Cognitive dysfunction, including mild cognitive impairment and dementia, is increasingly recognised as an important comorbidity and complication of diabetes that affects an individual's well-being and diabetes management, and is associated with diabetes treatment-related complications. Recent guidelines therefore recommend screening for cognitive impairment in older individuals with diabetes. In addition, these guidelines suggest that glucose-lowering treatment should be tailored in those diagnosed with cognitive impairment, to reduce the risk of hypoglycaemia and improve treatment adherence. This review gives an overview of cognitive dysfunction in people with diabetes, briefly describing the clinical features of different stages of cognitive dysfunction and their epidemiology. In particular, it addresses essential additional steps that need to be taken to fully implement the emerging guidelines on screening and management of cognitive dysfunction in diabetes into daily practice.

Dementia is a major cause of disability and death among older adults. Those with type 2 diabetes (T2D) are 50-100% more likely to develop dementia than those without T2D, but it is unknown whether this association reflects a causal relationship. Proposed mechanisms through which T2D could cause dementia include the effects of insulin dysregulation and chronic hyperglycemia on features of Alzheimer's disease and macrovascular and microvascular disorders in the brain. More research is needed to elucidate the link between T2D and dementia and identify strategies to maintain cognitive function among people with T2D.

Objective

Depression afflicts 14% of individuals with type 1 diabetes (T1D). Depression is a robust risk factor for dementia but it is unknown if this holds true for individuals with T1D, who recently started living to an age conferring dementia risk. We examined if depression is a dementia risk factor among elderly individuals with T1D.

Methods

3,742 individuals with T1D age ≥50 were followed for dementia from 1/1/96-9/30/2015. Depression, dementia, and comorbidities were abstracted from electronic medical records. Cox proportional hazard models estimated the association between depression and dementia adjusting for demographics, glycosylated hemoglobin, severe dysglycemic epidsodes, stroke, heart disease, nephropathy, and end stage renal disease. The cumulative incidence of dementia by depression was estimated conditional on survival dementia-free to age 55.

Results

Five percent (N = 182) were diagnosed with dementia and 20% had baseline depression. Depression was associated with a 72% increase in dementia (fully adjusted HR = 1.72; 95% CI:1.12-2.65). The 25-year cumulative incidence of dementia was more than double for those with versus without depression (27% vs. 12%).

Conclusions

For people with T1D, depression significantly increases dementia risk. Given the pervasiveness of depression in T1D, this has major implications for successful aging in this population recently living to old age.

Background

Asian Americans are a rapidly growing and diverse population. Prior research on dementia among Asian Americans focused on Japanese Americans or Asian Americans overall, although marked differences in cardiometabolic conditions between subgroups have been documented.

Materials and methods

We compared dementia incidence among 4 Asian American subgroups (n=8384 Chinese; n=4478 Japanese; n=6210 Filipino; n=197 South Asian) and whites (n=206,490) who were Kaiser Permanente Northern California members aged 64 years and above with no dementia diagnoses as of January 1, 2000. Dementia diagnoses were collected from medical records January 1, 2000 to December 31, 2013. Baseline medical utilization and comorbidities (diabetes, depression, hypertension, stroke, cardiovascular disease) were abstracted from medical records January 1, 1996 to December 31, 1999. We calculated age-standardized dementia incidence rates and Cox models adjusted for age, sex, medical utilization, and comorbidities.

Results

Mean baseline age was 71.7 years; mean follow-up was 9.6 years. Age-standardized dementia incidence rates were higher among whites than "All Asian-Americans" or any subgroup. Compared with Chinese (13.7/1000 person-years), dementia incidence was slightly higher among Japanese [14.8/1000 person-years; covariate-adjusted hazard ratio (adjusted-HR)=1.08; 95% confidence interval (CI), 0.99-1.18] and Filipinos (17.3/1000 person-years; adjusted-HR=1.20; 95% CI, 1.11-1.31), and lower among South Asians (12.1/1000 person-years; adjusted-HR=0.81; 95% CI, 0.53-1.25).

Conclusions

Future studies are needed to understand how immigration history, social, environmental, and genetic factors contribute to dementia risk in the growing and diverse Asian American population.

Objective

Individuals with type 1 diabetes have experienced an increase in life expectancy, yet it is unknown what level of glycemic control is ideal for maintaining late-life brain health. We investigated the association of long-term glycemic control with dementia in older individuals with type 1 diabetes.

Research design and methods

We followed 3,433 members of a health care system with type 1 diabetes, aged ≥50 years, from 1996 to 2015. Repeated measurements of hemoglobin A_1c (HbA_1c), dementia diagnoses, and comorbidities were ascertained from health records. Cox proportional hazards models were fit to evaluate the association of time-varying glycemic exposure with dementia, with adjustment for age, sex, race/ethnicity, baseline health conditions, and frequency of HbA_1c measurement.

