Work productivity loss and indirect costs associated with new cardiovascular events in high-risk patients with hyperlipidemia: estimates from population-based register data in Sweden

Self-reported mental and physical health is associated with not returning to work in patients with ischemic heart disease

BACKGROUND

Ischemic Heart Disease (IHD) can lead to prolonged sick leave and loss of ability to work. This study aimed to describe non-return to work (non-RTW) across three IHD subgroups at 3 and at 12 months post discharge, and explore whether baseline characteristics, and patient-reported mental and physical health were associated with work detachment.

METHODS

Data from the national cohort study DenHeart were used, including the patient-reported outcomes (PROs) Short-Form 12, Hospital Anxiety and Depression Scale, Edmonton Symptom Assessment Scale and HeartQoL measured at discharge and register-based follow-up at 3 and at 12 months. A total of 3873 patients with IHD ≤ 63 years old and part of the workforce prior to hospitalisation, were included in the analyses and divided into three groups: chronic IHD/stable angina, non-STEMI (non-ST-Elevation Myocardial Infarction)/unstable angina and STEMI (ST-Elevation Myocardial Infarction). A composite outcome of 'prolonged sick leave' and/or 'left the workforce' was defined as non-return to work (non-RTW). Adjusted logistic regression models were performed.

RESULTS

Overall, the frequency of non-RTW was 37.7% and 38.0% at 3 and 12 months, respectively, thus not improving with time. The largest proportion of non-RTW was found in STEMI patients, followed by non-STEMI/unstable angina and IHD/stable angina patients. Several clinical and socio-demographic factors, as well as patient-reported mental and physical health were associated with non-RTW among the subgroups.

CONCLUSION

The findings demonstrate a need for identifying IHD patients at risk of non-RTW after discharge based on their mental and physical health and a need for initiatives to minimize unwanted non-RTW.

The economic impact of stroke in Brazil, 2010-2019: Increase in public expenses of Unified Health System

OBJECTIVES

To economically analyze the impact that outpatient and inpatient spending of the Unified Health System and social security expenses of the General Regime of Social Security generated to the Brazilian public system, between 2010 and 2019.

MATERIALS AND METHODS

Observational research, in which public data from the SUS Department of Informatics and the Social Security Historical Database were used, according to 10ª International Classification of Diseases code, I-64 (Stroke, not specified if hemorrhagic or ischemic). The Kruskal-Wallis test, complemented by Dunn's post-hoc test, and Spearman's bivariate correlation test were used to check for differences and correlations between variables. The expenditures were adjusted for inflation for the year 2019 and presented in american dollar s(U$).

RESULTS

Stroke public spending impacted an average of 120 million dollars per year and increased 15% during the historical series. Eighty-nine percent of these expenditures originated from hospital spending (p<0.05). On average, stroke accounted for 7.3% of spending on cardiovascular diseases and 0.72% of spending on the other codes of 10ª International Classification of Diseases. Total spending showed a positive correlation with the historical series (r=.702; p<0.05), with the increase in the elderly population (over 60 years of age) (r=.676; p<0.05) and with Gross Domestic Product per capita (r=.784; p<0,05).

CONCLUSIONS

The impact that stroke generated on public spending increased over the historical series, mainly due to hospital spending and by the prospect of increasing elderly population in Brazil, public spending tends to rise.

The Societal Impact of Inclisiran in England: Evidence From a Population Health Approach

OBJECTIVES

As first-in-class cholesterol-lowering small interfering ribonucleic acid, inclisiran provides effective reductions in low-density lipoprotein-cholesterol to achieve better cardiovascular (CV) health. We estimate the health and socioeconomic effects of introducing inclisiran according to a population health agreement in England.

