Prevention of cognitive impairment: scientific guidance and windows of opportunity

Neuroanatomical and clinical factors predicting future cognitive impairment

Identifying cognitively normal (CN) older adults who will convert to cognitive impairment (CI) due to Alzheimer's disease is crucial for early intervention. Clinical and neuroimaging measures were acquired from 301 CN adults who converted to CI within 15 years of baseline, and 294 who did not. Regional volumes and brain age measures were extracted from T1-weighted magnetic resonance images. Linear discriminant analysis compared non-converters' characteristics against those of short-, mid-, and long-term converters. Conversion was associated with clinical measures such as hearing impairment and self-reported memory decline. Converters' brain volumes were smaller than non-converters' across 48 frontal, temporal, and subcortical structures. Brain age measures of 12 structures were correlated with shorter times to conversion. Conversion prediction accuracy increased from 81.5% to 90.5% as time to conversion decreased. Proximity to CI conversion is foreshadowed by anatomic features of brain aging that enhance the accuracy of predicting conversion.

What have clinical trials taught us about brain health?

The Global Burden of Disease Study projects an almost tripling of dementia cases worldwide in the next 30 years making it important to recognize and understand modifiable risks and preventatives for cognitive impairment. Recent studies suggest that prevention or treatment of cardiovascular risks may be an important strategy to prevent or slow the progression of cognitive impairment. In 2017, the American Heart Association and American Stroke Association introduced metrics for "optimal brain health". These metrics defined brain health in terms of ideal health behaviors and factors. Since then and leading up to 2017, a number of clinical trials have been conducted to investigate the potential of modification of cardiovascular risks on prevention of dementia or cognitive impairment and thus, enhancement of brain health. This discussion is a review of findings from clinical trials focusing on interventions, including antihypertensive agents, glycemic control and lipid-lowering therapies, multidomain approaches, and antithrombotic medications. Notably, the results highlight the promise of intensive blood pressure lowering strategies and multidomain approaches, as evidenced by the FINGER trial. The review also discusses the potential of treatment or prevention of cerebral small vessel disease (cSVD) and the application of Mendelian randomization as a strategy to preserve brain structure and function.

The Role of Vascular Risk Factors in Cognitive Impairment and Dementia and Prospects for Prevention

One of the most challenging clinical expressions of population aging is cognitive impairment and dementia. Among risk factors for the development of dementia, modifiable vascular risk factors have emerged as contributors to both vascular and nonvascular types of dementia. Epidemiologic studies have been particularly informative in understanding the link between vascular risks and dementia across the life course. We discuss vascular risks for dementia and cognitive impairment and practical management recommendations.

Effectiveness of dual-task computerized cognitive training in the prevention of postoperative cognitive dysfunction in coronary bypass surgery

Aim. To evaluate the effectiveness of dual-task computerized cognitive training (CCT) in the prevention of postoperative cognitive dysfunction in patients after on-pump coronary artery bypass grafting (CABG).

Material and methods. This cohort prospective study included 68 patients (median age, 64 years [54; 69]) admitted for elective on-pump CABG. In addition to the standard preoperative examination, all patients underwent advanced neuropsychological and neurophysiological examination. Starting from 3-4 days of the postoperative period, all patients underwent dual-task CCT.

Results. After 8-10 days, early postoperative cognitive dysfunction was observed in 37 (54,4%) patients from CCT group, while in patients without training in 69,3% of cases (n=79). The best results of cognitive functioning were achieved in neurodynamics and short-term memory. In addition, in patients who completed the training course, a postoperative increase in the frontooccipital gradient of theta rhythm was observed.

Conclusion. Neuropsychological and neurophysiological assessment have demonstrated the limited effectiveness of a short-term dual task CCT using in the prevention of early postoperative cognitive dysfunction in patients after on-pump CABG. The dual task method can be an additional preventive intervention in the development of a personalized approach to cognitive rehabilitation therapy in cardiac surgery patients.

Long-Term Gender-Affirming Hormone Therapy and Cognitive Functioning in Older Transgender Women Compared With Cisgender Women and Men

BACKGROUND

Long-term gender-affirming hormone therapy (GHT) in older transgender individuals could have beneficial effects on cognitive functioning. Cardiovascular risk factors and psychological factors are known determinants of cognition. Despite the rising number of older transgender individuals, only few studies have examined cognitive functioning in this population.

