Amnesia after a traumatic brain injury

Emergency numbers
United States: 911
United Kingdom: 999 or 112
European Union: 112
Elsewhere: your local emergency number

Short answer. After a traumatic brain injury, memories from before or after the accident may be missing, or there may be a confused period during which memories are not recorded normally. These are different situations. Distinguishing them helps describe what happened, while memory difficulties that persist later may require a different assessment.

Important. Amnesia that develops after a recent blow to the head warrants medical assessment in an emergency department, even if the person speaks normally. If they become difficult to wake, increasingly confused, have a seizure, weakness on one side or a worsening headache, call emergency services immediately. Do not repeatedly test their memory to determine the severity yourself.

Three types of difficulty that should be distinguished

Retrograde amnesia affects what happened before the impact: for example, the person remembers leaving home but not the journey before the fall. Anterograde amnesia describes difficulty remembering new information after the event: they hear an explanation of the accident, then ask again a few minutes later what happened.

In a clinical context, post-traumatic amnesia refers to a period after the injury when the person may be disoriented, confused and unable to maintain continuous memory. It is therefore more than a blank space around the moment of impact. The duration and course of this period help professionals characterise the injury; they must not be measured through improvised tests at home.

These concepts sometimes overlap, but they serve a practical purpose: they help explain which events are missing, whether new memories are forming and how the person has behaved since the accident.

Why do those close to the person sometimes notice forgetfulness first?

An injured person may feel they have come round while still being unable to retain recent information. Someone close to them notices that they ask the time five times, keep looking for the same object or cannot follow a conversation started a few minutes earlier. This repetition is not necessarily deliberate.

A common situation is someone asking why they are in hospital. You answer. Ten minutes later, they ask the same question just as sincerely. This behaviour should be reported immediately to healthcare staff, rather than turned into a constant quiz. It may help to note when the person started retaining new information consistently.

For a child, someone with existing cognitive problems or someone unable to explain events clearly, observations from those close to them are even more important. The doctor needs a description of the person’s usual behaviour to assess what has changed.

What should you do about amnesia immediately after a head injury?

The UK’s NICE guidelines list amnesia for events before or after a head injury among the reasons for referral to an emergency department. Even without loss of consciousness or a visible wound, the person needs assessment. Professionals also examine the mechanism of injury, age, other symptoms and medication.

While arranging this care, keep the person safe, stay with them and do not let them drive. Note any vomiting, persistent headache, difficulty walking, unusual drowsiness or change in behaviour. If their condition deteriorates or a serious neurological sign appears, call emergency services immediately. In France, any vomiting after the injury warrants an immediate call to emergency medical services for guidance on care.

A witness can share three very useful observations: the person remembers the meal before the fall, cannot remember the impact, and asks where they are every five minutes. This is more helpful than an unfounded estimate of the number of minutes lost.

Why does a normal CT scan not necessarily explain memory lapses?

The decision to perform a CT scan depends on clinical criteria and risk factors. This examination aims in particular to detect certain acute injuries. Concussion and functional difficulties can exist without any visible abnormality on a conventional CT scan. It would therefore be wrong to conclude that memory is fine solely because imaging is normal, just as it would be wrong to assume a serious injury from an isolated lapse.

Medical assessment and the course of symptoms remain essential. If difficulties persist, professionals may suggest a more detailed cognitive assessment to distinguish attention, learning and memory processes.

What if memory difficulties persist weeks later?

After the acute phase, forgetting an appointment, failing to retain a conversation or losing track of a task does not necessarily involve the same form of amnesia as on the day of the accident. Fatigue, attention problems, disrupted sleep or other cognitive difficulties may contribute. A consultation and, where appropriate, a neuropsychological assessment can help identify what is happening.

For example, someone may remember an instruction given in a quiet setting but forget it if they have to answer three questions at once. This also suggests a difficulty with attention or mental load. Before concluding that their memory is damaged, consider the conditions in which the information was given.

In everyday life, a shared calendar, an alarm, a notebook of reminders or a fixed place for important objects may compensate for some difficulties. These aids do not restore missing memories around the accident, but they can preserve independence. MSKTC stresses choosing strategies suited to the person’s circumstances rather than multiplying exercises with no practical purpose.

How can you discuss forgetfulness without making the person feel they are failing?

Saying that you have agreed to write appointments here is better than saying they never remember anything. Those close to the person can calmly explain information again when needed, without inventing missing memories or expecting the person to describe the impact as a reliable witness. When safety requires it, temporary support can be arranged and then reviewed with the follow-up team.