METHODS

Building on the inclisiran cost-effectiveness model, a Markov model simulates health gains in terms of avoided CV events and CV deaths because of add-on inclisiran treatment for patients aged 50 years and older with pre-existing atherosclerotic CV disease. These are translated into socioeconomic effects, defined as societal impact. To that end, we quantify avoided productivity losses in terms of paid and unpaid work productivity and monetize them according to gross value added. Furthermore, we calculate value chain effects for paid work activities, drawing on value-added multipliers based on input-output tables. The derived value-invest ratio compares avoided productivity losses against the increased healthcare costs.

RESULTS

Our results show that 138 647 CV events could be avoided over a period of 10 years. The resulting societal impact amounts to £8.17 billion, whereas additional healthcare costs are estimated at £7.94 billion. This translates into a value-invest ratio of 1.03.

CONCLUSIONS

Our estimates demonstrate the potential health and socioeconomic value of inclisiran. Thereby, we highlight the importance to treat CVD and illustrate the impact that a large-scale intervention can have on population health and the economy.

Effectiveness of eHealth Interventions Targeting Employee Health Behaviors: Systematic Review (Preprint)

BACKGROUND

The number of people with noncommunicable diseases is increasing. Noncommunicable diseases are the major cause of disability and premature mortality worldwide, associated with negative workplace outcomes such as sickness absence and reduced work productivity. There is a need to identify scalable interventions and their active components to relieve disease and treatment burden and facilitate work participation. eHealth interventions have shown potential in clinical and general populations to increase well-being and physical activity and could be well suited for workplace settings.

OBJECTIVE

We aimed to provide an overview of the effectiveness of eHealth interventions at the workplace targeting employee health behaviors and map behavior change techniques (BCTs) used in these interventions.

METHODS

A systematic literature search was performed in PubMed, Embase, PsycINFO, Cochrane CENTRAL, and CINAHL in September 2020 and updated in September 2021. Extracted data included participant characteristics, setting, eHealth intervention type, mode of delivery, reported outcomes, effect sizes, and attrition rates. Quality and risk of bias of the included studies were assessed using the Cochrane Collaboration risk-of-bias 2 tool. BCTs were mapped in accordance with the BCT Taxonomy v1. The review was reported according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist.

RESULTS

In total, 17 randomized controlled trials met the inclusion criteria. The measured outcomes, treatment and follow-up periods, content of eHealth interventions, and workplace contexts had high heterogeneity. Of the 17 studies, 4 (24%) reported unequivocally significant findings for all primary outcomes, with effect sizes ranging from small to large. Furthermore, 53% (9/17) of the studies reported mixed results, and 24% (4/17) reported nonsignificant results. The most frequently targeted behavior was physical activity (15/17, 88% of the studies); the least frequently targeted behavior was smoking (2/17, 12% of the studies). Attrition varied greatly across the studies (0%-37%). Risk of bias was high in 65% (11/17) of the studies, with some concerns in the remaining 35% (6/17). Interventions used various BCTs, and the most frequently used were feedback and monitoring (14/17, 82%), goals and planning (10/17, 59%), antecedents (10/17, 59%), and social support (7/17, 41%).

CONCLUSIONS

This review suggests that, although eHealth interventions may have potential, there are still unanswered questions regarding their effectiveness and what drives the mechanism behind these effects. Low methodological quality, high heterogeneity and complexity, the characteristics of the included samples, and often high attrition rates challenge the investigation of the effectiveness and the making of sound inferences about the effect sizes and significance of the results. To address this, new studies and methods are needed. A megastudy design in which different interventions are evaluated in the same population over the same period on the same outcomes may solve some of the challenges.

TRIAL REGISTRATION

PROSPERO CRD42020202777; https://www-crd-york-ac-uk/prospero/display_record.php?RecordID=202777.

Cost-effectiveness of proprotein convertase subtilisin/kexin type 9 inhibition with evolocumab in patients with a history of myocardial infarction in Sweden

Aims

To assess the cost-effectiveness of proprotein convertase subtilisin/kexin type 9 inhibition with evolocumab added to standard-of-care lipid-lowering treatment [maximum tolerated dose (MTD) of statin and ezetimibe] in Swedish patients with a history of myocardial infarction (MI).

