A population-based study of the association between coronary artery bypass graft surgery (CABG) and cognitive decline: the Cache County study

Cognition and Exercise: GENERAL OVERVIEW AND IMPLICATIONS FOR CARDIAC REHABILITATION

Performance of endurance exercise is associated with a broad range of cognitive benefits, with notable improvements shown across a wide variety of populations including healthy populations as well as those with impaired cognition. By examining the effects of exercise in general populations, as well in populations where cognitive deficits are pronounced, and critical to self-care, we can learn more about using exercise to ameliorate cognitive issues and apply that knowledge to other patient populations, such as those eligible for cardiac rehabilitation (CR). Cognitive challenges are a concern within CR, as management of a chronic disease is cognitively taxing, and, as expected, deficits in cognition predict worse outcomes, including lower attendance at CR. Some subsets of patients within CR may be particularly at high risk for cognitive challenges including those with heart failure with low ejection fraction, recent coronary bypass surgery, multiple chronic conditions, and patients of lower socioeconomic status. Attendance at CR is associated with cognitive gains, likely through the progressive exercise component, with larger amounts of exercise over longer periods having greater benefits. Programs should identify at-risk patients, who could gain the most from completing CR, and provide additional support to keep those patients engaged. While engaged in CR, patients should be encouraged to exercise, at least at moderate intensity, and transitioned to a long-term exercise regimen. Overall, CR programs are well-positioned to support these patients and make significant contributions to their long-term well-being.

Predictors of cognitive dysfunction after cardiac surgery: a systematic review

AIMS

Postoperative cognitive dysfunction (POCD) is often experienced by cardiac surgery patients; however, it is not known if some groups of patients experience this more frequently or severely than others.The aim of this systematic review was to identify preoperative and postoperative predictors of cognitive dysfunction in adults following cardiac surgery.

METHODS AND RESULTS

Eight bibliographic databases were searched (January 2005 to March 2021) in relation to cardiac surgery and cognition. Studies including adult patients who had undergone open cardiac surgery and using a validated measurement of cognitive function were included. Full-text review for inclusion, quality assessment, and data extraction were undertaken independently by two authors.A total of 2870 papers were identified, of which 36 papers met the inclusion criteria and were included in the review. The majority were prospective observational studies [n = 28 (75.7%)]. In total, 61 independent predictors (45 preoperative and 16 postoperative) were identified as significant in at least one study; advancing age and education level appear important. Age has emerged as the most common predictor of cognitive outcome.

CONCLUSION

Although a number of predictors of POCD have been identified, they have inconsistently been reported as significantly affecting cognitive outcome. Consistent with previous research, our findings indicate that older patients and those with lower educational levels should be prioritized when developing and trialling interventions to improve cognitive function. These findings are less than surprising if we consider the methodological shortcomings of included studies. It is evident that further high-quality research exploring predictors of POCD is required.

The state of cognitive function in patients with stable coronary artery disease after coronary artery bypass grafting

Aim      To study the cognitive function (CF) state in patients with chronic ischemic heart disease (IHD) depending on the method of coronary bypass (CB), with extracorporeal circulation (EC) or on beating heart.Material and methods  Postoperative cognitive dysfunction (POCD) is a frequent complication of CB, and its development may depend on the method of surgery, with EC or on beating heart. This single-center, prospective, nonrandomized study included 196 patients with chronic IHD aged 61.0±5.1 years. Patients were divided into two groups based on the CB method: an EC group (n=11) and a beating heart surgery group (n=85). Mean follow-up period was 26±2.1 mos. The state of CF was evaluated before and after CB (at the hospital stage, at 3, 6, 12, and 24 mos.).Results The mean duration of CF recovery was 3 mos. only in the group of CB without EC (p<0.05), whereas after CB with EC, CF parameters were similar to those during the hospital stage with somewhat reduced values. In 6 mos. after CB, CF normalized to baseline values in both groups (with and without EC). A possible CF decline in patients with chronic IHD after CB depended on the following factors: age older than 60 years (p<0.05), diabetes mellitus with glycated hemoglobin >7.5 % (p=0.001) and 6.5-7.5 % (p=0.03), smoking (p=0.04), atherosclerotic damage of the internal carotid artery (p<0.05), and a Charlson comorbidity index >5 (p=0.03). The CB surgery either with EC (p=0.04) or on beating heart (p=0.04) was associated with the development of CD.Conclusion      The results of the study allow identifying patients with chronic IHD and POCD-predisposing factors to recommend them beathing heart CB surgery.

