Dissociative amnesia: memory loss linked to trauma and stress

The NHS describes dissociative disorders as a range of conditions that can cause physical and psychological problems. Some are very short-lived, perhaps following a traumatic life event, and resolve on their own over weeks or months, while others last much longer.

In dissociative amnesia, someone has periods where they cannot remember information about themselves or events in their past life. The NHS notes that they may also forget a learned talent or skill. It stresses that these gaps are much more severe than normal forgetfulness and are not the result of another medical condition.

This is different from amnesia caused by a head injury, dementia or intoxication, where the memory problem has a physical or substance-related explanation. In dissociative amnesia, the memory loss is understood as a way the mind copes, which is why assessment includes checking for physical causes first.

The NHS lists general symptoms of dissociative disorders, some of which may be present alongside amnesia. The specific feature of dissociative amnesia is the memory gap itself.

• Periods in which information about yourself or events in your past life cannot be recalled.

• Forgetting a learned talent or skill.

• Finding yourself in a strange place without knowing how you got there; the NHS says the person may have travelled there on purpose or wandered in a confused state.

• Feeling disconnected from yourself and the world around you, or uncertain about who you are.

• Blank episodes lasting minutes, hours or days, and in rare cases months or years.

The causes of dissociative disorders are not well understood, according to South London and Maudsley NHS Foundation Trust. They may be related to a previous traumatic experience, or to a tendency to develop more physical than psychological symptoms when stressed or distressed.

The NHS says someone with a dissociative disorder may have experienced physical, sexual or emotional abuse during childhood, and that some people dissociate after experiencing war, kidnapping or even an invasive medical procedure. Switching off from reality is described as a normal defence mechanism, a form of denial, which becomes a problem when the environment is no longer traumatic but the person still acts and lives as if it is.

The Royal College of Psychiatrists notes in its PTSD information that dissociative amnesia can be a symptom of post-traumatic stress disorder, described as being unable to remember parts of the traumatic event, a common way the brain tries to protect itself. It adds that this can make things harder in the long term.

The NHS lists other conditions that may occur alongside a dissociative disorder, including post-traumatic stress disorder, depression, mood swings, anxiety and panic attacks, self-harm, eating disorders, obsessive compulsive disorder and sleep problems.

A GP is the usual first step if you or someone you know is losing memory for personal information, time or events, particularly after a stressful or traumatic experience. Memory loss with a head injury, confusion, severe headache, new weakness or fits needs urgent assessment through NHS 111, A&E or 999 because a physical cause must be excluded.

The NHS and South London and Maudsley both say that anyone with thoughts of taking their own life should ask someone for help, go to the nearest A&E, contact NHS 111 or make an urgent appointment with a GP.

If you are worried about someone else, SLaM suggests encouraging them to talk about how they feel, listening without judging or offering solutions, and speaking to a member of their care team if they have an existing diagnosis.

The NHS says a GP may examine you and do some tests to check whether another illness might be the cause of your symptoms, and may refer you to a mental health specialist for a full assessment. The specialist should have a good understanding of dissociative disorders.

According to SLaM the assessment may include a physical examination to rule out things like a head injury or drug or alcohol misuse, along with questions about your thoughts, feelings, behaviour and symptoms. The NHS adds that it is important to be honest about symptoms and not to feel ashamed or embarrassed, so you can receive the help and support you need.

Because dissociation can be triggered by reminders of past trauma, assessment is often paced with care and may cover a person's history over more than one appointment.

The NHS says talking therapies such as counselling or psychotherapy are often recommended. The aim is to help you cope with the underlying cause of your symptoms and to learn and practise techniques to manage periods of feeling disconnected.

The NHS says many people with a dissociative disorder make a full recovery with treatment and support. Episodes of dissociation may last hours or days, or longer, and SLaM notes that dissociation can sometimes last years but usually when a person has other dissociative disorders as well.

Understanding what triggers episodes, building a safe routine and working with a therapist who knows about trauma are practical parts of recovery. SLaM says that talking to your partner, family and friends about how past experiences have affected you can help you come to terms with what happened and help them understand how you feel.

For many people, the memory gaps are not permanent, but the pace of recovery varies and cannot be reliably predicted from the sources reviewed here.

On the NHS the route is through the GP to a community mental health team or psychological therapies service. Access to therapists experienced in dissociation and trauma varies by area and waits can be long.

Some people choose a private psychiatrist or psychologist who works with trauma. It helps to check that the clinician is registered with a professional body and has specific experience of dissociative disorders, and to keep the GP informed so that physical causes and risk are monitored.