Methods and results

Cost-effectiveness was evaluated using a Markov model based on Swedish observational data on cardiovascular event rates and efficacy from the FOURIER trial. Three risk profiles were considered: recent MI in the previous year; history of MI with a risk factor; and history of MI with a second event within 2 years. For each population, three minimum baseline low-density lipoprotein cholesterol (LDL-C) levels were considered: 2.5 mmol/L (≈100 mg/dL), based on the current reimbursement recommendation in Sweden; 1.8 mmol/L (≈70 mg/dL), based on 2016 ESC/EAS guidelines; and 1.4 mmol/L (≈55 mg/dL), or 1.0 mmol/L (≈40 mg/dL) for MI with a second event, based on 2019 ESC/EAS guidelines. Proprotein convertase subtilisin/kexin type 9 inhibition with evolocumab was associated with increased quality-adjusted life-years and costs vs. standard-of-care therapy. Incremental cost-effectiveness ratios (ICERs) were below SEK700 000 (∼€66 500), the generally accepted willingness-to-pay threshold in Sweden, for minimum LDL-C levels of 2.3 (recent MI), 1.7 (MI with a risk factor), and 1.7 mmol/L (MI with a second event). Sensitivity analyses demonstrated that base-case results were robust to changes in model parameters.

Conclusion

Proprotein convertase subtilisin/kexin type 9 inhibition with evolocumab added to MTD of statin and ezetimibe may be considered cost-effective at its list price for minimum LDL-C levels of 1.7–2.3 mmol/L, depending on risk profile, with ICERs below the accepted willingness-to-pay threshold in Sweden.

The Role of Exercise in Reducing Hyperlipidemia-Induced Neuronal Damage in Apolipoprotein E-Deficient Mice

Hyperlipidemia causes nervous system-related diseases. Exercise training has developed into an established evidence-based treatment strategy that is beneficial for neuronal injury. This study investigated the effect of exercise on hyperlipidemia-induced neuronal injury in apolipoprotein E-deficient (ApoE^-/-) mice. Male ApoE^-/- mice (age: 8 weeks) were randomly divided into four groups as follows: mice fed a normal diet (ND), normal diet+swimming training (ND+S), high-fat diet (HD), and high-fat diet+swimming (HD+S). Exercise training consisted of swimming for 40 min/day, 5 days/week for 12 weeks. After 12 weeks, we measured serum levels of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-c). We also evaluated glial fibrillary acidic protein (GFAP) expression levels using immunohistochemistry, real-time PCR, and immunoblotting. In addition, NLR family pyrin domain-containing 3 (NLRP3), interleukin- (IL-) 18, caspase-1, Bax, Bcl-2, and phosphorylated extracellular signal-regulated kinase (p-ERK) expression levels were measured using immunoblotting. Serum levels of TG, TC, and LDL-c were lower in ApoE^-/- HD+S mice than in ApoE^-/- HD mice. Immunohistochemistry, real-time PCR, and immunoblotting showed increased levels of GFAP in the ApoE^-/- HD group. Immunoblotting revealed increased levels of NLRP3, IL-18, caspase-1, Bax, Bcl-2, and p-ERK in the ApoE^-/- HD group; however, they were significantly suppressed in the ApoE^-/- HD+S group. Therefore, exercise has protective effects against neuronal injury caused by hyperlipidemia.