The risk of dementia after coronary artery bypass grafting in relation to age and sex

Introduction

We examined the long‐term risk of dementia after coronary artery bypass grafting (CABG) in relation to age and sex.

Methods

All CABG patients in Sweden 1992–2015 (n = 111,335), and matched controls (n = 222,396) were included in a population‐based study. Adjusted hazard ratios (aHR) for all‐cause dementia, vascular dementia, and Alzheimer's disease were calculated.

Results

There was no difference in the risk for all‐cause dementia between CABG patients and control subjects (aHR 0.98 [95% confidence interval 0.95 to 1.02]). CABG patients <65 years and 65 to 74 years had higher risk (aHR 1.29 [1.17–1.42] and 1.08 [1.02–1.13], respectively), and patients ≥75 years had lower risk (aHR 0.76 [0.71–0.81]). The highest risk was observed in women <65 years (aHR 1.64 [1.31–2.05]).

Discussion

Overall, the long‐term risk for all‐cause dementia does not differ between CABG patients and the general population. Younger patients have a higher risk, while older patients have a lower risk, compared to controls.

Coronary Artery Bypass Graft Surgery and Dementia Risk in the Cardiovascular Health Study

Supplemental Digital Content is available in the text.

Introduction:

The association between history of coronary artery bypass graft surgery (CABG) and dementia risk remains unclear.

Methods:

We conducted a prospective cohort analysis using data on 3155 elderly adults free from prevalent dementia from the US population-based Cardiovascular Health Study (CHS) with adjudicated incident all-cause dementia, Alzheimer disease (AD), vascular dementia (VaD), and mixed dementia.

Results:

In the CHS, the hazard ratio (HR) for all-cause dementia was 1.93 [95% confidence interval (CI), 1.36-2.74] for those with CABG history compared with those with no CABG history after adjustment for potential confounders. Similar HRs were observed for AD (HR=1.71; 95% CI, 0.98-2.98), VaD (HR=1.42; 95% CI, 0.56-3.65), and mixed dementia (HR=2.73; 95% CI, 1.55-4.80). The same pattern of results was observed when these CHS findings were pooled with a prior prospective study, the pooled HRs were 1.96 (95% CI, 1.42-2.69) for all-cause dementia, 1.71 (95% CI, 1.04-2.79) for AD and 2.20 (95% CI, 0.78-6.19) for VaD.

Discussion:

Our results suggest CABG history is associated with long-term dementia risk. Further investigation is warranted to examine the causal mechanisms which may explain this relationship or whether the association reflects differences in coronary artery disease severity.

Surgery upregulates high mobility group box-1 and disrupts the blood-brain barrier causing cognitive dysfunction in aged rats

AIM

Postoperative cognitive dysfunction (POCD) is a growing and largely underestimated problem without defined etiology. Herein, we sought to determine the relationship between cognitive decline, blood-brain barrier (BBB) permeability, and inflammation, namely high mobility group box-1 (HMGB1), after surgery in aged rats.

METHODS

Aged rats were randomly assigned as surgery group (n = 45, splenectomy under general anesthesia), anesthesia (n = 45, 2% isoflurane for 2 h), and naïve control (n = 15). Markers of inflammation were measured in plasma and brain. Blood-brain barrier ultrastructure and permeability were measured by transmission electron microscope (TEM) and IgG immunohistochemistry. Cognitive function was assessed in a reversal learning version of the Morris water maze (MWM).