AIM

We aimed to assess differences in cognitive functioning between transgender women, and non-transgender (cisgender) women and men, and investigated the contribution of cardiovascular risk factors and psychological factors on these differences.

METHODS

In this study, 37 transgender women (age range 55 to 69) receiving GHT for at least ten years (range 10.2 to 41.6) were examined, and their cognitive functioning was compared to an age and education level matched cohort consisting of 222 cisgender women and men from the Longitudinal Aging Study Amsterdam. Linear regression analyses were performed.

OUTCOMES

Cognitive functioning was assessed by neuropsychological tests including Mini-Mental State Examination (MMSE), Category Fluency animals, Letter Fluency D, 15-Word test (15WT) immediate and delayed recall. Additionally, cardiovascular risk factors and psychological factors such as cardiovascular disease, hypertension, antihypertensive use, statin use, diabetes mellitus, overweight, smoking, alcohol consumption, psychopharmaceutical use, anxiety and depression symptoms were collected.

RESULTS

Transgender women had higher MMSE scores compared with cisgender women (+0.9, 95% CI 0.4 to 1.5), and cisgender men (+1.1, 95% CI 0.4 to 1.8). On all other tests transgender women performed similar to cisgender men. Transgender women performed at a lower level than cisgender women on 15WT immediate recall, -5.5, 95% CI -7.6 to -3.4, and 15WT delayed recall, -2.7, 95% CI -3.7 to -1.7, and equal to cisgender women on Fluency animals and Fluency D. Cardiovascular and psychological factors (i.e., cardiovascular disease and depression symptoms) partly explained differences on MMSE score between transgender women and cisgender-control groups.

CLINICAL IMPLICATIONS

The results of this study do not indicate a need for tailored hormone treatment strategies for older transgender women, based on cognitive aspects after long-term GHT.

STRENGTHS & LIMITATIONS

As one of the first studies, this study compared older transgender women to a large cohort of cisgender men and women regarding cognitive functioning and took into account numerous potential influencing factors. Limitations include difference in test procedures and the cross-sectional design of the study.

CONCLUSION

Cognitive differences between transgender women and cisgender women and men were small, albeit significant. This may suggest that long-term GHT effects on cognitive functioning in older transgender women are minimal. van Heesewijk JO, Dreijerink KMA, Wiepjes CM, et al. Long-Term Gender-Affirming Hormone Therapy and Cognitive Functioning in Older Transgender Women Compared With Cisgender Women and Men. J Sex Med 2021;18:1434-1443.

Retinal vessel density correlates with cognitive function in older adults

PURPOSE

We examined the associations between retinal microvascular density, cognition, and physical fitness in healthy older adults with no reported cognitive decline.

METHODS

Twenty cognitively normal older adults (age: 70.3 ± 4.6 years) were recruited. Both eyes of each subject were imaged using optical coherence tomography angiography. The vessel densities of the retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP) were measured. Cognitive function was assessed using the Mini-mental state examination (MMSE) and Montreal Cognitive Assessment (MoCA), while physical performance was evaluated using the total work during the YMCA cycle ergometer test (TW-YMCA). Spearman correlations (r_s) were computed between measures of retinal microvascular density, cognitive function, and physical performance.

RESULTS

The MoCA was significantly correlated to vessel density of SVD (r_s = 0.53, P = 0.02) but not RVN (r_s = 0.39, P = 0.09) and DVP (r_s = 0.02, P = 0.93). MoCA was not correlated with TW-YMCA (r_s = 0.05, P = 0.83). Retinal microvascular densities were not related to TW-YMCA (r_s = -0.05-0.18, P > 0.05). Additionally, MMSE was not related the retinal vessel densities (r_s = -0.10-0.21, P > 0.05) and TW-YMCA (r_s = -0.19, P = 0.41).

CONCLUSIONS

This is the first study to reveal the association between retinal vessel density and cognition as measured with MoCA in healthy older adults with no reported cognitive decline.

