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This week’s Said&Dunn post is by guest blogger, Megan Skelton. Megan is a PhD student and member of The Emotional Development, Interventions and Treatment (EDIT) lab team at King’s College London. The EDIT lab focuses on the role of genetic, cognitive, and environmental factors in the development and treatment of emotional difficulties, such as anxiety and depression.  As part of their recent “A-Z” series, their blog featured a post for each letter of the alphabet, covering topics that span the interests of their group. This post is adapted from their D post (D is for Depression).  


What are the symptoms of depression?

While everyone experiences sadness and possibly even bouts of depression at different points in their life, perhaps following loss of a loved one, people with depression experience symptoms that go on for longer, are more severe, and/or interfere with the activities that make up normal daily life.

All people with depression experience two core symptoms: (1) A persistent low mood; and (2) a loss of interest or pleasure in previously enjoyable activities.

There are different types of depressive disorders, with eight diagnoses in the current Diagnostic and Statistical Manual, including major depressive disorder and persistent depressive disorder (dysthymia). Depressive disorders are distinct from bipolar disorder where people also experience episode(s) of mania. 

When people talk about clinical depression, they are usually referring to major depressive disorder, which is the most common type of depression. A diagnosis requires one or both of the two core symptoms (persistent low mood and loss of pleasure/interest), as well as other symptoms which are much less often discussed or represented in portrayals of depression, but which have profound impact on daily functioning and well-being. 

For example, some individuals experience significant weight loss or gain due to a disrupted appetite, find themselves unable to sleep (insomnia) or sleep excessively (hypersomnia). Additional symptoms may be feelings of guilt, low self-esteem or irritability, as well as suicidal thoughts. Given this range of symptoms, it is possible for two people with a depression diagnosis to present very differently. There can also be differences in terms of how long the symptoms go on for, and how severe they are. Depression is usually experienced in episodes, with periods of remission (where the individual experiences much lower levels of symptoms) in between. Some people have just one episode in their life, but many suffer from recurrent episodes. For others their depression might be persistent without periods of remission.

This storyboard gives a very insightful first-hand account of what it feels like to live with depression:

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How common is it and when does it typically first start? 

Globally, depressive disorders affect approximately 13% of individuals across their lifetime. However, prevalence varies across cultures, with one study reporting prevalence rates ranging from 3% in Japan to 16.9% in the United States. Women are at approximately twice the risk of depression compared to men and this is observed across cultures. Interestingly, this sex difference does not emerge until adolescence.

The onset of depression is on average (median) early- to mid-twenties. However, this is highly variable, with child, adolescent and older age depression also reported. 

Depression is also implicated in around 2 million deaths a year through suicide and increased risk of diseases such as cardiovascular disease. Given these numbers, it is no surprise that depression is the fifth leading cause of the global burden of disease and first leading mental health cause worldwide. 


Does genetics play a role in shaping who is at risk for depression?

The heritability of a trait or disorder is an estimate of the extent to which individual differences in the population are explained by genetic differences between people. Twin studies estimate the heritability of depressive disorders at approximately 40%. Progress in understanding the specific genes involved in depression has been somewhat slow, but a recent genome-wide study by the Psychiatric Genomics Consortium in which [both the Dunn and EDIT labs] participated has made great strides forward, identifying 44 relevant genetic variants that predict risk for depression. 

What about the role of the environment?

Environmental factors also contribute to the onset of depression. Stressful life events and trauma have been extensively studied, both in childhood and adulthood, in association with depression. Events such as financial problems or divorce often precede a depressive episode, but there is a great deal of individual variation in the responses to such experiences. 

One factor that has been demonstrated to increase vulnerability to stressful life events in adulthood is the loss of a parent during childhood, with the risk of developing depression increasing significantly when this occurs in early childhood. Furthermore, childhood trauma, such as abuse or neglect, is an especially strong risk factor for depression in later life, potentially due to the impact of these extremely stressful events on the developing central nervous system.


What treatments are available?

Similar to anxiety, there are various treatments available for depression. The National Institute for Health and Care Excellence (NICE) recommends psychological (talking) therapies and antidepressant medication, independently or in combination. The National Alliance on Mental Illness (NAMI) describes alternative treatments options, such as cognitive behavioral therapy and support groups, and holds online discussion groups, which can be a great way to manage recovery, find support, and learn more about mental health conditions. NAMI also brings different programs and support groups to a wide variety of community settings, from churches to schools, across the country. As no single treatment will work for everyone, mental health researchers are striving to develop new treatments and ways to predict individual response to different types of treatment.


If I’m experiencing depression or have a loved-one who is experiencing depression, what should I do?

If you have been experiencing symptoms of depression, visit your primary care doctor to discuss your options. There are also many useful services online, such as information on local peer support groups and self-help techniques, as well as confidential helplines if you want someone to talk to. We have listed some of them below.


Confidential support for people experiencing distress, struggling to cope, or at risk of suicide. 1 (800) 273-TALK 

Substance Abuse and Mental Health Services Administration (SAMHSA):

A confidential and anonymous source of information for persons seeking treatment facilities in the US. It provides a free behavioral health treatment services locator online. 1 (800) 662-HELP (4357) 


Suicide Prevention Lifeline:

The Lifeline provides 24/7, free and confidential support for people in distress, prevention and crisis resources for you or your loved ones, and best practices for professionals. 1-800-273-88255 

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To view the original version of this post, please click here. You can also read more pieces by Megan Skelton here.