5 results
Brain aging in major depressive disorder
- L. Han, H. Schnack, R. Brouwer, D. Veltman, N. Van Der Wee, M.-J. Van Tol, M. Aghajani, B. Penninx
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- Journal:
- European Psychiatry / Volume 64 / Issue S1 / April 2021
- Published online by Cambridge University Press:
- 13 August 2021, p. S63
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- Article
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Depression and anxiety are common and often comorbid mental health disorders that represent risk factors for aging-related conditions. Brain aging has shown to be more advanced in patients with Major Depressive Disorder (MDD). Here, we extend prior work by investigating multivariate brain aging in patients with MDD and/or anxiety disorders and examine which factors contribute to older appearing brains. Adults aged 18-57 years from the Netherlands Study of Depression and Anxiety underwent structural MRI. A pre-trained brain age prediction model based on >2,000 samples from the ENIGMA consortium was applied to obtain brain-predicted age differences (brain-PAD, predicted brain age minus chronological age) in 65 controls and 220 patients with current MDD and/or anxiety. Brain-PAD estimates were associated with clinical, somatic, lifestyle, and biological factors. After correcting for antidepressant use, brain-PAD was significantly higher in MDD (+2.78 years, Cohen’s d=0.25, 95% CI -0.10-0.60) and anxiety patients (+2.91 years, Cohen’s d=0.27, 95% CI -0.08-0.61), compared to controls. There were no significant associations with lifestyle or biological stress systems. A multivariable model indicated unique contributions of higher severity of somatic depression symptoms (b=4.21 years per unit increase on average sum score) and antidepressant use (-2.53 years) to brain-PAD. Advanced brain aging in patients with MDD and anxiety was most strongly associated with somatic depressive symptomatology. We also present clinically relevant evidence for a potential neuroprotective antidepressant effect on the brain-PAD metric that requires follow-up in future research.
DisclosureNo significant relationships.
Localised estimation and control of linear instabilities in two-dimensional wall-bounded shear flows
- H. J. Tol, M. Kotsonis, C. C. de Visser, B. Bamieh
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- Journal:
- Journal of Fluid Mechanics / Volume 824 / 10 August 2017
- Published online by Cambridge University Press:
- 13 July 2017, pp. 818-865
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A new framework is presented for estimation and control of instabilities in wall-bounded shear flows described by the linearised Navier–Stokes equations. The control design considers the use of localised actuators/sensors to account for convective instabilities in an ${\mathcal{H}}_{2}$ optimal control framework. External sources of disturbances are assumed to enter the control domain through the inflow. A new inflow disturbance model is proposed for external excitation of the perturbation modes that contribute to transition. This model allows efficient estimation of the flow perturbations within the localised control region of a conceptually unbounded domain. The state-space discretisation of the infinite-dimensional system is explicitly obtained, which allows application of linear control theoretic tools. A reduced-order model is subsequently derived using exact balanced truncation that captures the input/output behaviour and the dominant perturbation dynamics. This model is used to design an ${\mathcal{H}}_{2}$ optimal controller to suppress the instability growth. The two-dimensional non-periodic channel flow is considered as an application case. Disturbances are generated upstream of the control domain and the resulting flow perturbations are estimated/controlled using point wall shear measurements and localised unsteady blowing and suction at the wall. The controller is able to cancel the perturbations and is robust to both unmodelled disturbances and sensor inaccuracies. For single-frequency and multiple-frequency disturbances with low sensor noise a nearly full cancellation is achieved. For stochastic forced disturbances and high sensor noise an energy reduction in perturbation wall shear stress of 96 % is shown.
Local cortical thinning links to resting-state disconnectivity in major depressive disorder
- M.-J. van Tol, M. Li, C. D. Metzger, N. Hailla, D. I. Horn, W. Li, H. J. Heinze, B. Bogerts, J. Steiner, H. He, M. Walter
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- Journal:
- Psychological Medicine / Volume 44 / Issue 10 / July 2014
- Published online by Cambridge University Press:
- 01 November 2013, pp. 2053-2065
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Background
Local structural and metabolic as well as inter-regional connectivity abnormalities have been implicated in the neuropathology of major depressive disorder (MDD). How local tissue properties affect intrinsic functional connectivity is, however, unclear. Using a cross-sectional, multi-modal imaging approach, we investigated the relationship between local cortical tissue abnormalities and intrinsic resting-state functional connectivity (RSFC) in MDD.
