What is Depression?
Depression is a mood disorder often referred to as clinical depression, major depression, or major depressive disorder. It’s characterized by a persistent low mood, during which the sufferer has a feeling of sadness and/or low self-worth. Although periods of sadness are common in everyone, the symptoms of major depression become so severe that they interfere with the sufferer’s daily routines, social functioning, and personal relationships. In many cases, the symptoms become so pervasive that they threaten the integrity of relationships, employment, or financial well-being, and suicidal tendencies are not uncommon among depression sufferers.
Symptoms of Depression
There are many symptoms of major depression, and not all of them need to be present for a sufferer to be diagnosed with the disorder. In general, the symptoms must have been present for at least two weeks before a diagnosis can be made.
The most common symptoms of depression include:
- Persistent sadness
- Feelings of emotional flatness or disengagement
- Feelings of low self-worth or helplessness
- Persistent hopeless, morbid, or pessimistic feelings
- Feelings of anxiety
- Problems with concentration
- Chronic irritability or angry outbursts
- Lack of interest in activities that were once pleasurable
- Chronic fatigue or lower than normal energy levels
- Restlessness or excessive energy
- Problems with sleep, including insomnia or sleeping too much
- Appetite changes that result in changes, either decreases or increases, in weight
- Suicidal thoughts or suicide attempts
Clinicians will sometimes diagnose Subsyndromal Symptomatic Depression (SSD) in patients who have two or more of these symptoms that aren’t severe enough in-depth or duration to warrant a diagnosis of major depression.
Subtypes of Depression
Some depressive disorders are characterized by a unique cluster of symptoms or a specific cause of the symptoms. These types of depression include:
- Postpartum depression. This disorder is defined by periods of major depression in a woman during pregnancy or soon after giving birth. The symptoms are more severe than typical postpartum mood fluctuations, and the result can be life-threatening.
- Psychotic depression. This disorder is diagnosed when symptoms of major depression are accompanied by symptoms of psychosis, such as hallucinations or delusions.
- Seasonal affective disorder. Thought to be caused by decreased levels of sunlight during the winter months, this disorder manifests its symptoms during the winter, and the symptoms typically subside in the spring. Diagnosable seasonal affective disorder occurs in the patient consistently year after year.
- Persistent depressive disorder. This disorder, also called dysthymia, is characterized by periods of depression lasting more than two years. The depression may increase or decrease in severity over that period, but it never goes away.
What Causes Depression?
Doctors and researchers have not yet determined the exact causes of major depression, but they have identified several risk factors that increase an individual’s likelihood of developing the disorder.
- Genetic Predisposition. People with a family history of depression are three times more likely to be diagnosed with major depression than those with no family history of the disorder. Researchers have begun to identify genes that may play a role in the development of depression. Still, the exact genetic mechanism that makes some people more prone to developing the disorder has not yet been pinpointed.
- Biological Causes. Some hormonal imbalances, such as the abnormal cortisol levels experienced by sufferers of Cushing’s Disease, have been linked to depression.
- Environmental Risk Factors. While poor sleep habits are a common symptom of major depression, there is some suggestion that lack of adequate sleep may also be a risk factor for developing depression.
- Drug Abuse. Excessive alcohol consumption or the abuse of drugs or other substances often occur in tandem with major depression.
- Other Illnesses. Chronic severe illnesses such as Parkinson’s disease, diabetes, heart disease, obesity, or chronic pain are often accompanied by major depression. The depressive moods may be caused by the disease’s effects on the patient’s life or caused by biological changes in the patient’s body as part of the disease.
- Social Risk Factors. Major life events, such as divorce, unemployment, or the loss of a loved one, often trigger depressive symptoms.
Is Depression Hereditary?
Studies of families in which major depressive disorder occurs strongly suggest that a genetic component may be a critical factor in developing the condition.
- In the general population, the rate of occurrence of major depressive disorder appears to be relatively consistent in all cultures worldwide, with the rate of occurrence falling somewhere between 8% and 12%.
- Some studies have found that when one twin has the disorder, the other twin also has the condition at a rate of as high as 38%.