Economic Burden of Stroke Disease: A Systematic Review

Globally, one of the main causes of non-communicable disease as a cause of death every year is stroke. The objective of this study was to analyze the burden in consequence of stroke. This research used a systematic review method. Furthermore, a search for articles was carried out in June–July 2020. Four databases were used to search articles from 2015 to 2020. Eligible studies were identified, analyzed, and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The inclusion criteria were prospective cost studies, retrospective cost studies, database analysis, mathematical models, surveys, and COI studies that assess burden of stroke in primary and referral healthcare (hospital-based). The results showed that from four databases, 9270 articles were obtained, and 13 articles were qualified. A total of 9270 articles had the identified search keywords, but only 13 articles met the set criteria for inclusion. The criteria for inclusion were stroke patients, the economic burden of stroke disease based on cost of illness method, which is approximately equal to USD 1809.51–325,108.84 (direct costs 86.2%, and indirect costs 13.8%). Those that used the health expenditure method did not present the total cost; instead, only either direct or indirect cost of health expenditure were reported. For most hospital admissions due to stroke, LOS (length of stay) was the dominant cost. The high economic burden to manage stroke justifies the promotion and preventive efforts by the policymakers and motivates the practice of healthy lifestyles by the people.

Patients' productivity losses and informal care costs related to ischemic stroke: a French population-based study

BACKGROUND AND PURPOSE

Large societal costs of stroke should not be ignored. We aimed to estimate patients' productivity losses and informal care costs during the first year after ischemic stroke.

METHODS

A cross-sectional survey was performed within the STROKE69 regional population-based cohort study. At 1 year post-stroke, each patient and the corresponding main informal caregiver received questionnaires followed by a telephone interview if necessary. Time losses were valued using the human capital approach and proxy good method for patients with and without a professional activity, respectively.

RESULTS

Among the 222 patients with ischemic stroke (58% men; mean age 68 years; and 86% with a modified Rankin Scale (mRS) score of <3 at 3 months), 54%, 32%, and 25% received informal, formal, and both cares, respectively. Among the 108 main informal caregivers, 63% were women, 74% lived with the patient, and 57% were retired or unemployed. The mean cost of productivity losses was estimated at €7589 ± €12 305 per patient in the first post-stroke year with 5.4%, 71.2%, and 23.4% of these being attributed to presenteeism, absenteeism, and leisure time, respectively. Informal care was given at an average of 25 h/week. The annual mean estimated total cost of informal care was €10 635 per caregiver.

CONCLUSIONS

Informal care and productivity losses of patients with ischemic stroke during the first post-stroke year represent a significant economic burden for society comparable to direct costs. These costs should be included in economic evaluations with the adoption of a societal perspective to avoid underestimating the societal stroke economic burden.

Improvement in serum lipids and liver morphology after supplementation of the diet with fish oil is more evident under regular feeding conditions than under high-fat or mixed diets in rats

BACKGROUND

Dietary n- 3 polyunsaturated fatty acids (PUFAs) have a role in preventing cardiovascular and hepatic diseases. However, their effects might differ significantly depending on individual dietary patterns. The aim of the present study was to evaluate the effects of dietary supplementation with ω-3 fatty acids (FA), administered in different schedules, on hepatic and aortic histological structure, lipid profile, and body weight (BW) in male Wistar rats under standard (SD), high-fat diet (HFD) and mixed feeding conditions.

METHODS

PUFA treatment consisted of the administration of 50 mg/kg fish oil (FO) daily by oral gavage. HFD was obtained by adding a suspension of 4% cholesterol, thiouracil and cholic acid to the animals' drinking water. The rats were maintained on the diets for 6 weeks, and different schedules of PUFA administration were used. At 14, 28, and 42 days, the morphology of liver and aortic samples and the levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), and triglycerides (TG) were assessed.