Neighborhood Socioeconomic Resources and Crime-Related Psychosocial Hazards, Stroke Risk, and Cognition in Older Adults

Living in neighborhoods with lower incomes, lower education/occupational levels, and/or higher crime increases one’s risk of developing chronic health problems including cardiovascular disease risk factors and stroke. These cardiovascular health problems are known to contribute to cognitive decline and dementia. The purpose of this study was to determine the association of neighborhood socioeconomic resources and crime-related psychosocial hazards on stroke risk and cognition, hypothesizing that cardiovascular health would mediate any relationship between the neighborhood-level environment and cognition. The study evaluated 121 non-demented Chicago-area adults (~67 years; 40% non-Latino White) for cardiovascular health problems using the Framingham Stroke Risk Profile 10-year risk of stroke (FSRP-10). The cognitive domains that were tested included memory, executive functioning, and attention/information processing. Neighborhood socioeconomic resources were quantified at the census tract level (income, education, and occupation); crime-related psychosocial hazards were quantified at the point level. Structural equation modeling (SEM) did not show that the FSRP-10 mediated the relationship between neighborhood characteristics and domain-specific cognition. The SEM results did suggest that higher crime rates were associated with a higher FSRP-10 (β(105) = 2.38, p = 0.03) and that higher FSRP-10 is associated with reduced attention/information processing performance (β(105) = −0.04, p = 0.02) after accounting for neighborhood socioeconomic resources. Clinicians may wish to query not only individual but also neighborhood-level health when considering cognition.

Brain Health: A Concept Analysis

The concept of brain health has been inconsistently used across disciplines. This concept analysis sought to clarify brain health and construct a unified definition that may lead to consistent use of this concept. The analysis used Walker and Avant's framework to identify scholarly reports on the concept of brain health from various electronic databases. Building on the identified data sources, brain health can be understood as the brain's ability to optimally adapt to internal and external human conditions through cognitive and emotional responses across one's lifespan, which result in sustainable positive changes in brain structures and functional features. This analysis emphasized that maintaining brain health has positive implications on an individual's lifelong quality of health, independence, and delaying cognitive decline. By clarifying uses and definitions of the concept of brain health, this concept analysis may enable researchers and clinicians to evaluate and interpret the concept related data consistently.

Characterization of retinal microvasculature and its relations to cognitive function in older people after circuit resistance training

PURPOSE

To characterize the changes of retinal microvascular density and their relations to cognitive function in the healthy older people without known cognitive impairment after an 8-week high-speed circuit resistance training program (HSCT).

METHODS

Twenty cognitively normal older people were recruited and randomly assigned to either the HSCT group or control group (CON). Twelve subjects (age 70.8 ± 5.8 yrs) in the HSCT group trained three times per week for 8 weeks. Eight subjects in the CON group (age 71.8 ± 4.8 yrs) did not perform formal training. Both eyes of each subject were imaged using optical coherence tomography angiography (OCTA) at baseline and at 8-week follow-up. The densities of the retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP) were measured. In addition, their cognitive functions were tested using the NIH toolbox.

RESULTS

There were significant increases in pattern comparison processing speed (PAT, P = 0.02) and fluid composite score (FCS, P = 0.005) at the follow-up in the HSCT group. Although the vessel densities did not differ between visits in either group, the variation (i.e., change) in retinal vessel density of SVP was negatively related to the changes of FCS (r = -0.54, P = 0.007) and the List Sorting Working Memory test (r = -0.43, P = 0.039) in the HSCT group.

CONCLUSIONS

This is the first study to reveal that the individual response of the SVD was related to the improvement in the cognition in cognitively normal older people after HSCT.

Alternate Healthy Eating Index is Positively Associated with Cognitive Function Among Middle-Aged and Older Hispanics/Latinos in the HCHS/SOL

BACKGROUND

Diet quality may be an important area of focus for promoting cognitive health; however, the association between diet quality and cognitive function among Hispanics/Latinos remains largely unexamined. We hypothesized that a healthier diet quality will be associated with better cognitive function in middle-aged and older Hispanics/Latinos.

OBJECTIVE

The objective of this study was to examine associations between the Alternate Healthy Eating Index (AHEI-2010), a measure of diet quality, and cognitive function in middle-aged and older Hispanics/Latinos.

METHODS

Data from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Visit 1 (2008-2011) were used (n = 8461; ages 45-74 y). Cognitive function was assessed with tests of verbal learning and memory, verbal fluency, and processing speed; a global cognition score was derived by summing the z scores of individual tests. Dietary intake was assessed via two 24-h recalls. Total AHEI-2010 score was categorized into quintiles (higher quintiles indicating healthier diet). Linear regression models were used to examine associations between AHEI-2010 quintiles and cognitive function adjusting for sociodemographic characteristics, daily energy intake, type 2 diabetes, smoking, and depressive symptoms.

