The general aim of this thesis was to study the frequency, causes and consequences of pathologic brain aging specifically focusing on sub-clinical and clinical MRI manifestations of vascular (small... Show moreThe general aim of this thesis was to study the frequency, causes and consequences of pathologic brain aging specifically focusing on sub-clinical and clinical MRI manifestations of vascular (small vessel disease) and neurodegenerative (brain atrophy) disease. A second aim was to improve the accuracy of the tools to quantify brain tissue so to better reflect the imaging characteristics of older people. All data presented in this thesis are from the AGES-Reykjavik Study including 5764 elderly men and women. The data is based on cross-sectional and longitudinal assessments of the brain with MRI measures. Show less
Worldwide, life expectancy has increased, which also resulted in an increasing number of people reaching old age. With aging, several age-related diseases commonly occur, such as dementia,... Show moreWorldwide, life expectancy has increased, which also resulted in an increasing number of people reaching old age. With aging, several age-related diseases commonly occur, such as dementia, osteoporosis and cardiovascular disease. The occurence of these diseases with age is highly heterogeneous. The research described in this thesis assessed the role of thyroid hormones in the etiology of age-related diseases. Based on the results, variation in blood levels of thyroid hormones do not appear to play a major role in the development of cogniitve decline, osteoporosis, anemia, diabetes mellitus or cardiovascular disease. Therefore, we conclude that is unlikely that thyroid hormones are a modifiable risk factor in the aging process. Nevertheless, many other research questions remain regarding thyroid hormones and older individuals. Show less
Zwartbol, M.H.T.; Ghaznawi, R.; Jaarsma-Coes, M.; Kuijf, H.; Hendrikse, J.; Bresser, J. de; ... ; UCC-SMART Study Grp 2022
White matter hyperintensity (WMH) shape has been associated with the severity of the underlying brain pathology, suggesting it is a potential neuroimaging marker of WMH impact on brain function.In... Show moreWhite matter hyperintensity (WMH) shape has been associated with the severity of the underlying brain pathology, suggesting it is a potential neuroimaging marker of WMH impact on brain function.In 563 patients with vascular disease (58 +/- 10 years), we examined the relationship between WMH volume, shape, and cognitive functioning. WMH volume and shape were automatically determined on 1.5T brain MRI data. Standardized linear regression analyses estimated the association between WMH volume and shape (concavity index, solidity, convexity, fractal dimension, and eccentricity) and memory and executive functioning, adjusted for age, sex, educational level, and reading ability.Larger WMH volumes were associated with lower executive functioning Z-scores ( b (95%-CI):-0.09 (-0.17;-0.01)). Increased shape complexity of periventricular/confluent WMH associated with lower exec-utive functioning (concavity index + 1SD:-0.13 (-0.20;-0.06); solidity-1SD:-0.09 (-0.17;-0.02)) and lower memory function (fractal dimension + 1SD:-0.10 (-0.18;-0.02)). Of note, the association between concav-ity index and executive functioning was independent of WMH volume (-0.12 (-0.19;-0.04)). Our results suggest that WMH shape contains additional information about WMH burden, not other-wise captured by WMH volume.(c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ ) Show less
Giacconi, R.; D'Aquila, P.; Malavolta, M.; Piacenza, F.; Burkle, A.; Villanueva, M.M.; ... ; Provinciali, M. 2022
Aging and age-related diseases have been linked to microbial dysbiosis with changes in blood bacterial DNA concentration. This condition may promote chronic low-grade inflammation, which can be... Show moreAging and age-related diseases have been linked to microbial dysbiosis with changes in blood bacterial DNA concentration. This condition may promote chronic low-grade inflammation, which can be further aggravated by antioxidant nutrient deficiency. Low plasma carotenoids are associated with an increased risk of inflammation and cellular damage and predict mortality. However, no evidence is yet available on the relationship between antioxidants and the blood bacterial DNA (BB-DNA). Therefore, this study aimed to compare BB-DNA