- Two studies have found that women seem to be much more likely to inherit the disorder than men. The studies showed that women seem to inherit the condition at a rate of about 40%, while men inherit it at a rate of about 30%.
How is Depression Detected?
Major depressive disorder is not very common in children before adolescence, but the condition becomes much more prevalent in adolescents. Some studies have suggested that as many as one in five adolescents will have experienced symptoms of depression before they’re out of their teen years. Once they have experienced symptoms, more than half of them will experience a recurrence of symptoms within two years, and fully 70% will experience a relapse within five years.
However, major depression is often difficult to spot in adolescents. Depressive episodes may resolve themselves without treatment, half the time within two months. The first signs noticed are often physical symptoms, such as fatigue or aches and pains, which may be misdiagnosed.
Potential early signs of major depression in young people include:
- Separation anxiety (in pre-adolescents)
- Poor sleep habits
- Decline in grades
- Withdrawal from social activities
- Anger or irritability
- Unexplained aches or pains
- Symptoms of ADHD
- Substance abuse
How is Depression Diagnosed?
Diagnosis of major depressive disorder begins with determining that the patient has a cluster of the symptoms that define the condition and that the symptoms have been present for at least two weeks. A doctor will begin with a physical exam to rule out biological problems that may be causing symptoms that mimic those of depression; this exam may include lab tests.
If, after these exams, the doctor suspects that major depression is the cause of the symptoms, they may recommend a psychological or psychiatric assessment to solidify the diagnosis further.
Diagnostic steps may include:
- A physical exam. This exam is focused on ruling out physical conditions that could be causing the symptoms.
- Blood tests. These tests will look at the patient’s blood chemistry for thyroid function, electrolyte imbalances, anemia, chronic infection, and cancer. Screenings for drugs and alcohol may also be conducted to rule out symptoms caused by substance abuse.
- Psychological assessments. These assessments may take the form of questionnaires or talk sessions with a mental health professional to assess the patient’s mood, mental state, and mental health history. Family members or caregivers may also be asked to participate in these assessments.
The psychological assessment results will be compared to the diagnostic criteria for major depression in the Diagnostic and Statistical Manual of Mental Disorders. Comparing these criteria will help a psychiatrist decide whether the symptoms indicate depression, another psychiatric problem, or a coincidence of depression and another condition.
How is Depression Treated?
Major depression currently has no known reliable cure, but a combination of medications and psychotherapy is often effective at reducing the severity of symptoms in many patients.
Several different medications may be used to treat and manage the symptoms of major depression. Individual medication plans depend on the patient’s age, the patient’s responsiveness to treatments, and the severity of their symptoms.
- Selective serotonin reuptake inhibitors (SSRIs). These drugs work by increasing serotonin levels, a neurotransmitter chemical in the brain. Higher levels of serotonin seem to help to elevate mood in many people. Common SSRIs include citalopram, escitalopram, fluoxetine, paroxetine, sertraline, and vilazodone.
- Serotonin-norepinephrine reuptake inhibitors (SNRIs). These drugs work similarly to SSRIs in that they increase serotonin levels, but they also increase the level of norepinephrine, another neurotransmitter.
- Other antidepressants. Drugs such as bupropion, mirtazapine, nefazodone, trazodone, and vortioxetine work differently from SSRIs or SNRIs but can effectively treat depression. Tricyclic antidepressants such as imipramine, nortriptyline, amitriptyline, doxepin, trimipramine, desipramine, and protriptyline tend to have more problematic side effects, so they’re less commonly used to treat depression unless the patient has already shown no improvement from SSRIs.
- Monoamine oxidase inhibitors (MAOIs). Drugs such as tranylcypromine, phenelzine, and isocarboxazid can have potentially serious side effects; they are typically only used to treat depression when other medications don’t work.
A combination of medication and psychotherapy is often the most effective approach to controlling the effects of depression. The most common therapeutic approach is cognitive behavioral therapy (CBT). This process helps the patient identify a pattern of harmful thoughts and construct strategies and solutions for dealing with them that don’t interfere with functionality.