RESULTS

Compared with the lowest quintile, in the second to fourth AHEI-2010 quintiles, global cognition scores were significantly higher by 0.28, 0.52, and 0.48 units (P-trend = 0.042). In the second to fifth AHEI-2010 quintiles, verbal learning scores were significantly higher by 0.60, 0.62, 0.92, and 0.88 units, and verbal memory scores were higher by 0.33, 0.40, 0.52, and 0.46 units (P-trend = 0.020 and 0.007, respectively). No associations were observed between the AHEI-2010 and verbal fluency or processing speed (P-trend = 0.49 and 0.84, respectively). Among AHEI-2010 components, adequate consumption of vegetables, alcohol, and whole fruits were each associated with better cognitive function.

CONCLUSIONS

An overall healthier diet quality was associated with better global cognition, verbal learning, and verbal memory in middle-aged and older Hispanics/Latinos.

Management of blood pressure in stroke

Objective

In this review and opinion piece, we discuss recent United States (US)-based guidance statements on the management of BP in stroke according to stroke type and stage of stroke.

Methods

We reviewed the most recent guidance statements on BP control from United States (US)-based organizations such as the American Heart Association/American Stroke Association (AHA/ASA) and American College of Cardiology (ACC), and articles available to the authors in their personal files.

Results

The key BP target before starting alteplase (t-PA) is < 185/110 mm Hg, and the maintenance BP after tPA administration is < 180/105 mm Hg. For IPH patients with systolic BP between 150 and 220 mm Hg and no contraindication to acute BP reduction therapy, acute lowering to 140 mm Hg systolic BP is safe. For persons with small vessel or lacunar cerebral ischemia, a reasonable BP lowering target is < 130 mm Hg systolic. For primary stroke prevention, the target BP for those with hypertension is < 140/90 mm Hg and self-measured BP is recommended to assist in BP control. Recent study and guidance suggest a BP target of <130/80 mm Hg for both primary and recurrent stroke prevention. BP control is reasonable for the prevention of cognitive decline or dementia.

Conclusions

BP targets for the proper management of stroke vary by chronological stage of stroke and by stroke subtype. Furthermore, consideration should be given to control of BP variability, especially in the acute phases of stroke, as it may play a role in conferring longer term outcomes.

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Stroke is an important cause of morbidity and mortality worldwide, and is well suited for prevention and acute treatment with proper BP management.

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BP targets in acute ischemic stroke vary whether intravenous alteplase is administered or an endovascular intervention is implemented or not.

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In acute intraparenchymal hemorrhage of the brain (IPH), it is reasonable to lower BP to a systolic level of 140–150 or up to 160 mm Hg.

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For both first and recurrent stroke prevention it is reasonable to aim for a BP target of <130/80 mm Hg based on the recent data.

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The revised BP target has been lowered to <130/80 mm Hg for prevention of major cardiovascular outcomes including stroke.

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Intensive BP control potentially preserves cognition, brain health, and brain structural integrity.

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Blood pressure variability is a new target for study in the acute treatment and prevention of stroke.

Cognitive and behavioral improvement in adults with fragile X syndrome treated with metformin-two cases

BACKGROUND

The majority of individuals with fragile X syndrome (FXS) have intellectual disability, behavioral problems, autism, and language deficits. IQ typically declines with age in boys with the full mutation. The results of preclinical studies demonstrated that metformin, a biguanide used to treat type 2 diabetes, rescues multiple phenotypes of FXS in both Drosophila and mouse models. Preliminary studies of patients with FXS demonstrated improvements in behavior.

METHODS

Here, we present two cases of individuals who have been treated with metformin clinically for one year.

RESULTS

Both patients demonstrated significant cognitive and behavioral improvements. They also improved eating habits and normalization of their weight percentiles.

CONCLUSION

Metformin may be a candidate drug for treatment of several types of symptoms in individuals with FXS.

The many faces of vascular cognitive impairment

This Preface introduces the articles of the special issue on "Vascular Dementia" in which several recognized experts provide an overview of this research field. The brain is a highly vascularized organ and consequently, vascular dysfunction and related pathways affect cognitive performance and memory. Vascular dementia or vascular cognitive impairment is the second most common type of dementia after Alzheimer's disease, and both disorders often occur in parallel. With this special issue, we hope to provide insight and a stimulating discussion for the future development of this research field. This article is part of the Special Issue "Vascular Dementia".