from (a) GO (nonagenarian offspring), (b) age-matched controls (Randomly recruited Age-Stratified Individuals from the General population [RASIG]), and (c) spouses of GO (SGO) recruited in the MARK-AGE project, as well as to investigate the association between BB-DNA, behavior habits, Charlson Comorbidity Index (CCI), leucocyte subsets, and the circulating levels of some antioxidants and oxidative stress markers. BB-DNA was higher in RASIG than GO and SGO, whereas GO and SGO participants showed similar values. BB-DNA increased in smokers and males with CCI >= 2 compared with those with CCI <= 1 within RASIG. Moreover, BB-DNA was positively associated with lymphocyte, neutrophil, and monocyte counts, but not with self-reported dietary habits. Higher quartiles of BB-DNA were associated with low lutein and zeaxanthin and elevated malondialdehyde plasma concentrations in RASIG. BB-DNA was also positively correlated with nitric oxide levels. Herein, we provide evidence of a reduced BB-DNA in individuals from long-living families and their spouses, suggesting a decreased microbial dysbiosis and bacterial systemic translocation. BB-DNA was also associated with smoking, CCI, leukocyte subsets, and some redox biomarkers in older participants. Show less
The experimental research in this thesis aims to gain more understanding of how the SCN network is organized and what is needed for network changes. More specifically, this work focused on the... Show moreThe experimental research in this thesis aims to gain more understanding of how the SCN network is organized and what is needed for network changes. More specifically, this work focused on the potential role of GABA and the GABAeric E/I balance in SCN network plasticity. Communication and synchronization in the SCN are important for the generation of a strong and coherent output signal. Under certain conditions, like long photoperiod, the phases of the individual SCN cells are more dispersed over the 24 hour cycle as evidenced by measurements of electrical activity and clock gene expression. Aging is also known to affect the network organization of the SCN with deterioration in synchronization among the individual SCN neurons. In this thesis, I present work that contributes to research questions regarding the effect of light exposure and/or aging on several characteristics of SCN network plasticity. Show less
The 14q32 locus is an imprinted region in the human genome which contains multiple non-coding RNAs. We investigated the role of the long non-coding RNA maternally expressed gene 8 (MEG8) in... Show moreThe 14q32 locus is an imprinted region in the human genome which contains multiple non-coding RNAs. We investigated the role of the long non-coding RNA maternally expressed gene 8 (MEG8) in endothelial function and its underlying mechanism. A 5-fold increase in MEG8 was observed with increased passage number in human umbilical vein endothelial cells (HUVECs), suggesting MEG8 is induced during aging. MEG8 knockdown resulted in a 1.8-fold increase in senescence, suggesting MEG8 might be protective during aging. The endothelial barrier was also impaired after MEG8 silencing. MEG8 knockdown resulted in reduced expression of microRNA (miRNA)-370 and -494 but not -127, -487b and -410. Overexpression of miRNA-370 or -494 partially rescued the MEG8-silencing-induced barrier loss. Mechanistically, MEG8 regulates expression of miRNA-370 and -494 at the mature miRNA level through interaction with the RNA-binding proteins cold-inducible RNA-binding protein (CIRBP) and hydroxyacyl-CoA dehydrogenase trifunctional multi-enzyme complex subunit beta (HADHB). Mature miRNA-370 and miRNA-494 were found to interact with CIRBP, whereas precursor miRNA-370 and miRNA-494 were found to interact with HADHB. Individual CIRBP and HADHB silencing resulted in downregulation of miRNA-370 and induction of miRNA-494. These results suggest MEG8 interacts with CIRBP and HADHB and contributes to miRNA processing at the post-transcriptional level. Show less
Hitzl, W.; Stamm, T.; Kloppenburg, M.; Ritter, M.; Gaisberger, M.; Zee-neuen, A. van der 2022
