked, those with higher SBP/DBP values had lower accuracy rates on CAMCI cognitive domains (attention, executive, memory).Those with higher BMI had better attention scores. Patients with higher HbA1C values had worse verbal memory. Patients with higher blood pressure were significantly faster in responding to tasks in the executive domain. Primary care providers working with older AA adults with these VRFs could implement cognitive screening earlier into their practice to reduce barriers of seeking treatment.

Antemortem Prediction of Braak Stage

We examined the extent to which tauopathy distribution, as determined by Braak staging, might be predicted by various risk factors in older individuals. The Swedish Twin Registry provided extensive information on neuropsychological function, lifestyle, and cardiovascular risk factors of 128 patients for whom autopsy data including Braak staging were available. Logistic regression was used to develop a prognostic model that targeted discrimination between Braak stages 0 to II and III to VI. The analysis showed that Braak stages III to VI were significantly predicted by having 1 or more APOE ε4 alleles, older age, high total cholesterol, absence of diabetes and cardiovascular disease, and poorer scores on the Wechsler Adult Intelligence Score Information test, verbal fluency, and recognition memory but better verbal recall. The algorithm predicted Braak stages III to VI well (receiver-operating characteristic area under curve, 0.897; 95% confidence interval, 0.842-0.951). Using a cutoff of 50% risk or more, the sensitivity was 85%, the specificity was 70%, and the negative predictive value was 69%. This study demonstrates that tauopathy distribution can be accurately predicted using a combination of antemortem patient data. These results provide further insight into tauopathy development and AD-related disease mechanisms and suggest a prognostic model that predicts the spread of neurofibrillary tangles above the transentorhinal stage.

The association between health literacy and indicators of cognitive impairment in a diverse sample of primary care patients

OBJECTIVES

To confirm the association of health literacy scores as measured by Health Literacy Assessment Using Talking Touchscreen Technology (Health LiTT) with cognitive ability and education. To determine whether this association differs by cognitive task.

METHODS

Cognitive impairment was measured using the Mini-Cog, which combines a delayed word recall task (WRT) and a clock drawing task (CDT) to yield an overall classification of normal versus cognitively impaired. Participants were recruited from primary care clinics that provide care to underserved patients.

RESULTS

Participants (n=574) were predominantly non-Hispanic black (67%) with a mean age of 46 years, 50% did not have health insurance, 56% had a high school education or less and 21% screened positive for cognitive impairment. Overall cognitive ability and education were significantly associated with health literacy after adjusting for other variables, including race/ethnicity and physical health. We observed a stronger association between the CDT and health literacy than between the WRT and health literacy.

CONCLUSION

By confirming hypothesized associations, this study provides additional support of the validity of Health LiTT.

PRACTICE IMPLICATIONS

Health LiTT is a reliable and valid tool that researchers and clinicians can use to identify individuals who might have difficulty understanding health information.

Cognitive frailty: rational and definition from an (I.A.N.A./I.A.G.G.) international consensus group

The frailty syndrome has recently attracted attention of the scientific community and public health organizations as precursor and contributor of age-related conditions (particularly disability) in older persons. In parallel, dementia and cognitive disorders also represent major healthcare and social priorities. Although physical frailty and cognitive impairment have shown to be related in epidemiological studies, their pathophysiological mechanisms have been usually studied separately. An International Consensus Group on "Cognitive Frailty" was organized by the International Academy on Nutrition and Aging (I.A.N.A) and the International Association of Gerontology and Geriatrics (I.A.G.G) on April 16th, 2013 in Toulouse (France). The present report describes the results of the Consensus Group and provides the first definition of a "Cognitive Frailty" condition in older adults. Specific aim of this approach was to facilitate the design of future personalized preventive interventions in older persons. Finally, the Group discussed the use of multidomain interventions focused on the physical, nutritional, cognitive and psychological domains for improving the well-being and quality of life in the elderly. The consensus panel proposed the identification of the so-called "cognitive frailty" as an heterogeneous clinical manifestation characterized by the simultaneous presence of both physical frailty and cognitive impairment. In particular, the key factors defining such a condition include: 1) presence of physical frailty and cognitive impairment (CDR=0.5); and 2) exclusion of concurrent AD dementia or other dementias. Under different circumstances, cognitive frailty may represent a precursor of neurodegenerative processes. A potential for reversibility may also characterize this entity. A psychological component of the condition is evident and concurs at increasing the vulnerability of the individual to stressors.

The accuracy of family physicians' dementia diagnoses at different stages of dementia: a systematic review

OBJECTIVE

Optimising care for dementia patients and their informal carers is imperative in light of the impending dementia epidemic. An important aspect of care is accurate recognition and diagnosis of dementia. The aim of this review was to estimate family physicians' diagnostic accuracy at the different stages of dementia.