RESULTS

The HFD groups exhibited significant hyperlipidemia and aortic inflammation, with progression to atherogenesis after 6 weeks. Administration of PUFAs slightly attenuated the aortic changes in these groups and reduced the liver's tendency to steatosis. FO-induced metabolic improvement was more evident in SD than in HFD rats. For instance, after the first 2 weeks, SD animals that received PUFAs had significantly increased HDL levels vs. controls (62.375 ± 4.10 vs. 52.625 ± 8.38 mg/dL, P < 0.05), but HFD rats did not, and decreased TG levels were observed exclusively in the SD rats (57.6 ± 4.09 vs. 66 ± 4.69 mg/dL, P < 0.05). After 6 weeks of n- 3 PUFA administration, LDL was significantly lower in the SD rats than in controls (13.67 ± 4.13 vs. 30.83 ± 2.86 mg/dL, P < 0.001), but the decrease in the HFD rats, although significant (49.17 ± 5.85 mg/dL vs. 57.17 ± 4.96 g/dL, P < 0.05), was not as marked. In the mixed-diet groups, administration of 50 mg/kg/day FO for 14 days under SD conditions following 4 weeks of HFD slightly decreased TG (86.625 ± 11.67 vs. 73 ± 4.52 mg/dL, P < 0.05) and increased HDL (45.875 ± 5.28 vs. 56 ± 3.16 mg/dL). However, in these animals, n-3 PUFA administration had no effect on LDL or TC. Administration of half of the above dose failed to improve any biochemical parameters. FO protected against excessive weight gain mainly under SD conditions.

CONCLUSIONS

The results show that FO confers more protection against cardiovascular risk factors (increased LDL and TG, decreased HDL) and liver lipid accumulation when given to rats consuming regular diets than when given to rats consuming a high-fat diet. This argues that priority should be given to consumption of a healthy diet rather than to the use of supplements. The effectiveness of n-3 PUFAs might be reduced in the case of hyperlipidic intake or after consumption of a high-fat diet.

Epidemiology of benign essential blepharospasm: A nationwide population-based retrospective study in Taiwan

IMPORTANCE

This study provides a nationwide, population-based data on the incidence of benign essential blepharospasm in Asian adults.

BACKGROUND

To describe the incidence, patient demographics, and risk factors associated with benign essential blepharospasm.

DESIGN

Population-based retrospective study.

PARTICIPANTS AND SAMPLES

A total of 1325 patients with benign essential blepharospasm were identified.

METHODS

Patients with diagnosis of blepharopsasm between January 2000 and December 2013 were sampled using the Longitudinal Health Insurance Database 2000. Secondary blepharospasm that may be related to neurological, trauma, and ocular surface disease were excluded.

MAIN OUTCOME MEASURED

Multivariate conditional logistic regression was used to estimate the odds ratios for potential risk factors of benign essential blepharospasm.

RESULTS

The mean annual incidence was 0.10‰ (0.07‰ for males, and 0.12‰ for females). The peak incidence was in the 50 to 59-year-old age group (0.19‰). People living in urban regions have more risk of developing blepharospasm comparing to people living in less urban regions (p <0.01). White-collar workers also have higher chance of having blepharospasm (p<0.001). Significant difference between control group and case group in hyperlipidemia (p <0.001), sleep disorders (p <0.001), mental disorders (depression, anxiety, obsessive compulsive disorder) (p <0.001), dry eye-related diseases (dry eye, Sjögren's syndrome) (p <0.001), Parkinson's disease (p <0.004), and rosacea (p <0.021) were also identified.

CONCLUSIONS AND RELEVANCE

Higher level of urbanization, white-collar work, sleep disorders, mental health diseases, dry eye-related diseases, Parkinsonism, and rosacea are possible risk factors for benign essential blepharospasm.

Trends in diagnosis-specific work disability before and after ischaemic heart disease: a nationwide population-based cohort study in Sweden

OBJECTIVES

We examined trends of diagnosis-specific work disability before and after ischaemic heart disease (IHD).

DESIGN

Participants were followed 4 years before and 4 years after an IHD event for diagnosis-specific work disability (sickness absence and disability pension).

SETTING AND PARTICIPANTS

A Swedish population-based cohort study using register data on all individuals aged 25-60 years, living in Sweden, and who suffered their first IHD event in 2006-2008 (n=23 971) was conducted.

