Researchers find protein that might reinforce people's fears
From post-traumatic stress disorder to fear of heights, millions of Americans suffer from what scientists call contextual fear -- an emotional response tied to a specific life experience. A war veteran, for example, might hear a loud noise and duck for cover, recalling explosions on the battlefield. Now researchers at MIT have identified a protein in the brain they think prevents people from releasing these troubling memories. The discovery, based on experiments in mice, may point the way toward treatments that could help soldiers and others purge their scary thoughts more easily. Andre Fischer and colleagues placed mice in a Plexiglas box and applied electric shocks to their feet. They then allowed the traumatized mice to reenter the box several times without shocking them, mimicking traditional psychotherapy for contextual fear. Mice that received the inhibitor of the protein Cdk5 only needed one safe trip to the box to forget their fear, while those that got a placebo had to return seven times before they stopped freezing in terror. "We know quite a lot about what happens during acquisition of memories or fear," said Fischer. "But what happens in forgetting, this is a blank basically in the textbooks. This opens up a new therapeutic avenue for treating emotional disorders."
BOTTOM LINE: If proven safe, drugs that inhibit the protein Cdk5 -- already in development to treat Alzheimer's disease and cancer -- could boost the effectiveness of therapy for post-traumatic stress disorder and other anxiety disorders.
CAUTIONS: Cdk5 also helps the brain learn, so stifling it could create unintended side effects.
WHAT'S NEXT: Researchers want to perform more experiments in mice to figure out how Cdk5 works and whether inhibitors of the protein can safely be taken for short periods of time.
WHERE TO FIND IT: Nature Neuroscience advance online, July 15
FELICIA MELLO
AGING Do our funny bones thin as we age?
A new study points to a grim reality: Some of us might find it a bit harder to understand jokes in our golden years. Processing a joke takes abstract reasoning, short-term memory, and cognitive flexibility -- all of which naturally decline as we age. Wingyun Mak and Brian Carpenter , both of Washington University, studied the responses of about 40 undergraduates and 40 people over the age of 65 to various standard tests of humor comprehension. In one, participants were asked to select the logical and funny punch line to a joke from the four possible choices. Results showed that older adults made more errors in choosing the correct, humorous answer. However, since understanding even a simple joke requires a series of tricky tasks for the brain, it still remains unclear exactly which mental task becomes harder to perform as we age.
BOTTOM LINE: Since higher order brain functions naturally decline as we age, understanding humor might be more difficult in our later years.
CAUTIONS: This study only gets at one aspect of humor comprehension. There are many other factors involved in understanding a joke, including prior life experiences, wisdom, and personality. Including these factors in a future study might make it easier to discern between the various contributors to humor comprehension.
WHAT'S NEXT: The research group says that they hope to use the study's results to help design programs and activities for older adults with Alzheimer's disease at adult day care centers.
WHERE TO FIND IT: Journal of the International Neuropsychological Society, July
SUSHRUT JANGI 
