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Depression: Overview

Last Update: June 18, 2020; Next update: 2023.


We all feel sad or lethargic every now and then. And we have all felt down or even desperate at some point in our lives. These phases are a normal part of life, and people usually feel better again after a while. Things are different for people who have depression. Their sadness and negative thoughts last longer and overshadow all of their thoughts and actions. Depression can arise without any triggering events or for no apparent reason. People often feel like they're stuck in a deep, dark hole. They feel cheerless, worthless, and lack motivation and self-confidence. This can make it difficult to do everyday things like going to work or studying. Friends, family and hobbies are often neglected. They don't sleep well.

Depression can also make family and friends feel worried, anxious and helpless. Often they want to help but don't know how. It's not always easy for them to tell whether it's a passing phase or a serious illness.


People who have depression fall into an emotional black hole for weeks or months, and often can't see any way out. Different people experience depression differently:

  • Some mainly feel sad and down. Everything seems pointless. Nothing and nobody can lift their spirits.
  • Others don't feel sad, but instead have a deep emptiness inside, feel exhausted and emotionally numb, and lack the motivation to do anything.
  • And others mainly suffer from agonizing worries, fears and anxiety.

Many have trouble sleeping. Particularly in older people, depression can lead to physical symptoms such as weight loss or inexplicable pain.

Depression not only causes listlessness, it can also make people more excitable. For instance, in bipolar depression (manic depressive disorder), people have depressive phases followed by euphoric phases where they lose touch with reality.

Causes and risk factors

The cause of depression is not exactly clear. It is thought that various things play a role. These include biological factors, psychological factors, a person’s individual circumstances and particular events in their lives. Here are some examples of things that can make depression more likely and influence the course of the disease:

  • Genes: People have an increased risk of depression if other people in their family have had depression.
  • Difficult experiences: for instance, abuse or neglect, the end of a relationship or the death of a loved one.
  • Chronic anxiety disorders in childhood and puberty, combined with low self-esteem and insecurity.
  • Biochemical changes: The metabolism in the brain has been found to be different in people with depression, and nerve signals travel more slowly. Certain chemical messengers and hormonal changes can also play a role.
  • Physical medical problems such as strokes, heart attacks, cancer or an underactive thyroid.
  • Difficult life circumstances: for instance, persistent stress or loneliness.
  • Lack of light: The dark autumn and winter months can lead to depression in some people.


Depression is one of the most common mental health problems. It is estimated that 16 to 20 out of 100 people will have depression or a chronic low mood (dysthymia) at least once in their lives. Women are affected more than men, and it is more common in older people.


The course of depression can vary. In some people things get better after a few weeks or months – sometimes even without treatment – and the depression doesn't come back. About half of all people who are treated for depression feel a noticeable improvement in symptoms after about three to six months.

Many have regular episodes of depression followed by depression-free phases. Others have depression over a long period of time, with severe phases and less severe phases, while in some people the symptoms stay the same. If the symptoms last longer than two years, it is considered to be chronic depression.

If the symptoms of depression come back within six months after you last had them, it is called a relapse. If you have another episode of depression more than six months after the last one, or even years later, it is called recurrent depression.


Depression makes people feel and behave differently than they used to. They often feel like it's their own fault, and are plagued by self-doubt. Many say they have feelings that they can no longer control or cope with. They may also think about killing themselves (have suicidal thoughts). In most cases they don't actually take that step, but unfortunately not always.

People often become withdrawn, avoid social contact and hardly leave the house any more. They might start abusing alcohol, medicine or other drugs. These things can make the depression carry on longer, and could make it worse. It is often only possible to stop this vicious circle with the help of other people.


Some people have such severe depression that they can't summon the energy to get help themselves. Then it's important for their family and friends to offer support and, for instance, take them to see a doctor.

To find out whether someone has depression, psychotherapists do two things: They ask about symptoms that could be signs of depression. They also try to rule out other illnesses or health problems that cause similar symptoms. To do so, the doctor might need to perform physical examinations or tests too.