Background The present study aimed to predict the expected number of patients with osteoarthritis (OA) in Austria up to the year 2080. Methods Demographic data and population projections between... Show moreBackground The present study aimed to predict the expected number of patients with osteoarthritis (OA) in Austria up to the year 2080. Methods Demographic data and population projections between 2019 and 2080 were obtained from European authorities. Information about recent age- and sex-stratified prevalence of patients with self-reported physician-diagnosed OA was obtained from the Austrian Health Interview Survey (n = 15,771). Projections were stratified by age and sex; sensitivity analyses were performed based on aging, main (most likely), and growth scenarios of the population. Results Based on the projection, the overall increase in the total number of patients with OA from 2019 to 2080 will be 38% for men and women. In 2019, the highest number of OA-patients nested in the groups of persons aged 70-79 (n = 238,749) and 60-69 (n = 237,729) years. In 2080, the 80+ age group is predicted to have the highest number of OA with 421,548 individuals (i.e. factor 3.45 and factor 2.48 increase in the male and female group, respectively, compared to 2019), followed by the group aged 70-79 with 314,617 individuals (factor 1.45 and factor 1.28 increase in the male and female group, respectively, compared to 2019). Similar trends were found in the ageing and growing scenarios. Conclusions The projected increase in the occurrence of OA will likely lead to a substantial socioeconomic burden for the Austrian healthcare system in the near and far future. The current findings plead for the development of sustainable concepts for the treatment and prevention of OA by European authorities. Show less
The significance of classical risk factors in coronary artery disease (CAD) remains unclear in older age due to possible changes in underlying disease pathologies. Therefore, we conducted Mendelian... Show moreThe significance of classical risk factors in coronary artery disease (CAD) remains unclear in older age due to possible changes in underlying disease pathologies. Therefore, we conducted Mendelian Randomization approaches to investigate the causal relationship between classical risk factors and primary CAD in different age groups. A Mendelian Randomization study was conducted in European-ethnicity individuals from the UK Biobank population. Analyses were performed using data of 22,313 CAD cases (71.6% men) and 407,920 controls (44.5% men). Using logistic regression analyses, we investigated the associations between standardized genetic risk score and primary CAD stratified by age of diagnosis. In addition, feature importance and model accuracy were assessed in different age groups to evaluate predictive power of the genetic risk scores with increasing age. We found age-dependent associations for all classical CAD risk factors. Notably, body mass index (OR 1.22 diagnosis < 50 years; OR 1.02 diagnosis > 70 years), blood pressure (OR 1.12 < 50 years; OR 1.04 > 70 years), LDL cholesterol (OR 1.16 < 50 years; OR 1.02 > 70 years), and triglyceride levels (OR 1.11 < 50 years; 1.04 > 70 years). In line with the Mendelian Randomization analyses, model accuracy and feature importance of the classical risk factors decreased with increasing age of diagnosis. Causal determinants for primary CAD are age dependent with classical CAD risk factors attenuating in relation with primary CAD with increasing age. These results question the need for (some) currently applied cardiovascular disease risk reducing interventions at older age. Show less
Candel, B.G.J.; Ingen, I.B. van; Doormalen, I.P.H. van; Raven, W.; Mignot-Evers, L.A.A.; Jonge, E. de; Groot, B. de 2021
Purpose To assess how often baseline systolic blood pressure (SBP) could be retrieved from the Electronic Health Record (EHR) in older Emergency Department (ED) patients. Second, to assess whether... Show morePurpose To assess how often baseline systolic blood pressure (SBP) could be retrieved from the Electronic Health Record (EHR) in older Emergency Department (ED) patients. Second, to assess whether the difference between baseline SBP and initial SBP in the ED (Delta SBP) was associated with 30-day mortality. Methods A multicenter hypothesis-generating cohort study including patients >= 70 years. EHRs were searched for baseline SBPs. The association between Delta SBP and 30-day mortality was investigated. Results Baseline SBP was found in 220 out of 300 patients (73.3%; 95%CI 68.1-78.0%). In 72 patients with normal initial SBPs (133-166 mmHg) in the ED, fifteen (20.8%) had a negative Delta SBP with 20.0% mortality. A