Depressive Disorders (Depression)

Key takeaways

• Depressive disorders are common mood disorders, characterized by a low mood and a loss of enjoyment in normal activities

• Depressive disorders are usually caused by a combination of factors, including genetic predisposition and environmental or social triggers

• Depression can be treated with psychotherapy and/or medication. It can take trial and error to find the right therapy modality or antidepressant to suit you

Understanding depression

Depression is a mental health condition characterized by low mood, sadness, and difficulty finding joy. It can feel like carrying a heavy emotional weight and can create the feeling of barriers between the depressed person and their loved ones.

Most people experience a low mood from time to time, especially when something isn’t going well in their lives or they have suffered some kind of loss or disappointment. Depression occurs when those short-term feelings remain and become a long-term emotional state.^[1]

The prevalence of depression

Depression is a common disorder worldwide, affecting around 350 million people.^[2]Within the US, approximately 21 million adults experienced a period of depression in 2021. That’s 8.3% of all Americans over the age of 18.^[3]

Just over 18% of Americans report having been diagnosed with depression at some point in their lives.^[4]

Depression by demographic

There are some patterns in who is diagnosed with depression. Women are almost twice as likely to receive a diagnosis of depression as men.^[5]

Young people are more likely to report having experienced depression within the last 12 months than other groups, with 18.6% of Americans aged 18-25 having a recent depressive episode.^[3]

People with more than one race had higher rates of depressive episodes than other racial groups (13.9%).^[3]

What causes depression?

There is no single or simple cause of depression. It arises from a combination of genetic, biological, environmental, and social factors.

People are more likely to experience depression if they^[6]

• Have close family members who suffer from depression

• Have experienced adverse or stressful life events, especially during childhood

• Have low levels of social, emotional, and practical support

• Have certain medical conditions, including dementia, MS, and stroke

In addition to increasing the lifetime risk of depression, stressful life events such as a bereavement or being the victim of violence can act as a trigger for the condition.

There is some evidence that late-onset depressive disorders may have less of a genetic component than those with onset in adolescence or early adulthood.^[7]

Depression is associated with changes in neurotransmitter levels, and pharmacological treatments often aim to rebalance those levels. Neurotransmitters thought to play a role in depression include^[7]

• Serotonin

• Norepinephrine

• Dopamine

• Glutamate

• Brain-derived neurotrophic factor (BDNF)

Types of depression

Although people often talk about ‘depression’, there are many different disorders that lead to symptoms of depression. Collectively, these are known as mood disorders.^[8]

Unipolar vs bipolar depression

Previously, depressive disorders were classified as either unipolar or bipolar. Unipolar depression occurs when someone only has a depressed mood. Bipolar depression (as it was then called) occurs when someone has periods of abnormally low mood and periods of abnormally elevated mood.

There are significant differences between unipolar and bipolar mood disorders, including how strongly they are inherited, the demographics they affect, and how patients usually respond to medication.^[1]The term ‘depression’ is usually used to refer to unipolar depression (now known as depressive mood disorders).

Major depressive disorder (MDD)

Major depressive disorder (or major depression) is what most people would think of as depression. It is characterized by a period of very low mood and a loss of interest in (or enjoyment from) normal activities, such as hobbies.^[9]It must last at least 2 weeks and have several other symptoms.

Persistent depressive disorder (dysthymia)

Persistent depressive disorder is diagnosed when someone has a long period of low mood that doesn’t fulfill the criteria for major depression.^[10]Although the symptoms are less severe than in major depression, persistent depressive disorder is a serious condition.