METHODS

Pubmed, Embase, CINAHL, PsycINFO and the Cochrane Library were searched for articles comparing family physicians' 'dementia' and 'cognitive impairment' diagnoses in the primary care setting to reference standard dementia diagnoses.

RESULTS

Data from six cross-sectional studies of moderate to reasonable methodological quality were extracted for the analysis. One study considered the accuracy of family physicians' recollected diagnoses, and three studies focussed on documented diagnoses. In these four studies, the sensitivity of family physicians' combined diagnostic categories of 'cognitive impairment' together with 'dementia' was 0.48-0.67 for mild dementia and 0.76-0.85 for moderate to severe dementia. The sensitivity of their diagnostic category 'dementia' alone was 0.14-0.33 for mild and 0.28-0.61 for moderate to severe dementia. Specificity was excellent for all severity stages in both comparisons. Three studies examined the accuracy of family physicians' judgement of cognition during consultation. Compared with the studies on recollection and documentation, these studies reported higher sensitivity and lower specificity.

CONCLUSION

Many individuals with dementia are not recognised or not diagnosed as such; particularly mild dementia is under-diagnosed. Collaboration within primary care and education focussing both on knowledge and attitude are recommended to improve the accuracy of family physicians' dementia diagnosis.

Dementia: opportunities for risk reduction and early detection in general practice

This project aimed to measure general practitioner (GP), practice nurse and patient health literacy about memory problems, dementia and its risk factors. Data were collected from general practices across Australia and a smaller sample in England. Questionnaires explored sources and adequacy of dementia knowledge and a randomised controlled trial tested the intervention of a dementia risk reduction pamphlet on patient knowledge of dementia risk reduction strategies. Data were analysed using SPSS software. The results of 621 questionnaires from patients aged over 30 years showed 37% had memory concerns, 6% recalled having a memory test, 52% would like a memory test and 15% had heard about dementia from their GP. Patients receiving the intervention were significantly more likely to be aware of dementia risk reduction strategies (P≤0.005). The results of 153 GP/nurse questionnaires indicated 64% thought a doctor should discuss dementia with patients despite only 21% assessing their dementia knowledge as adequate. There was no significant difference in responses between Australia and England (P≥0.05). The frequency of documentation of Mini-Mental State Examination and dementia diagnosis in computerised medical records of patients over 75 years was less than 0.01. These results demonstrate that many adult patients attending GPs have memory concerns, associate dementia with memory loss, and are receptive to information about dementia risk reduction. Most general practitioners and their nurses rate their dementia knowledge as inadequate with few testing for memory problems or discussing dementia with their patients.

Nontraditional risk factors combine to predict Alzheimer disease and dementia

OBJECTIVE

To investigate whether dementia risk can be estimated using only health deficits not known to predict dementia.

METHODS

A frailty index consisting of 19 deficits not known to predict dementia (the nontraditional risk factors index [FI-NTRF]) was constructed for 7,239 cognitively healthy, community-dwelling older adults in the Canadian Study of Health and Aging. From baseline, their 5-year and 10-year risks for Alzheimer disease (AD), dementia of all types, and survival were estimated.

RESULTS

The FI-NTRF was closely correlated with age (r2 > 0.96, p < 0.001). The incidence of AD and dementia increased exponentially with the FI-NTRF (r2 > 0.75, p < 0.001 over 10 years). Adjusted for age, sex, education, and baseline cognition, the odds ratio of dementia increased by 3.2% (p = 0.021) for each deficit (that was not known to predict dementia) accumulated, outperforming the individual cognitive risk factors. The FI-NTRF discriminated people with AD and all-cause dementia from those who were cognitively healthy with an area under the receiver operating characteristic curve of 0.66 ± 0.03.

CONCLUSIONS

Comprehensive re-evaluation of a well-characterized cohort showed that age-associated decline in health status, in addition to traditional risk factors, is a risk factor for AD and dementia. General health may be an important confounder to consider in dementia risk factor evaluation. If a diverse range of deficits is associated with dementia, then improving general health might reduce dementia risk.

Revitalizing the aged brain

Optimal cognitive and emotional function is vital to independence, productivity, and quality of life. Cognitive impairment without dementia may be seen in 16% to 33% of adults older than 65 years, and is associated with significant emotional distress. Cognitive and emotional well-being are inextricably linked. This article qualifies revitalizing the aged brain, discusses neuroplasticity, and suggests practical neuroplasticity-based strategies to improve the cognitive and emotional well-being of older adults.