Understanding depression and anxiety 2 of 52 http://www.open.edu/openlearn/ Tuesday 15 October 2019 About this free course This free course is an adapted extract from an Open University course. This version of the content may include video, images and interactive content that may not be optimised for your device. You can experience this free course as it was originally designed on OpenLearn, the home of free learning from The Open University: www.open.edu/openlearn/free-courses. There you’ll also be able to track your progress via your activity record, which you can use to demonstrate your learning. Copyright © 2015 The Open University Intellectual property Unless otherwise stated, this resource is released under the terms of the Creative Commons Licence v4.0 http://creativecommons.org/licenses/by-nc-sa/4.0/deed.en_GB. Within that The Open University interprets this licence in the following way: www.open.edu/openlearn/about-openlearn/frequently-asked-questions-on-openlearn. 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Head of Intellectual Property, The Open University 3 of 52 http://www.open.edu/openlearn/ Tuesday 15 October 2019 Contents Introduction 5 Learning Outcomes 6 1 Understanding the role of stress 7 1.1 What do we mean by stress? 7 1.2 Recent life events and stress 8 1.3 Early life events and stress 10 1.4 Cognition, appraisal and stress 12 1.5 Temperament, personality and heritability 13 1.6 Inheritance of temperament 14 1.7 Familial inheritance and heritability in humans 15 2 Stress and the brain 17 2.1 The operation and control of the HPA axis 19 2.2 Relating stress and depression biologically 21 2.3 Effects on the hippocampus and prefrontal cortex 22 2.4 Relating stress and anxiety biologically 23 2.5 The amygdala and generalised anxiety disorder 24 3 The life cycle model of stress 25 3.1 Adaptive value of developmental programming of stress 27 4 Insights from antidepressants 28 4.1 The monoamine hypothesis of mood disorders 28 4.2 Evidence for the monoamine hypothesis 30 4.3 Tryptophan depletion experiments 31 4.4 The neurotrophic hypothesis of mood disorders 33 4.5 Depression and levels of BDNF 33 4.6 Stress, depression and neurogenesis in the hippocampus 34 4.7 Antidepressants, BDNF levels and neurogenesis in the hippocampus 34 5 The network hypothesis of mood disorders 38 6 Genes and environment: bringing it all together 41 6.1 The serotonin transporter gene and vulnerability to stressful life events 42 6.2 Genes, environment and development 45 6.3 Epigenetic effects and human mental disorders 45 Conclusion 47 Keep on learning 48 References 49 Acknowledgements 51 4 of 52 http://www.open.edu/openlearn/ Tuesday 15 October 2019 Introduction Introduction You will notice that stress forms the backbone of this course. This is no accident, as the role of stress has attracted much attention in the last few decades, and it is now recognised as a powerful factor in the cause of emotional disorders. We start by considering what is meant by the term ‘stress’, how it is perceived, and the evidence that it is a risk factor for the development of emotional disorders. We then move on to look at the biology of stress, in particular how it affects the brain. The theme of effects on the brain is continued with a consideration of what has been learnt about the brain mechanisms underlying depression from the workings of antidepressants. Finally, we consider the interaction between genes and the environment, and how this might influence the development of emotional disorders. The related OpenLearn course Emotions and emotional disorders introduces you to the study of emotions and emotional disorders in the context of our evolutionary heritage, and goes on to consider how we might recognise emotional disorders, together with some of the problems associated with diagnosis and classification. This OpenLearn course is an adapted extract from the Open University course SDK228 The science of the mind: investigating mental health. 5 of 52 http://www.open.edu/openlearn/ Tuesday 15 October 2019 Learning Outcomes After studying this course, you should be able to: ● describe how stressful life events may be linked to emotional disorders such as depression and anxiety ● describe the main features of the physiological stress response ● evaluate the role of genetic and environmental factors in emotional disorders ● describe the different kinds of biological abnormalities that have been linked to emotional disorders. 1 Understanding the role of stress 1 Understanding the role of stress It is often the case that those developing depression or anxiety have experienced significant stress in childhood or in adult life or both. A case of work-related stress that precipitated serious depression is described in Vignette 1. Vignette 1 An experience of stress The following extract is taken from an interview with a 43-year-old woman, who was diagnosed with depression at 40. Background: Is a divorced part time carer. Before her depression and suicide attempt she was a workaholic in a job that was becoming more demanding. Her depression required hospitalisation. ‘Work had always been really important to me and I’m more like a perfectionist. So everything has to be a 100%, you know, and all that. And I got made promotion several times with my job, and then suddenly, I think like many companies, people started making people redundant, and requesting people to take on more and more and more. In the end I was doing the job 5 people used to do. I was enjoying it. I enjoyed it to the point where it was just getting, physically it was just getting an impossibility. But I’d always loved my job, but it was then becoming that I was away 5, 6 days a week, getting home and I couldn’t get away from work basically, because I would get back here and there would be faxes and messages and goodness knows what and … A lot of my job was travelling a lot I was covering a huge area, not just the UK. And one day I just sort of came home after I had been away for a week, parked my car outside, sat on the pavement and just broke down, basically.’ (Health Experience Research Group, 2010) 1.1 What do we mean by stress? We tend to think of ‘stress’ as a state of demand that is likely to stretch us to breaking point, and hence as a bad thing, to be avoided. An image of stress this brings to mind is pulling on a chain with increasing force: sooner or later the chain will break at the weakest link, leading to collapse. However Hans Selye, the distinguished Austro-Hungarian endocrinologist who developed the concept of stress in the 1930s, felt this was a very one-sided view – he regarded stress as ubiquitous and vitally important, calling it ‘the salt of life’ (Selye, 1978 [1956]). Selye distinguished two kinds of stress: Within the general concept of stress … we must differentiate between distress (from the Latin dis = bad, as in dissonance, disagreement), and eustress (from the Greek eu = good, as in euphonia, euphoria). During both eustress and distress the body undergoes virtually the same nonspecific responses to the 7 of 52 http://www.open.edu/openlearn/ Tuesday 15 October 2019 1 Understanding the role of stress various positive or negative stimuli acting upon it.