Patient information from BMJ

Persistent depressive disorder (long-term depression)

Last published:Aug 25, 2022

Many people have episodes of depression that come on suddenly and can last for months. But if you've got depression that doesn’t go away, or if you keep having bouts of major depression, your doctor may say that you have persistent depressive disorder, or PDD for short.

Treatments for long-term depression can work very well to control the condition. If you have problems with long-term depression you can use our information to talk about the best treatments for you.

What is persistent depressive disorder?

Most people will be affected by a mental health issue at some time, even if only for a short while.

Depression is often like this. A life event, an illness, or a cause that we never really understand can trigger a bout of depression that we need help with.

Doctors call that acute depression. The word 'acute' means something that comes on quickly and doesn’t last a long time.

Persistent depressive disorder (PDD) is different. You may hear it called long-term depression or chronic depression. The word 'chronic' means something that lasts a long time.

PDD is not the same for everyone. There are several types that all come under the heading of PDD. But they all involve symptoms of depression for more days than not, for at least two years.

Types of PDD include:

• A long-lasting low-level depression. This is not major depression, but it’s enough to affect your life so that treatment would help

• A major depression that doesn’t go away

• Recurring episodes of major depression, or

• Low-level depression that sometimes gets worse and becomes major depression. You may have heard this called double depression.

Many people with long-term depression also have problems with anxiety.

About 2 in 100 men and 4 in 100 women have problems with long-term depression. It usually affects adults, but it can also start when someone is a child or teenager.

It’s not always possible to say what causes PDD in an individual person. But we know that causes can include:

• Ongoing stress

• Other long-term medical conditions. For example, health problems that cause constant pain or tiredness can often be linked to depression, and

• Stressful life events, such as the death of a loved one, money problems, or the end of a relationship.

What are the symptoms?

Generally, doctors would say that you have persistent low-level depression if you have at least two symptoms for most of the day on most days. These symptoms include:

• Low self-esteem (feelings of worthlessness)

• Struggling to concentrate

• Finding it hard to make decisions

• Feeling hopeless

• Unusual eating habits. This could mean either a poor appetite or over-eating

• Unusual sleep patterns. This could mean either insomnia (having trouble sleeping) or sleeping too much, and

• Fatigue (extreme tiredness).

Doctors would say that an episode of major depression would involve having many of the symptoms every day for at least two weeks. These symptoms include:

• Depressed mood

• Reduced interest in your usual activities

• Sleeping too much or not enough

• Over- or under-eating

• Agitation

• Slow thinking or slow physical movements

• Fatigue or low energy

• Feelings of worthlessness or guilt

• Difficulty concentrating, and

• Suicidal thoughts.

There are several physical conditions that can cause some of the symptoms of depression, or that can make them worse. So your doctor may suggest some tests to rule them out. These would usually be blood tests.

For example, they may want to check for:

• Any vitamin deficiencies

• Thyroid problems

• Problems with your liver, and

• Problems with your blood: for example, anaemia.

What treatments are available?

The treatments that can help with long-term depression are broadly the same as those for shorter-term spells of depression: namely antidepressant medicines, psychotherapy ('talking treatments'), or a combination of both.

The difference is that people with longer-term depression tend to need more treatment. This usually means:

• A longer treatment period

• More sessions of psychotherapy, and

• Higher doses of medicine.

There is some evidence that medicines may work better than psychotherapy for PDD. It’s also possible that a combination of treatments may work better than just one of them.

Antidepressant medicines

There are many different antidepressants, and you and your doctor can discuss which one may be right for you.

These medicines all take several weeks, and sometimes longer, before they start to work properly. So it may take a while before you feel better.

All antidepressants can cause side effects in some people, especially when you first start taking them. These can include things such as stomach problems, agitation, and sexual problems. Your doctor should discuss these with you before you start treatment.

If you find that your medicine causes side effects that don’t go away, talk to your doctor. You may be able to try a different medicine or a lower dose.

Psychotherapy (talking treatments)

Several talking treatments have been found to be useful for PDD.

Cognitive behaviour therapy (CBT) involves your therapist helping you change the way you think and feel about things that make you unhappy. For example, you may:

• Break down your worries or problems into smaller chunks to deal with them more easily, and

• Look at whether your reactions to problems are helpful or realistic, and at how you may react more usefully.

Interpersonal therapy (IPT) is used to help people whose depression is probably linked to problems with relationships. The aim is to improve relationships with people that are causing you to be depressed.

For example, it may help you if you have been through the end of a marriage or relationship, or if you are struggling with relationships with friends or family members.

Other things that may help

Many people try non-medical treatments for long-term depression, including taking regular exercise, eating a more healthy diet, yoga, and acupuncture.

There is some evidence that these things can be helpful, especially exercise.

Treatment during pregnancy

Not all antidepressants are considered safe to take during pregnancy. For example, some can lead to problems for the baby for several hours or days after they are born.

But stopping treatment during pregnancy could also affect you and your baby.

So, if you are planning on becoming pregnant, talk to your doctor about your treatment options. For example, you may want to consider changing your medicine to one that is considered safe.

If that isn’t possible, you and your doctor should discuss what’s best for you and your baby. There may not be easy answers. But you can at least prepare yourself as much as possible.

Treatment in children and teenagers

PDD can affect children and young people. But most antidepressant medicines are not usually recommended, as they can cause suicidal thoughts in younger people.

Depending on where you live, your child may be able to be given antidepressants, but they will need to be closely monitored for signs of their symptoms getting worse.

What to expect in the future

Many people’s symptoms go away after a period of treatment. But it takes longer for treatment to work in people with PDD compared to those with shorter-term bouts of depression.

PDD is also a long-term condition, so symptoms can sometimes return. But if treatment helped a lot the first time, it is likely to do so again.

The outlook is less good for people whose symptoms only partly improve with treatment.

Long-term treatment with antidepressants can cause symptoms that take longer to appear, such as weight gain and sexual problems. Your doctor should discuss these with you.

You may not need to have treatment for the amount of time it takes for long-term symptoms to appear. But it’s useful to be as prepared as you can.