Results

Over a mean follow-up of 6.3 years, 155 individuals (4.5%) were diagnosed with dementia. Patients with ≥50% of HbA_1c measurements at 8-8.9% (64-74 mmol/mol) and ≥9% (≥75 mmol/mol) had 65% and 79% higher risk of dementia, respectively, compared with those with <50% of measurements exposed (HbA_1c 8-8.9% adjusted hazard ratio [aHR] 1.65 [95% CI 1.06, 2.57] and HbA_1c ≥9% aHR 1.79 [95% CI 1.11, 2.90]). By contrast, patients with ≥50% of HbA_1c measurements at 6-6.9% (42-52 mmol/mol) and 7-7.9% (53-63 mmol/mol) had a 45% lower risk of dementia (HbA_1c 6-6.9% aHR 0.55 [95% CI 0.34, 0.88] and HbA_1c 7-7.9% aHR 0.55 [95% CI 0.37, 0.82]).

Conclusions

Among older patients with type 1 diabetes, those with majority exposure to HbA_1c 8-8.9% and ≥9% had increased dementia risk, while those with majority exposure to HbA_1c 6-6.9% and 7-7.9% had reduced risk. Currently recommended glycemic targets for older patients with type 1 diabetes are consistent with healthy brain aging.

Study objective

The objective was to examine the association between sleep quality and global and domain-specific cognitive function among older individuals with type 1 diabetes (T1D).

Methods

We evaluated 695 individuals with T1D aged 60 years or above who participated in the baseline assessment of the Study of Longevity in Diabetes (SOLID), which captured subjective sleep quality (Pittsburgh Sleep Quality Index) and global and domain-specific (language, executive function, episodic memory, and simple attention) cognitive function. Multivariable linear regressions estimated the associations between sleep quality quartiles and overall and domain-specific cognitive function adjusting for age, sex, race/ethnicity, education, depressive symptoms, and severe hypoglycemic episodes. Sensitivity analyses examined the associations between aspects of sleep quality and global cognitive function.

Results

The worst sleep quality quartile was associated with lower global cognition (β=-0.08; 95% confidence interval: -0.17, -0.01) and lower executive function (β=-0.17, 95% confidence interval: -0.30, -0.03) compared with the best quartile of sleep quality adjusting for demographics and comorbidities. Sleep quality was not associated with language, episodic memory, or simple attention. Sleep medications and daytime dysfunction were most strongly associated with global cognition.

Conclusion

Our results suggest that sleep quality may be a modifiable risk factor for global cognitive function and executive function among elderly individuals with T1D.

Background

Poor pulmonary function (PPF) is associated with increased risk of dementia, yet it is unclear if PPF in early adulthood to midlife increases risk, independent of smoking and subsequent vascular disease.

Objective

This study evaluated the association between multiple markers of PPF in early adulthood to midlife and long-term risk of dementia.

Methods

We evaluated 27,387 members of an integrated health care system with forced expiratory volume in 1, 2 seconds, and vital capacity collected from 1964 to 1973 (mean age=41.8±4.2 y). Associations of PPF with dementia diagnoses from January 1, 1996 to September 30, 2015 were evaluated with Cox proportional hazards models adjusted for demographics, height, body mass index, hypertension, smoking status, diabetes, stroke, and heart failure.

Results

In total, 7519 individuals (27%) were diagnosed with dementia. In fully adjusted Cox proportional hazards models, for all PPF measures each liter decrease was associated with a 13% to 14% higher risk of dementia. Compared with the highest quintile, the first quintile of PPF measures were associated with a 24% to 28% increased risk of dementia; second to fourth quintiles showed strong dose-dependent associations. Results were similar when stratified by smoking status.

Conclusions

In this large, diverse cohort, multiple measures of PPF in early adulthood to midlife were associated with dementia risk independent of smoking and vascular comorbidities.

Background

Posttraumatic stress disorder is associated with increased dementia risk but less is known about stress because of everyday problems in diverse populations.

Methods

A total of 9605 health care plan members who provided information regarding midlife stressors in 1972 to 1973 (ages, 40 to 55 y) were followed for dementia diagnosis between 1996 and 2017. Cox proportional hazard models evaluated associations between midlife stressors and dementia adjusting for demographics and lifecourse health indicators.

Results

Reporting at least 1 midlife stressor was associated with 17% greater dementia risk [hazard ratio (HR), 1.17; 95% confidence interval (CI),1.07-1.27] versus 0 midlife stressors and 26% increased risk among those with less than equal to high school education (HR, 1.26; 95% CI,1.09-1.44) adjusting for demographics. Compared with whites without stressors, whites with ≥1 stressor had 13% greater dementia risk (HR, 1.13; 95% CI, 1.02-1.24), blacks without stressors 19% greater risk (HR, 1.19; 95% CI,1.08-1.32), and blacks with ≥1 stressors 47% greater risk (HR, 1.47; 95% CI,1.27-1.69) in fully adjusted models. Resource problems were associated with 20% greater risk (HR, 1.20; 95% CI, 1.01-1.42) than interpersonal problems.

Conclusion

Reporting ≥1 serious midlife stressor was associated with elevated dementia risk, especially stressors related to resources problems and for those with less than equal to high school education. Everyday stressors can impact brain health over the long term and may contribute to racial inequities in dementia rates, though education can be a mitigating factor.