RESULTS

Before the event, the most common diagnoses of work disability were musculoskeletal disorders (21 annual days for men and 44 for women) and mental disorders (19 men and 31 for women). After multivariable adjustments, we observed a fivefold increase (from 12 to 60 days) in work disability due to diseases of the circulatory system in the first postevent year compared with the last pre-event year among men. Among women, the corresponding increase was fourfold (from 14 to 62 days). By the second postevent year, the number of work disability days decreased significantly compared with the first postevent year among both sexes (to 19 days among men and 23 days among women). Among women, mean days of work disability due to diseases of the circulatory system remained at a higher level than among men during the postevent years. Work disability risk after versus before an IHD event was slightly higher among men (rate ratio (RR) 2.49; 95% CI 2.36 to 2.62) than among women (RR 2.29, 95% CI 2.12 to 2.49). When pre-event long-term work disability was excluded, diseases of the circulatory system were the most prevalent diagnosis for work disability after an IHD event among both men and women.

CONCLUSIONS

An IHD event was strongly associated with an increase in work disability due to diseases of the circulatory system, especially among men and particularly in the first postevent year.

Hospital and Institutionalisation Care Costs after Limb and Visceral Ischaemia Benchmarked Against Stroke: Long-Term Results of a Population Based Cohort Study

OBJECTIVE/BACKGROUND

There are few published data on the acute care or long-term costs after acute/critical limb or visceral ischaemia (ACLVI) events. Using data from patients with acute events in a population based incidence study (Oxford Vascular Study), the present study aimed to determine the long-term costs after an ACLVI event.

METHODS

All patients with first ever incident ACLVI from 2002 to 2012 were included. Analysis was based on follow up until January 2017, with all patients having full 5 year follow up. Multivariate regressions were used to assess baseline and subsequent predictors of total 5 year hospital care costs. Overall costs after an ACLVI event were benchmarked against those after stroke in the same population, during the same period.

RESULTS

Among 351 patients with an ACLVI event, mean 5 year total care costs were €35,211 (SD 50,500), of which €6443 (18%) were due to long-term institutionalisation. Costs differed by type of event (acute visceral ischaemia €16,476; acute limb ischaemia €24,437; critical limb ischaemia €46,281; p < 0.001). Results of the multivariate analyses showed that patients with diabetes and those undergoing above knee amputations incurred additional costs of €11,804 (p = 0.014) and €25,692 (p < 0.001), respectively. Five year hospital care costs after an ACLVI event were significantly higher than after stroke (€28,768 vs. €22,623; p = 0.004), but similar after including long-term costs of institutionalisation (€35,211 vs. €35,391; p = 0.957).

CONCLUSION

Long-term care costs after an ACLVI event are considerable, especially after critical limb ischaemia. Hospital care costs were significantly higher than for stroke over the long term, and were similar after inclusion of costs of institutionalisation.

Work disability in gout: a population-based case–control study

Objectives

To examine the extent and cost of work disability among patients with gout compared with matched population controls and to analyse predictors of work disability.

Methods

A regional cohort study using data from Swedish national and regional registries from January 2000 through December 2012, including 4571 patients with gout of working age, with a first recorded diagnosis of gout in the years 2003–2009 and 22 482 population controls, matched by age, sex and place of residence. Differences in baseline characteristics (educational level, income, previous employment and comorbidities) and the number of work-loss days (absenteeism) due to sick leave and disability pension for 3 years after identification were calculated. Predictors for new-onset work absenteeism (>90 days/year) in a subset were determined by conditional logistic regression.

Results

Patients with gout (median age 53 years) had significantly more comorbidities, lower income and lower level of education than matched controls. The average work absentee rate during the 3-year follow-up period was higher among patients with gout than controls, 22% and 14%, respectively (P<0.0001). New-onset absenteeism was in multivariate analyses significantly predicted by gout (OR 1.47; 95% CI 1.23 to 1.75). Other variables independently related to new-onset absenteeism were education ≤12 years, previous unemployment and history of sick leave, in addition to several comorbidities (renal disease, cardiovascular disease, alcohol abuse and obesity).

Conclusions

Gout is associated with substantially higher work absenteeism and costs for society due to productivity loss, after adjusting for associated comorbidities and socioeconomic differences. Whether more intensive treatment of gout is cost-effective needs to be addressed in future studies.