In some severe cases of depression, when more traditional medications and therapies are ineffective, some providers try alternative treatments, such as:
- Electroconvulsive Therapy. In this therapy, an electric current is passed through the brain, disrupting neurotransmitter chemicals’ function. This therapy is usually used on patients who don’t respond to medication, can’t take medication, or are deemed to be at high risk for suicide.
- Transcranial magnetic stimulation (TMS). This therapy transmits intermittent electromagnetic pulses through the brain in an attempt to stimulate nerve function. This therapy, too, is usually used on those who don’t respond to medications.
How Does Depression Progress?
In some cases, depressive episodes can resolve independently, but depression is very likely to recur in most people. When left untreated, depressive symptoms can become more severe and result in significant complications, including:
- Weight gain and its consequences
- Substance abuse
- Anxiety disorders
- Panic disorders
- Relationship dysfunction
- Employment or school dysfunction
- Social anxiety
However, with treatment, symptoms of depression are very often controlled within six months to a year, and continued treatment can be very effective at preventing recurrence.
How is Depression Prevented?
There is no way to prevent major depression, but prompt diagnosis and an effective treatment plan can help to manage symptoms and prevent the most severe of the disorder’s consequences. In many cases, treatment may be stopped when symptoms resolve, but continuing an effective treatment plan may prevent recurrences.
It’s essential for those diagnosed with major depression to seek regular evaluation from their mental health providers and stick to any prescribed medication plan. Abruptly stopping the use of an antidepressant can be especially dangerous, as it can cause withdrawal symptoms and a return to a severe depressive state.
Depression Caregiver Tips
Caring for someone with major depression can be very frustrating and exhausting. Many of the disorder’s symptoms manifest in emotionally taxing ways for the sufferer’s loved ones. Those who are close to someone with depression are at risk of developing depression themselves.
Caregivers for someone with major depression should consider these tips to help the sufferer and themselves to cope with the disorder:
- First, learn as much as possible about the disorder.
- Don’t expect the sufferer to get better on their own.
- Seek out appropriate professional treatment for the sufferer.
- Do everything possible to support the sufferer in the pursuit of treatment.
- Try not to take outbursts of anger or frustration as a personal attack, but see it as a symptom of the disorder.
- Be supportive of the sufferer and acknowledge any improvements.
- Find a support group for caregivers.
- Take time away from the sufferer when possible.
Many people with depression also suffer from other brain and mental health-related issues, a situation called co-morbidity. Almost all mental disorders are significantly more common in people with depression, and when depression is co-morbid with another disorder, both disorders are often more severe. Here are a few of the disorders commonly associated with depression:
- More than half of people who have had depression in their lifetime have also experienced an anxiety disorder.
- About 40% of people with a history of depression also struggle with alcohol use disorder, and about 17% suffer from another substance use disorder.
- People with depression are at an increased risk of suicide.
- Personality disorders are common in people with depression. Of these, borderline personality disorder is the most common.
- Depression is also commonly associated with neurological disorders such as epilepsy and other medical conditions such as muscular dystrophy.
Depression Brain Science
Current research on major depressive disorder focuses on many different areas, from finding the genetic source of some forms of the condition to identifying the most effective therapies, both physical and psychological. Scientists are especially interested in understanding the brain chemistry involved in depression more fully so that more effective medications can be developed, particularly for those who don’t respond well to existing drugs.
- The Food and Drug Administration has recently approved the anesthetic ketamine as a treatment for major depression. Scientists were able to develop a form of the well-established drug administered via a nasal spray, and the treatment shows promise for treating medication-resistant depression.
- Researchers use imaging technologies to look at a part of the brain called the hippocampus, which is smaller than usual in some sufferers of depression. It is possible, scientists think, that the hippocampus in these people does not produce enough new nerve cells in the brain, leading to a depressed mood.
Scientists are working on several research projects to expand on what is known about depression. The research will improve knowledge about the factors that increase the risk of depression and the causes and best treatments and help people living with Depression and their caregivers.
We are currently gathering the information required to support projects such as Neurobiological Underpinnings of Placebo Response in Depression and Neuroimaging in Patients Undergoing TMS for Depression (NIPUTFD).