Premenstrual dysphoric disorder (PMDD)

Premenstrual dysphoric disorder is characterized by a period of low mood or emotional disturbance linked to the menstrual cycle. It typically lasts for a few days and finishes at the onset of menses (the start of a period).^[11]

Perinatal depression

Perinatal depression (previously referred to as postnatal depression or the ‘baby blues’) affects parents either during pregnancy or the first year following the birth of a child.^[12]

Although perinatal depression is widely recognized in women, it also affects fathers. Men are more rarely affected by perinatal or postpartum depression, however.^[13]

Seasonal affective disorder (SAD)

SAD is a type of depression that is closely linked to the seasons. The most common form of SAD involves a predictable period of low mood that begins in the late fall or early winter, with patients feeling better in the spring and summer months. Some patients experience a reversal of this pattern, with low mood during the summer and remission during the winter months.^[14]

Depressive disorder due to another medical condition

Depressive disorder due to another medical condition is a diagnosis given when someone has a period of very low mood that doctors believe is due to another illness they have. Possible causes include diseases that affect the brain (for example, schizophrenia, Alzheimer’s, or a stroke), hormone levels (for example, hypothyroidism), or that cause distress or suffering (for example, cancer or chronic pain).^[15][16]

Disruptive mood dysregulation disorder (DMDD)

DMDD is a depressive disorder that affects young people. In common with other types of depression, people with DMDD have a strong negative mood, but this manifests differently. They experience high levels of irritability and angry outbursts, which are sometimes described as temper tantrums.^[17]

Depression symptoms

Symptoms of depression can be divided into different categories.

Emotional symptoms of depression

Most of the symptoms people associate with depression are emotional symptoms. These include^[18]

• Feeling sad or emotionally ‘flat’

• Not feeling pleasure in things that they used to enjoy (anhedonia)

• Feeling worthless or lost

• Feeling guilty or irritable

• Feeling lethargic, or as if things are pointless

Behavioral symptoms of depression

Behavioral symptoms of depression are things that the person does. These are things that other people might be able to see. Examples include^[7]

• Changes in eating patterns (either increased or decreased)

• Changes in sleeping patterns (either increased or decreased)

• Crying

• Social withdrawal

Cognitive symptoms of depression

Some symptoms of depression concern the way someone thinks or the beliefs they hold about the world. These include^[19][20]

• Expecting negative outcomes

• Focusing on upsetting past events (rumination)

• Poor motivation and concentration

• Difficulties with memory

• ‘Brain fog’ and slowed thinking

• Difficulty planning future events and making decisions

• Thinking about suicide and death (suicidal ideation)

Depression and suicide

People suffering from depression have higher mortality rates than the general population, and one major cause of this is their higher suicide rates.^[21]Depression is linked to 40,000 suicides every year in the US, and estimates suggest that around 31% of patients with MDD will make at least one suicide attempt in their lives.^[7][22]Most at risk are men, those who misuse drugs or alcohol, and anyone who has previously attempted suicide.^[23]

People with depression may also experience thoughts about suicide (suicidal ideation), which can be separate from any plan to take their own life (passive ideation).^[24]They may also experience intrusive thoughts about suicide or self-harm, often without wanting to do so, which can feel especially difficult.

People who are close to someone with depression sometimes worry that asking about suicidal thoughts or feelings might increase the risk of their loved one harming themselves, but this isn’t the case. Allowing someone to talk openly about suicidal ideation can be helpful and reduce their risk.^[25]

Suicidal thoughts and feelings are a serious symptom of depression and should never be dismissed as attention-seeking or a cry for help. Anyone experiencing these symptoms should seek urgent medical help. In cases where there is no imminent danger, it may be sufficient to make an urgent appointment with a healthcare provider. If there is the potential for immediate harm, however, you may need to call 911.

Helplines can offer support and guidance to someone who is suicidal, or to those who are worried about the risk of suicide in someone they are close to. The Suicide & Crisis helpline is available 24/7. Call or text 988 to access it.