negative Delta SBP was associated with 30-day mortality (AHR 4.7; 1.7-12.7). Conclusion Baseline SBPs are often available in older ED patients. The Delta SBP has prognostic value and could be used as an extra variable to recognize hypotension in older ED patients. Future studies should clarify whether the Delta SBP improves risk stratification in the ED.Key summary pointsAim To investigate whether a baseline systolic blood pressure (SBP) in older Emergency Department (ED) patients of >= 70 years has prognostic value, when compared with the initial SBP at presentation in the ED (= Delta SBP). Findings A baseline SBP could be retrieved from the Electronic Health Record for most older ED patients (73.3%). A negative Delta SBP was associated with 30-day mortality. In 20% of the patients with a normal initial SBP in the ED, the Delta SBP was negative, with a high mortality rate. Message A baseline SBP value could be retrieved from the Electronic Health Record in most hospitalized ED patients >= 70 years. In addition, the 21% with a normal SBP at ED presentation had a negative Delta SBP and these patients had an increased risk for 30-day mortality. As a result, Delta SBP may contribute to improved risk stratification and may help to recognize hypotension in older patients. Show less
Panagiotou, M.; Michel, S.; Meijer, J.H.; Deboer, T. 2021
Aging is a multifactorial process likely stemming from damage accumulation and/or a decline in maintenance and repair mechanisms in the organisms that eventually determine their lifespan. In our... Show moreAging is a multifactorial process likely stemming from damage accumulation and/or a decline in maintenance and repair mechanisms in the organisms that eventually determine their lifespan. In our review, we focus on the morphological and functional alterations that the aging brain undergoes affecting sleep and the circadian clock in both human and rodent models. Although both species share mammalian features, differences have been identified on several experimental levels, which we outline in this review. Additionally, we delineate some challenges on the preferred analysis and we suggest that a uniform route is followed so that findings can be smoothly compared. We conclude by discussing potential interventions and highlight the influence of physical exercise as a beneficial lifestyle intervention, and its effect on healthy aging and longevity. We emphasize that even moderate age-matched exercise is able to ameliorate several aging characteristics as far as sleep and circadian rhythms are concerned, independent of the species studied. Show less
VERHEGGEN, I.C.M., W. Freeze, J. de Jong, J. Jansen, A. Postma, M. van Boxtel, F. Verhey and W. Backes. The application of contrast-enhanced MRI in the assessment of blood-cerebrospinal fluid... Show moreVERHEGGEN, I.C.M., W. Freeze, J. de Jong, J. Jansen, A. Postma, M. van Boxtel, F. Verhey and W. Backes. The application of contrast-enhanced MRI in the assessment of blood-cerebrospinal fluid barrier integrity. Choroid plexus epithelial cells form a barrier that enables active, bidirectional exchange between the blood plasma and cerebrospinal fluid (CSF), known as the blood-CSF barrier (BCSFB). Through its involvement in CSF composition, the BCSFB maintains homeostasis in the central nervous system. While the relation between bloodbrain barrier disruption, aging and neurodegeneration is extensively studied using contrast-enhanced MRI, applying this technique to investigate BCSFB disruption in age-related neurodegeneration has received little attention. This review provides an overview of the current status of contrast-enhanced MRI to assess BCSFB permeability. Post-contrast ventricular gadolinium enhancement has been used to indicate BCSFB permeability. Moreover, new techniques highly sensitive to low gadolinium concentrations in the CSF, for instance heavily T2weighted imaging with cerebrospinal fluid suppression, seem promising. Also, attempts are made at using other contrast agents, such as manganese ions or very small superparamagnetic iron oxide particles, that seem to be cleared from the brain at the choroid plexus. Advancing and applying new developments such as these could progress the assessment of BCSFB integrity. Show less
Kim, M.; Lee, S.P.; Kwak, S.; Yang, S.; Kim, Y.J.; Andreini, D.; ... ; Chang, H.J. 2021