The typical symptoms of depression can be divided up into “core symptoms” and “secondary symptoms.”

The core (main) symptoms include:

  • Low mood, sadness, feeling down
  • Lack of interest and joy
  • Lack of motivation and getting tired quickly, even after gentle activities

The secondary symptoms include:

  • Loss of appetite
  • Trouble sleeping
  • Difficulty concentrating and making decisions
  • Low self-esteem
  • Feelings of guilt
  • Negative and pessimistic thoughts about the future
  • Suicidal thoughts or suicide attempts

If someone has several core and secondary symptoms over a period of two weeks or longer, they are diagnosed with depression. Special questionnaires about the symptoms are often used to help with the diagnosis. Depending on the number, type and severity of symptoms, the depression is considered to be mild, moderate or severe. The treatment options will depend on how severe the depression is.


Distressing experiences like a major loss or chronic stress can contribute to the development of depression. Avoiding certain negative influences or learning to deal with them differently can help lower the risk of depression. That can be particularly important for children and teenagers.

The people in your life also play a big role. Having stable relationships lowers the risk of depression. And getting psychological help or counseling early on can also help to prevent depression. For people at high risk of recurring depression, long-term treatment with medication might be considered for prevention. Some people have regular psychological treatment sessions over a long period of time.


There are various treatment options for depression. The main treatments are psychological treatment (such as cognitive behavioral therapy) and/or medication. Which type of treatment is the most appropriate, where it should take place and how long it lasts will depend on several factors, including how severe the person’s depression is, their personal circumstances, and how their symptoms develop over time. People can talk to a therapist about the advantages and disadvantages of the possible treatments, as well as what they expect from treatment and any fears they might have.

Everyday life

Depression makes it difficult to cope in everyday life. The demands of work, private commitments and even small household chores can become a major effort. Relationships with partners, friends and family often change. Those close to someone with depression usually find it very distressing too. Emotional withdrawal and apathy can lead to arguments and people might become even more withdrawn.

Still: Many who have mental health problems or illnesses turn to their partner, family or friends first. These people are often the first to notice that something is wrong. Their comfort and support is particularly important to those who have depression. But partners, family and friends need help too if the depression is severe. As well as seeking advice from doctors and psychotherapists, they can turn to support groups too.

Active help and support are especially important if there's reason to believe that someone is thinking of killing themselves. It is incredibly important to take any signs seriously and talk to others about it. If that isn't possible in an acute situation, there are various places you can turn to for help. In Germany, these include social-psychiatric services (in German: Sozialpsychiatrische Dienste), crisis support centers and a special crisis helpline (Telefonseelsorge) which is anonymous and available 24 hours a day.

Further information

In Germany, most people with mental health problems or illnesses turn to their family doctor first when looking for professional help and advice. But you can also contact psychological support services, or the private practices of psychiatrists or psychotherapists. In urgent cases such as an acute risk of suicide, you can contact a practice that offers out-of-hours services, or the drop-in center of a psychiatric hospital.


  • Deutsche Gesellschaft für Kinder- und Jugendpsychiatrie, Psychosomatik und Psychotherapie. Behandlung von depressiven Störungen bei Kindern und Jugendlichen. Evidenz- und konsensbasierte Leitlinie (S3). AWMF-Registernr.: 048-023. July 2013.
  • Deutsche Gesellschaft für Psychiatrie und Psychotherapie, Psychosomatik und Nervenheilkunde (DGPPN). S3-Leitlinie und Nationale Versorgungsleitlinie (NVL): Unipolare Depression. AWMF-Registernr.: nvl-005. March 2017.
  • National Institute for Health and Care Excellence (NICE). Depression in adults: recognition and management. October 2009. (NICE Clinical Guidelines; Volume CG90).
  • Robert Koch-Institut (RKI), Statistisches Bundesamt (Destatis). Depressive Erkrankungen. Berlin: RKI; 2010. (Gesundheitsberichterstattung des Bundes; Heft 51).
  • IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

    Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.

    Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK279285