Diagnosing depression

To diagnose depression, a doctor or medical practitioner will ask you about a variety of symptoms, including how often they occur and how long you have had them. For MDD, you will need to have experienced at least 5 symptoms from the following list, including either anhedonia or depressed mood. These symptoms will have needed to last for the majority of the day, almost every day, for at least 2 weeks.^[6][18]

• Anhedonia (a loss of interest or pleasure in activities)

• Depressed mood

• Problems with sleep

• Feelings of guilt or thoughts of worthlessness

• Changes to energy levels or fatigue

• Difficulty concentrating or other attentional problems

• Appetite or weight changes

• Psychomotor disturbances, including slowed movements or agitation

• Suicidal thoughts

When and how to seek help

As many as 60% of people with depression do not seek help for their symptoms.^[7]This can be due to stigma, concerns about how a diagnosis might affect career opportunities, an expectation that they should ‘push through’ their symptoms, or a belief that nothing can be done.

Persistent low mood isn’t something anyone should struggle through, especially when there are many effective treatments to try. Talk to your doctor or medical practitioner if you experience a persistent low mood for more than two weeks or if your mood is making it difficult to carry out everyday activities, such as work or hobbies.

If you experience suicidal thoughts, even if you don’t plan to act on them, don’t wait. Speak to your doctor immediately.

Treatment options for depression

Depression is treatable, though this doesn’t always mean that patients achieve complete remission. The relapse rate is also stubbornly high, and patients may need to try different treatment options before they find one that suits their needs.

Psychotherapy options for depression

Psychotherapy can be an effective treatment for depression. You will usually have one-to-one conversations with a therapist or counselor to discuss the problems you’re having and help you deal with them.

There are different approaches to psychotherapy, but research suggests that the most important factor in success is the relationship of trust you develop with your therapist.^[26]If one therapy modality or therapist doesn’t work for you, consider looking for someone different.

Cognitive behavioral therapy (CBT)

The most commonly used type of psychotherapy for depression is CBT.^[27]This therapy attempts to address negative beliefs patients have about themselves, the world, and the future.

Patients are encouraged to challenge their beliefs, look for alternative evidence, and may be assigned tasks, such as writing down negative thoughts, to attempt before their next session.

Interpersonal therapy (IPT)

IPT moves the focus of therapy away from the patient’s thoughts and beliefs and instead focuses on improving their relationships with the people around them. This can help patients overcome the social withdrawal that often appears as a symptom of depression and helps them create a supportive social structure as they recover.^[28]

Psychodynamic therapy

Psychodynamic therapy attempts to explore relationships and events in a patient’s past that might have contributed to their current depression. This enables patients to develop insight into how their experiences contribute to their emotions.^[29]

Medication treatment for depression

The different medications used to treat depression are commonly referred to as ‘antidepressants’, but this includes many different medications that work in slightly different ways.^[7]

Selective serotonin reuptake inhibitors (SSRIs)

SSRIs increase the amount of serotonin in the central nervous system (CNS). They are considered relatively safe medications and are especially useful for late-onset depression. SSRIs are thought to be effective for 60-70% of patients.^[30]

Common SSRIs used to treat depression include citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, vilazodone, and vortioxetine.

Serotonin/norepinephrine reuptake inhibitors (SNRIs)

SNRIs increase the amount of both serotonin and norepinephrine in the CNS. They are often used when SSRIs have not been effective or if patients have particular problems with fatigue or pain.^[7]

Common SNRIs used to treat depression include venlafaxine, desvenlafaxine, duloxetine, and levomilnacipran.

Atypical antidepressants

Atypical antidepressants are those that don’t fit neatly into other categories. Each of these drugs has a different mechanism of action.^[30]These are sometimes used alone or in combination with other medications and psychological treatments.

Common atypical antidepressants used to treat depression include bupropion, mirtazapine, nefazodone, and trazodone.

Serotonin-Dopamine Activity Modulators (SDAMs)

SDAMs work by modulating the levels of both serotonin and dopamine in the central nervous system (CNS). They aren’t usually offered as a single treatment. Instead, they are used to improve the effectiveness of other antidepressants.^[31]

Common SDAMs used to treat depression include brexpiprazole and aripiprazole.