Background: The association of age with coronary plaque dynamics is not well characterized by coronary computed tomography angiography (CCTA).Methods: From a multinational registry of patients who... Show moreBackground: The association of age with coronary plaque dynamics is not well characterized by coronary computed tomography angiography (CCTA).Methods: From a multinational registry of patients who underwent serial CCTA, 1153 subjects (61 +/- 5 years old, 61.1% male) were analyzed. Annualized volume changes of total, fibrous, fibrofatty, necrotic core, and dense calcification plaque components of the whole heart were compared by age quartile groups. Clinical events, a composite of all-cause death, acute coronary syndrome, and any revascularization after 30 days of the initial CCTA, were also analyzed. Random forest analysis was used to define the relative importance of age on plaque progression.Results: With a 3.3-years' median interval between the two CCTA, the median annual volume changes of total plaque in each age quartile group was 7.8, 10.5, 10.8, and 12.1 mm(3)/year and for dense calcification, 2.5, 4.6, 5.4, and 7.1 mm(3)/year, both of which demonstrated a tendency to increase by age (p-for-trend = 0.001 and < 0.001, respectively). However, this tendency was not observed in any other plaque components. The annual volume changes of total plaque and dense calcification were also significantly different in the propensity score-matched lowest age quartile group versus the other age groups as was the composite clinical event (log-rank p = 0.003). In random forest analysis, age had comparable importance in the total plaque volume progression as other traditional factors.Conclusions: The rate of whole-heart plaque progression and dense calcification increases depending on age. Age is a significant factor in plaque growth, the importance of which is comparable to other traditional risk factors. Show less
Background Aging is a multifactorial process that affects multiple tissues and is characterized by changes in homeostasis over time, leading to increased morbidity. Whole blood gene expression... Show moreBackground Aging is a multifactorial process that affects multiple tissues and is characterized by changes in homeostasis over time, leading to increased morbidity. Whole blood gene expression signatures have been associated with aging and have been used to gain information on its biological mechanisms, which are still not fully understood. However, blood is composed of many cell types whose proportions in blood vary with age. As a result, previously observed associations between gene expression levels and aging might be driven by cell type composition rather than intracellular aging mechanisms. To overcome this, previous aging studies already accounted for major cell types, but the possibility that the reported associations are false positives driven by less prevalent cell subtypes remains. Results Here, we compared the regression model from our previous work to an extended model that corrects for 33 additional white blood cell subtypes. Both models were applied to whole blood gene expression data from 3165 individuals belonging to the general population (age range of 18-81 years). We evaluated that the new model is a better fit for the data and it identified fewer genes associated with aging (625, compared to the 2808 of the initial model; P <= 2.5x10(-6)). Moreover, 511 genes (similar to 18% of the 2808 genes identified by the initial model) were found using both models, indicating that the other previously reported genes could be proxies for less abundant cell types. In particular, functional enrichment of the genes identified by the new model highlighted pathways and GO terms specifically associated with platelet activity. Conclusions We conclude that gene expression analyses in blood strongly benefit from correction for both common and rare blood cell types, and recommend using blood-cell count estimates as standard covariates when studying whole blood gene expression. Show less
Jung, Y.J.; Viviano, R.P.; Rooden, S. van; Grond, J. van der; Rombouts, S.A.R.B.; Damoiseaux, J.S. 2021
