Beta Blocker Blocks Feelings of Bad Memories

(HealthDay News) -- Imagine being able to decouple bad memories from the fear and anxiety they produce with just a pill.

That's the promise of a new report from Dutch researchers published in the Feb. 15 advance online issue of Nature Neuroscience.

Merel Kindt and colleagues used a beta blocker called propranolol (Inderal) to erase, at least in the short-term, the fear response induced by a laboratory-induced painful memory in humans.

Such findings could one day help individuals suffering from pathological anxiety disorders from the debilitating physiological effects of their fears. Yet many questions remain, experts note, such as how permanent the effect is, and whether it can affect traumatic memories that may be decades old.

"I think it's a very interesting and exciting study," said Jane Taylor, a professor of psychiatry at Yale University, who studies memory reconsolidation in rats. "It will be interesting to know how long-lasting this effect is, and whether it only works on recently consolidated memories."

Mark Bouton, a professor of psychology at the University of Vermont, echoed that sentiment. "This study is a solid step forward in our understanding of how to reduce fear," he said. "The big question is whether this treatment will reduce all forms of relapse, including the return of fear that can occur with the passage of time."

Human memory often is compared to computer storage. Some memories exist in a sort of neurological flash RAM, whereas others are stored for the long term, on the brain's hard disk. The analogy works to a point, but it isn't perfect, as it turns out to be quite difficult to permanently erase files in the brain's memory banks.

"Fear memories can be surprisingly resilient," Bouton explained.

To try to break at least the physiological hold these fears have over individuals, Kindt induced a kind of Pavlovian fear response in 60 undergraduate students at the University of Amsterdam.

The study lasted three days. On the first day, the subjects learned to associate images of spiders with a mild electrical shock. Fear was measured by assessing each individual's startle response -- how much their eyes blinked in response to the stimulus. That fear memory was then consolidated -- written to the hard disk, if you will.

The next day, the memory was recalled, but only after the subjects had been given either placebo or propranolol. The idea, Bouton explained, is that at this point, the memory becomes "open to modification" -- just as a computer file can be changed and then rewritten to the hard disk.

Propranolol had already been shown to impact memory reconsolidation in rodents; the question was, would it have the same effect in people. The answer came on day three, when the subjects were tested again: The physiological response to the fear-inducing cue -- pictures of spiders -- was eliminated in the propranolol group, but not in the placebo group, Kindt found.

"In principle," said Bouton, "this is a step toward finding a clinical treatment for people with pathological fears."

Indeed, the authors noted that their findings "are consistent with those of a recent preliminary study of patients with post-traumatic stress disorder in which post-retrieval propranolol seemed to reduce subsequent physiological responding to traumatic memory."

Yet much remains unknown. For instance, the current research involved only a very short period of time. Though the memory appeared erased on day three, would that still be true a month later? And, it's unclear how effective will propranolol be against longer-term memories, such as traumatic childhood memories that persist into adulthood.

Besides, the experimental memories were not exactly erased in this study, Taylor noted: The propranolol-treated subjects no longer flinched in reaction to the stimulus, yet they knew that they should. That, Taylor suggested, could limit propranolol's clinical utility.

"Being afraid of something doesn't just involve a physiological response," Taylor said, "it's how you think about it and how it affects your behavior."

More information
For more about anxiety disorders, visit the U.S. National Institute of Mental Health.

Stress Disorder Affects 20% of Intensive Care Patients

(HealthDay News) -- About 20 percent of intensive care unit survivors experience symptoms of post-traumatic stress disorder.

That's the conclusion of a study by researchers who reviewed data from 15 previous studies that included 1,745 former ICU patients in the United States and a number of European countries.

The review authors concluded that the trauma of an ICU stay can trigger PTSD symptoms and negatively affect a person's quality of life after they leave the hospital. In studies that used questionnaires to evaluate patients' symptoms, 22 percent of former ICU patients developed PTSD symptoms. In studies that relied on clinician diagnosis, 19 percent of former ICU patients developed PTSD symptoms, the review found.

Nightmares, sleep problems, flashbacks, irritability, anger and feelings of emotional detachment or numbness werere among the symptoms of PTSD.

"Considering that about four million people visit the ICU every year in the United States alone, it's a significant public health issue," review lead author Dr. Dimitry Davydow, an assistant professor in the department of psychiatry and behavioral sciences at the University of Washington School of Medicine in Seattle, said in a Center for the Advancement of Health news release.

Certain factors increased the risk of PTSD after an ICU stay, such as having a prior history of mental health disorders, especially anxiety or depression.

In such patients, "stressful situations can bring about exacerbations of their underlying psychiatric illness. To be treated in an ICU, a person is critically ill and often near death, so it's a very severe stressor. That combination may lead to a later exacerbation of their prior psychiatric disorder," Davydow said.

The review authors also found that patients sedated with benzodiazepine medications (such as Valium and Xanax) were more likely to develop PTSD symptoms, as were those who recalled frightening experiences while they were in the ICU.

"The use of sedatives in the ICU is important, because people need to be sedated if they require mechanical ventilation or other invasive procedures," Davydow said. But he noted that some sedatives, such as benzodiazepines, are more likely to cause disorientation, confusion and psychotic experiences that are so frightening that patients perceive them as an actual traumatic event.

The study was published in the September/October issue of the journal General Hospital Psychiatry.

More information
The U.S. National Institute of Mental Health has more about PTSD.