Tricyclic antidepressants (TCAs)

Tricyclic antidepressants can be highly effective, but they are used less often than other antidepressants because they can cause unpleasant side effects and are more toxic in overdose.^[7]

Common TCAs used to treat depression include amitriptyline, clomipramine, desipramine, doxepin, imipramine, nortriptyline, protriptyline, and trimipramine.

Monoamine oxidase inhibitors (MAOIs)

MAOIs are often used when someone has an anxiety disorder, as well as for depression. MAOIs can interact with a lot of other medications and can come with uncomfortable side effects, so they are used with caution.^[23]

Common MAOIs used to treat depression include isocarboxazid, phenelzine, selegiline, and tranylcypromine.

Alternative depression treatment and study

Given the high prevalence of depression and high relapse rates, research continues into other therapies that might help patients. Here are some of the less common treatments or areas of current investigation.^[33]

Neuromodulatory treatments

Neuromodulatory treatments for depression attempt to relieve symptoms by changing the activity of neurons in the brain. They can use electrical impulses, magnetic fields, or other stimuli.

Electroconvulsive therapy (ECT) is sometimes used for people with very severe depression that has not responded to other forms of treatment.^[34]In ECT, an electrical stimulus is used to induce a seizure in a patient under anesthesia. While it is generally a safe procedure, it can cause unacceptable side effects, particularly memory loss

Repetitive transcranial magnetic stimulation (rTMS) uses magnetic fields to stimulate specific areas of the brain. It is not yet known whether it is as effective as ECT, but it has mild side effects and can feel less invasive to patients.

Light-based therapies, including photobiomodulation and bright light therapy, use lights of specific wavelengths to reduce the symptoms of depression. The evidence for these is currently weak, but they have few side effects and many patients with SAD find them especially helpful.

New medications

Several drugs are currently being investigated to discover whether they can provide an effective treatment for depression. These include psychedelics, such as psilocybin, ketamine, certain antibiotics, and neuropeptides.

As these are currently being researched, it is not yet clear whether they will be either safe or effective, or which patients might benefit most from using them.

Herbal remedies

Herbal remedies and supplements remain popular among people with depression, especially those who do not want to seek a diagnosis from their doctor. Both St John’s Wort and vitamin D are widely used.

Although these may be natural or routine dietary supplements, patients should still take care. They can have side effects, and St John’s Wort, in particular, can have dangerous interactions with some antidepressants.^[35]

Always speak with your doctor or a healthcare professional before taking herbal remedies or supplements, especially if you are on other medications.

Depression contacts and resources

Depression can be an isolating condition, leaving people feeling as though they have nowhere to turn, or even as if they are a burden to the people around them. Even though this isn’t true, it can make it difficult for people with depression to reach out and find the resources they need.

SAMHSA (Substance Abuse and Mental Health Services Administration) offers a wide range of resources, including helping you to locate treatment and offering self-help guides.

SAMHSA also operates the 988 crisis helpline for anyone experiencing a mental health crisis or who is feeling suicidal. This is a confidential service that’s available 24/7 and also offers help to people who are worried about a loved one’s mental health. You can call or text 988 at any time.

The Anxiety and Depression Association of America (ADAA) can help you find treatment options, as well as offer free webinars and peer support, allowing you to connect with others who are experiencing similar problems.

Another peer support option is the Depression and Bipolar Support Alliance (DBSA). They provide downloadable resources to help you manage your mental health, as well as both in-person and online support groups.

Your doctor, mental health professional, or other healthcare staff are available to help you with your depression. Many other community support workers, school staff, and even emergency first responders are trained to help point you in the right direction for support.

For any mental health emergency where someone is at risk of imminent harm, you can always call 911.

Conclusion

Depression can be a debilitating medical condition that leaves patients feeling hopeless, but it is treatable. Seeking help early gives you the best chance of overcoming the illness and reduces the time you spend suffering under this burden.