Background: White matter hyperintensities (WMH) show a robust relationship with arterial pressure as well as objective and subjective cognitive functioning. In addition, APOE epsilon 4 carriership... Show moreBackground: White matter hyperintensities (WMH) show a robust relationship with arterial pressure as well as objective and subjective cognitive functioning. In addition, APOE epsilon 4 carriership may influence how arterial pressure affects cognitive functioning.Objective: To determine the role of region-specific WMH burden and APOE epsilon 4 carriership on the relationship between mean arterial pressure (MAP) and cognitive function as well as subjective cognitive decline (SCD).Methods: The sample consisted of 87 cognitively unimpaired middle-aged to older adults aged 50-85. We measured WMH volume for the whole brain, anterior thalamic radiation (ATR), forceps minor, and superior longitudinal fasciculus (SLF). We examined whether WMH burden mediated the relationship between MAP and cognition (i.e., TMT-A score for processing speed; Stroop performance for executive function) as well as SCD (i.e., Frequency of Forgetting (FoF)), and whether APOE epsilon 4 carriership moderated that mediation.Results: WMH burden within SLF mediated the effect of MAP on Stroop performance. Both whole brain and ATR WMH burden mediated the effect of MAP on FoF score. In the MAP-WMH-Stroop relationship, the mediation effect of SLFWMH and the effect of MAP on SLF WMH were significant only in APOE epsilon 4 carriers. In the MAP-WMH-FoF relationship, the effect of MAP on whole brain WMH burden was significant only in epsilon 4 carriers.Conclusion: WMH burden and APOE genotype explain the link between blood pressure and cognitive function and may enable a more accurate assessment of the effect of high blood pressure on cognitive decline and risk for dementia. Show less
Giacconi, R.; Maggi, F.; Macera, L.; Spezia, P.G.; Pistello, M.; Provinciali, M.; ... ; Malavolta, M. 2020
Torquetenovirus (TTV) viremia has been associated with increased mortality risk in the elderly population. This work aims to investigate TTV viremia as a potential biomarker of immunosenescence. We... Show moreTorquetenovirus (TTV) viremia has been associated with increased mortality risk in the elderly population. This work aims to investigate TTV viremia as a potential biomarker of immunosenescence. We compared levels of circulating TTV in 1813 participants of the MARK-AGE project, including human models of delayed (offspring of centenarians [GO]) and premature (Down syndrome [DS]) immunosenescence. The TTV load was positively associated with age, cytomegalovirus (CMV) antibody levels, and the Cu/Zn ratio and negatively associated with platelets, total cholesterol, and total IgM. TTV viremia was highest in DS and lowest in GO, with intermediate levels in the SGO (spouses of GO) and RASIG (Randomly Recruited Age-Stratified Individuals From The General Population) populations. In the RASIG population, TTV DNA loads showed a slight negative association with CD3+T-cells and CD4+T-cells. Finally, males with >= 4log TTV copies/mL had a higher risk of having a CD4/CD8 ratio<1 than those with lower viremia (odds ratio [OR] = 2.85, 95% confidence interval [CI]: 1.06-7.62), as well as reduced CD3+ and CD4+T-cells compared to males with lower replication rates (<4log), even after adjusting for CMV infection. In summary, differences in immune system preservation are reflected in the models of delayed and premature immunosenescence, displaying the best and worst control over TTV replication, respectively. In the general population, TTV loads were negatively associated with CD4+ cell counts, with an increased predisposition for an inverted CD4/CD8 ratio for individuals with TTV loads >= 4log copies/mL, thus promoting an immune risk phenotype. Show less
My research projects include the investigation of effects of different environmental factors on sleep and the circadian clock in the course of aging (such as light levels, exercise, diet and... Show moreMy research projects include the investigation of effects of different environmental factors on sleep and the circadian clock in the course of aging (such as light levels, exercise, diet and pharmacological substances including caffeine and diazepam). Investigating thebeneficial or adverse effects in the course of aging provides significant insights that could accelerate, hinder or ameliorate parts of the aging process allowing for a healthier and longer life span.Chronic consupmtion of high-caloric diet, eventually leading to obesity, alters the sleep homeostasis as well as the sleep architecture denoting a potentially enhanced aging phenotype.In addition to dietary preferences, light levels particularly at night significantly affect sleep and the sleep electroencephalogram across a wide age span, impactingthe sleep regulatory system as well as the brain integrity.Factors that induce beneficial effects include exercise and caffeine intake. Long-term exercise was able to lead to a younger brain phenotype across all ages while caffeine generally ameliorated sleep health. Show less