Work disability before and after a major cardiovascular event: a ten-year study using nationwide medical and insurance registers

We examined the trajectories of work disability before and after IHD and stroke events. New IHD (n = 13521) and stroke (n = 7162) cases in 2006–2008 were retrieved from nationwide Swedish hospital records and their annual work disability days five years before and after the date of diagnosis were retrieved from a nationwide disability register. There was no pre-event differences in disability days between the IHD and stroke cases and five years prior to the event, they were close to those observed in the general population. In the first post-event year, the adjusted mean days increased to 83.9 (95% CI 80.6–86.5) in IHD; to 179.5 (95% CI 172.4–186.8) in stroke, a six-fold increase in IHD and 14-fold in stroke. Work disability leveled off among the IHD cases but not among those who had stroke. The highest disability levels for the fifth post-event year after a stroke event was associated with pre-existing diabetes (146.9), mental disorder (141.2), non-employment (137.0), and immigrant status (117.9). In a working-age population, the increase in work disability after a cardiovascular event decreases close to the pre-event level in IHD but remains particularly high after stroke; among patients with comorbid depression or diabetes, immigrants, and those not in employment.

Effects of the duration of hyperlipidemia on cerebral lipids, vessels and neurons in rats

Background

The present study was designed to investigate the effects of hyperlipidemia on the cerebral lipids, vessels and neurons of rats, and to provide experimental evidence for subsequent intervention.

Method

One hundred adult SD rats, half of which were male and half of which were female, were randomly divided into five groups on the basis of serum total cholesterol (TC) levels. Four groups were fed a hypercholesterolemic diet (rat chow supplemented with 4% cholesterol, 1% cholic acid and 0.5% thiouracil – this is also called a CCT diet) for periods of 1 week, 2 weeks, 3 weeks and 4 weeks, respectively. A control group was included. The levels of serum lipids, cerebral lipids, free fatty acids (FFA), interleukin-6 (IL-6), interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-α), vascular endothelial growth factor (VEGF), oxidized low density lipoprotein (ox-LDL), A-beta precursor proteins (APP), amyloid beta (Aβ), glial fibrillary acidic protein (GFAP) and tight junction protein Claudin-5 were measured after the experiment. The pathologic changes and apoptosis of the rat brains were evaluated.

Results

Compared with the control group, after 1 week of a CCT diet, the levels of serum total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C) and brain triglycerides had increased by 2.40, 1.29 and 1.75 and 0.3 times, respectively. The serum high density lipoprotein cholesterol (HDL-C) had decreased by 0.74 times (P < 0.05) and the expression of IL-1, TNF-α and GFAP in the brains had increased (P < 0.05). In the second week, the expression of FFA and APP in the brains, and the amount of apoptotic neurons, had increased (P < 0.05). In the third week, the levels of VEGF, Ox-LDL and Aβ had increased, and the expression of Claudin-5 had decreased in the brains (P < 0.05). In the fourth week, the levels of TC, LDL-C and the amount of apoptotic neurons had increased (P < 0.05). The correlation analysis showed a positive correlation among FFA, TNF-α, VEGF, ox-LDL, Aβ, GFAP and neuronal apoptosis in the rat brains, and they all were negatively correlated with Claudin-5 (P < 0.05).

Conclusion

Hyperlipidemia may activate astrocytes by means of high levels of TG that will have direct toxic effects on the cerebral vessels and neurons by causing the secretion of TNF-α and IL-1 in the brains of rats. In the metabolic procession, brain tissue was shown to generate FFA that aggravated the biosynthesis of ox-LDL. With the extension of the duration of hyperlipidemia, high levels of cerebral TC and LDL-C were shown to aggravate the deposition of Aβ, induce the secretion of VEGF, reduce the expression of tight junction protein Claudin-5 and change the permeability of blood–brain barriers to factors that could damage cerebral vessels and neurons.