Altered mental status (AMS) is a broad term that describes unusual changes in a person’s emotional response, thinking, or behavior.

People tend to be consistent in the way they think and behave. If you’re close to someone or spend a lot of time around a person, you start to see long-term patterns in how they learn, respond, and interact with the world around them.

Your long-term patterns and habits are a part of your “norm.” They’re normal for you, and they’re expected by the people who know you best. When you suddenly start behaving, thinking, or responding in a way that isn’t usual, you may be experiencing an “altered mental status (AMS).”

Read on to learn more about what this state is and why it happens.

AMS is a broad term that describes a change in your baseline consciousness, attention, cognition, or awareness. It’s sometimes referred to as “change in mental status,” “acute confusional state,” or “acute brain failure.”

Doctors use AMS to describe a state of being before an underlying cause is determined. It’s a symptom or clinical observation, not a formal diagnosis.

If you’re experiencing AMS, it means you aren’t reacting, behaving, or thinking like you usually would. You’re not just having a change of heart, either. AMS is an unexplained or significant unexpected change from your norm, and you may not be aware that it’s happened or be able to explain your thoughts and behaviors.

AMS is a symptom, and as a broad term, it encompasses a range of individual experiences. It can describe unusual changes in consciousness, like coma, but it can also describe changes in reality perception, like hallucinations.

If you believe someone is experiencing a mental health crisis, call or contact 988lifeline.org to find mental health services.

AMS can happen for different reasons. Your brain is affected by changes throughout your body, and any alteration to the brain’s function or structure could result in AMS.

Examples of possible causes include:

Brain injury

Injuries to the brain, like from head trauma or a tumor, can damage tissue and disrupt how the brain functions.

Infection

Infections can cause inflammation in the brain, leading to chemical changes that impact thinking and behavior.

Low blood sugar

When your blood sugar is too low (hypoglycemia), your brain doesn’t have enough energy to function. Confusion, slurred speech, and coma are serious AMS presentations of low blood sugar.

Dehydration

Brain cells depend on a delicate balance of fluid and electrolytes. When you’re dehydrated, cell function declines due to changes in blood flow and reduced nerve signaling.

Stroke

A stroke happens when blood flow to the brain is suddenly interrupted and oxygen levels drop too low for brain cells to survive. It can damage any part of the brain, including areas related to thinking and behavior.

Mental health conditions

Underlying mental health conditions, like schizophrenia, can present with changes in thinking and behavior before they are formally diagnosed.

Drug and alcohol use

Some substances, like illegal drugs, medications, and alcohol, can cross into the brain from the bloodstream, where they disrupt the chemical balance and change how the brain functions.

Since AMS is a symptom with many potential causes, it’s difficult to predict who has a higher risk of experiencing it.

Some factors that could increase your chances of AMS include:

  • older age
  • having a family history of a condition that can cause AMS
  • living with any medical condition that could affect brain blood flow, oxygen, chemical signaling, electrolytes, or blood sugar
  • being previously diagnosed with a mental health condition
  • recent major life stress
  • substance use or misuse

AMS is not a formal diagnosis. It’s a clinical observation made by a medical professional when a diagnosis has not yet been determined.

Doctors will decide if you’re experiencing AMS by talking with you, your family members, and other people closest to you. They’ll then assess your level of consciousness and cognition using screening tools like the Glasgow Coma Scale (GCS), Mini-Mental Status Exam (MMSE), or the Confusion Assessment Method (CAM). These tests rate your awareness, attention, memory, language, and reasoning skills.

A medical assessment for AMS will likely include blood tests, urine tests, and imaging, such as CT or MRI of the brain. You may also be given a neurological exam to check your motor function, reflexes, and senses, and to screen for any signs of head trauma.

Treatment for AMS depends on its underlying cause. Some causes of AMS may have simple solutions, such as restoring hydration. Other causes, like a brain tumor, may require surgery or long-term treatment.

If doctors aren’t sure why you’re experiencing AMS yet, they’ll treat you symptomatically, which means they’ll focus on immediate challenges, like regulating vital signs or reducing a high fever.

Safety and comfort are a priority during the diagnostic period, and initial treatment may focus on comfort care until an underlying cause is found.

If no physical causes are identified, your doctor may suggest you speak with a mental health professional to rule out or confirm psychiatric causes.

The outlook in AMS ranges by cause. For some people, AMS can be completely reversible with no lasting side effects. For others, AMS is a symptom of a lifelong or serious condition. It may never completely resolve, or it may worsen over time.

AMS can have serious underlying causes. If left untreated, some may lead to lifelong disability or even loss of life.

Confusion can be a symptom of AMS, but not all people who have a moment of confusion are experiencing an altered mental status. AMS refers to a more significant condition due to an underlying cause.

AMS is not a disease or a formal diagnosis. It’s a term that describes an experience or clinical observation. You can experience AMS without an underlying mental health condition.

AMS is characterized by unexpected, unusual changes in a person’s typical thoughts or behaviors and in their baseline level of awareness.

Altered mental status, or AMS, is a clinical observation made when you aren’t thinking or behaving like you usually would, and often associated with a change in one’s level of awareness or consciousness. Doctors determine AMS by establishing your baseline function and comparing it to your performance on neurological and cognitive tests.

Some presentations of AMS are reversible and won’t cause lasting health complications. Others can be serious, especially if left untreated, and may lead to lifelong disability or even loss of life.