Montfort, S.J.T. van; Slooter, A.J.C.; Kant, I.M.J.; Leur, R.R. van der; Spies, C.; Bresser, J. de; ... ; Dellen, E. van 2020
Delirium, the clinical expression of acute encephalopathy, is a common neuropsychiatric syndrome that is related to poor outcomes, such as long-term cognitive impairment. Disturbances of functional... Show moreDelirium, the clinical expression of acute encephalopathy, is a common neuropsychiatric syndrome that is related to poor outcomes, such as long-term cognitive impairment. Disturbances of functional brain networks are hypothesized to predispose for delirium. The aim of this study in non-delirious elderly individuals was to investigate whether predisposing risk factors for delirium are associated with fMRI network characteristics that have been observed during delirium. As predisposing risk factors, we studied age, alcohol misuse, cognitive impairment, depression, functional impairment, history of transient ischemic attack or stroke, and physical status. In this multicenter study, we included 554 subjects and analyzed resting-state fMRI data from 222 elderly subjects (63% male, age range: 65-85 year) after rigorous motion correction. Functional network characteristics were analyzed and based on the minimum spanning tree (MST). Global functional connectivity strength, network efficiency (MST diameter) and network integration (MST leaf fraction) were analyzed, as these measures were altered during delirium in previous studies. Linear regression analyses were used to investigate the relation between predisposing delirium risk factors and delirium-related fMRI characteristics, adjusted for confounding and multiple testing. Predisposing risk factors for delirium were not associated with delirium-related fMRI network characteristics. Older age within our elderly cohort was related to global functional connectivity strength (beta = 0.182, p < 0.05), but in the opposite direction than hypothesized. Delirium-related functional network impairments can therefore not be considered as the common mechanism for predisposition for delirium. Show less
Overbeek, C.L.; Kolk, A.; Groot, J.H. de; Witte, P.B. de; Gademan, M.G.J.; Nelissen, R.G.H.H.; Nagels, J. 2019
Middle-aged individuals cocontract with adductor muscles during abduction. This may be crucial for counteracting deltoid forces, depressing the humerus and ensuring free passage of subacromial... Show moreMiddle-aged individuals cocontract with adductor muscles during abduction. This may be crucial for counteracting deltoid forces, depressing the humerus and ensuring free passage of subacromial tissues underneath the acromion during abduction. We questioned whether adductor co-contraction is always present, or develops during ageing, in which case it may explain the age-related character of common shoulder conditions such as Subacromial Pain Syndrome. In a cross-sectional analysis with electromyography (EMG), activation patterns of the latissimus dorsi, teres major, pectoralis major and deltoid muscle were assessed during isometric force tasks in 60 asymptomatic individuals between 21 and 60 years old. Cocontraction was expressed as the degree of antagonistic activation relative to the same muscle's degree of agonistic activation, resulting in an activation ratio between -1 and 1, where lower values indicate more cocontraction. Using linear regression analyses, we found age-related decreases in the activation ratio of the latissimus dorsi (regression estimate: -0.004, 95% CI: -0.007 to 0.0, p-value: 0.042) and teres major (regression estimate: -0.013, 95% CI: -0.019 to -0.008, p-value: < 0.001). In contrast to young individuals, middle-aged individuals showed a high degree of adductor cocontraction during abduction. This may indicate that during ageing, alterations in activation patterns are required for preserving pain-free shoulder function. Show less
Schipper, L.J. de; Hafkemeijer, A.; Bouts, M.J.R.J.; Grond, J. van der; Marinus, J.; Henselmans, J.M.L.; Hilten, J.J. van 2019