RESULTS

Surgical trauma under general anesthesia caused distinct changes in systemic and central proinflammatory cytokines. Levels of HMGB1 and the receptor for advanced glycation end products (RAGE) were significantly upregulated in the hippocampus of operated animals. Immunohistochemistry and TEM showed BBB disruption induced by surgery and anesthesia. These molecular changes were associated with cognitive impairment in latency with the MWM up to postoperative day 3.

CONCLUSIONS

HMGB1 and RAGE signaling appear pivotal mediators of surgery-induced cognitive decline and may contribute to the changes in BBB permeability after peripheral surgical trauma.

Epidemiology of cognitive aging and Alzheimer's disease: contributions of the cache county utah study of memory, health and aging

Epidemiological studies of Alzheimer's disease (AD) provide insights into changing public health trends and their contribution to disease incidence. The current chapter considers how the population-based approach has contributed to our understanding of lifetime exposures that contribute to later disease risk and may act to modify onset of symptoms. We focus on the findings from a recent survey of an exceptionally long-lived population, the Cache County Utah Study of Memory, Health, and Aging. This study is confined to a single geographic population has allowed estimation of the genetic and environmental influences on AD expression across the expected human lifespan of 95+ years. Given the emphasis of this text on the behavioral neurosciences of aging, we highlight within the current chapter the particular contributions of this population-based study to the neuropsychology of aging and AD. We also discuss hypotheses generated from this survey with respect to factors that may either accelerate or delay symptom onset in AD and the conditions that appear to be associated with successful cognitive aging.

Review: cerebral microvascular pathology in ageing and neurodegeneration

This review of age-related brain microvascular pathologies focuses on topics studied by this laboratory, including anatomy of the blood supply, tortuous vessels, venous collagenosis, capillary remnants, vascular density and microembolic brain injury. Our studies feature thick sections, large blocks embedded in celloidin, and vascular staining by alkaline phosphatase. This permits study of the vascular network in three dimensions, and the differentiation of afferent from efferent vessels. Current evidence suggests that there is decreased vascular density in ageing, Alzheimer's disease and leukoaraiosis, and cerebrovascular dysfunction precedes and accompanies cognitive dysfunction and neurodegeneration. A decline in cerebrovascular angiogenesis may inhibit recovery from hypoxia-induced capillary loss. Cerebral blood flow is inhibited by tortuous arterioles and deposition of excessive collagen in veins and venules. Misery perfusion due to capillary loss appears to occur before cell loss in leukoaraiosis, and cerebral blood flow is also reduced in the normal-appearing white matter. Hypoperfusion occurs early in Alzheimer's disease, inducing white matter lesions and correlating with dementia. In vascular dementia, cholinergic reductions are correlated with cognitive impairment, and cholinesterase inhibitors have some benefit. Most lipid microemboli from cardiac surgery pass through the brain in a few days, but some remain for weeks. They can cause what appears to be a type of vascular dementia years after surgery. Donepezil has shown some benefit. Emboli, such as clots, cholesterol crystals and microspheres can be extruded through the walls of cerebral vessels, but there is no evidence yet that lipid emboli undergo such extravasation.

Central nervous system injury associated with cardiac surgery

Millions of individuals with coronary artery or valvular heart disease have been given a new chance at life by heart surgery, but the potential for neurological injury is an Achilles heel. Technological advancements and innovations in surgical and anaesthetic technique have allowed us to offer surgical treatment to patients at the extremes of age and infirmity-the group at greatest risk for neurological injury. Neurocognitive dysfunction is a complication of cardiac surgery that can restrict the improved quality of life that patients usually experience after heart surgery. With a broader understanding of the frequency and effects of neurological injury from cardiac surgery and its implications for patients in both the short term and the long term, we should be able to give personalised treatments and thus preserve both their quantity and quality of life. We describe these issues and the controversies that merit continued investigation.