Brain Research

Behind the research: How the latest studies may one day prevent delirium

Dr. Bev Orser
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Written by Jennifer Palisoc

Dr. Beverley Orser, is the co-director of research in the department of anesthesia at Sunnybrook Health Sciences Centre, co-founder of the Perioperative Brain Health Centre and chair of the department of anesthesia, University of Toronto.

Dr. Orser’s laboratory has been investigating safe ways of preventing delirium in patients. Her latest study has been published in the journal Anesthesiology.

What is delirium and why is it important?

Delirium is a state of mental confusion that develops acutely. It is serious and common complication that develops in some patients, particularly those that are older and sicker. Delirium can happen after surgery, in intensive care units (ICUs) or in emergency room or other healthcare-related settings. Exposure to anaesthetic drugs and inflammation likely contribute to delirium and potentially to long-term cognitive deficits including memory loss.

It is important for patients and their families to be aware of delirium because it can severely impact a patient’s recovery. The effects of delirium are usually temporary, but memory and other cognitive deficits can last for weeks. These deficits are associated with poor outcomes and even increased mortality.

What are signs and symptoms of delirium?

Signs of delirium include:

  • being inattentive
  • restless and upset
  • forgetfulness
  • confusion
  • hallucinations
  • hostility
  • withdrawal
  • acting differently than normal
  • speech that is unclear

What has your latest research discovered about preventing delirium?

For the past two decades, we have been studying how the brain changes during and after, anesthesia and surgery. We have also been trying to identify strategies to help prevent or treat delirium in patients.

In the past, we assumed that after the anesthetic drugs were eliminated from the patient’s system, the brain would return back to its normal state. But, that’s not what happens in all cases. While the drugs are gone, they can trigger lingering effect that impair brain function. They can trigger certain receptors to be overactive, particularly, in the parts of the brain that deal with memory and problem solving – the hippocampus and cortex.

Research from my laboratory has found, in preclinical studies, that the drug dexmedetomidine can help prevent these post-anesthetic cognitive changes. These changes may be contributing to the delirium that patients experience. Dexmedetomidine is currently being used in the ICU for sedation but should only be administered in highly monitored settings. Dexmedetomidine may prevent delirium by preventing the overactivity of the receptors after anesthesia and surgery. This preclinical work has the potential to make a difference for patients and their families.

What does this mean for patients and their families?

There are several reasons why it is important to understand how dexmedetomidine reduces post-operative delirium.

An understanding of how the drug reduces post-anesthetic cognitive deficits strengthens the rationale for using dexmedetomidine to prevent or treat post-operative delirium.

Also, dexmedetomidine has several serious adverse effects including changes in blood pressure and heart rate. This research will help us to develop new therapies that have fewer adverse effects.

Our results have implications that go well beyond the perioperative period. The receptors we are investigating have also been implicated in several neurologic disorders including stroke, Alzheimer’s disease, depression, and inflammation-induced brain injury. Dexmedetomidine, and related drugs that target similar signaling pathways, may one day help to prevent and treat memory and problem- solving deficits associated with these disorders.

What’s next?

We continue to study how anesthetic drugs and inflammation alter brain function after surgery and anesthesia. We hope to extend the findings from these studies to the discovery of novel treatments for post-operative delirium and other brain disorders.

About the author

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Jennifer Palisoc

Jennifer Palisoc is a Communications Advisor at Sunnybrook.

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