MethodA total of 20 MDD in-patients and 20 healthy controls underwent magnetic resonance imaging at 3 T for structural and functional imaging. Whole-brain cortical thickness was calculated and compared between groups. Regions with reduced cortical thickness defined seeds for subsequent whole-brain RSFC analyses. Contributions of structural tissue abnormalities on inter-regional RSFC were explicitly investigated.
ResultsLower cortical thickness was observed in MDD in the right dorsomedial prefrontal cortex (PFC), superior temporal gyrus/temporal pole, middle-posterior cingulate cortex, and dorsolateral PFC. No differences in local fractional amplitude of low-frequency fluctuations were observed. Lower thickness in patients' dorsomedial PFC further directly and selectively affected its RSFC with the precuneus, which was unaffected by symptom severity. No effects of cortical thickness in other regions showing abnormal thickness were observed to influence functional connectivity.
ConclusionsAbnormal cortical thickness in the dorsomedial PFC in MDD patients was observed to selectively and directly affect its intrinsic connectivity with the precuneus in MDD patients independent of depression severity, thereby marking a potential vulnerability for maladaptive mood regulation. Future studies should include an unmedicated sample and replicate findings using independent component analysis to test for morphometric effects on network integrity.
15 - Double dividends of additional water charges in South Africa
- Edited by Pieter J. H. van Beukering, Vrije Universiteit, Amsterdam, Elissaios Papyrakis, Vrije Universiteit, Amsterdam, Jetske Bouma, Vrije Universiteit, Amsterdam, Roy Brouwer, Vrije Universiteit, Amsterdam
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- Book:
- Nature's Wealth
- Published online:
- 05 July 2013
- Print publication:
- 28 March 2013, pp 315-332
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Summary
Introduction
The purpose of this chapter is to show how double dividends could be obtained from using market instruments to tax water use in a developing country. The double dividends are namely environmental (water conservation) on the one hand, and poverty reduction dividends on the other. We apply a water tax on selected industries in South Africa to reduce demand for water, and then transfer the revenue from this tax to the poor to achieve reduction in absolute levels of poverty.
South Africa is classified as a semi-arid country. Precipitation has been fluctuating over the years with an average of 500 mm per annum, well below the world average of about 860 mm (DWAF 2002). The total flow of all the rivers in the country combined amounts to approximately 49 200 million m³ per year, while the National Water Resource Strategy estimated the total water requirement for the year 2000 at 13 280 million m3 per year, excluding environmental requirements. In addition, South Africa is poorly endowed in groundwater as most of the country is underlain by hard rock formations that do not contain any major groundwater aquifers (DWAF 2002).
While currently only about 24% of rural people have access to water on site, additional sources of water supply are environmentally, financially and politically hard to develop. At the same time, unemployment in rural areas of South Africa is extremely high, which results in severe poverty conditions in these areas.
Family history of alcohol dependence modulates functional neurophysiology in mood/anxiety disorders
- Z. Sjoerds, M.-J. van Tol, W. van den Brink, N. J. A. van der Wee, A. Aleman, A. T. F. Beekman, B. W. J. H. Penninx, D. J. Veltman
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- Journal:
- Psychological Medicine / Volume 43 / Issue 7 / July 2013
- Published online by Cambridge University Press:
- 04 October 2012, pp. 1487-1497
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Background
A family history (FH) of alcohol dependence (AD) not only increases the risk for AD, but is also associated with an increased risk for mood and anxiety disorders. However, it is unknown how a FH of AD affects neural substrates in patients with mood and anxiety disorders. In this study we examined the effects of an alcoholic FH on cognitive and emotional functions in these patients using functional magnetic resonance imaging (fMRI).
MethodIn a sample of non-alcoholic patients with depressive and/or anxiety disorders from the Netherlands Study of Depression and Anxiety (NESDA) neuroimaging study, patients with a first-degree FH of AD (FH + ; n = 31) were compared with patients without a FH (FH–; n = 77) on performance and brain activation during visuospatial planning and emotional word encoding. Results were compared with those of healthy controls (HCs) without a FH of AD (n = 31).
ResultsFH+ patients performed slower during planning with increasing task load, coupled with stronger blood oxygen level-dependent responses in dorsal prefrontal areas compared with FH− patients and HCs. FH was not associated with performance differences during word encoding, but right insula activation during positive word encoding was present in FH+ patients, comparable with HCs, but absent in FH− patients.
ConclusionsThis study demonstrates subtle impairments during planning in FH+ compared with FH− patients and HCs, whereas activation during mood-incongruent stimuli in FH+ patients was similar to HCs but not FH− patients, suggesting that the presence of a FH of AD is a useful marker for the neurophysiological profile in mood/anxiety disorders and possible predictor for treatment success.