"A colleague looked at (the study results) and said, 'Wow, that looks exactly like what happens with a lesion in the hippocampus,'" Janowsky said. "When others have done studies like this on people who have hippocampal damage from early Alzheimer's disease or lesions due to strokes, this is the pattern."
The study examined 30 individuals - 14 men undergoing androgen deprivation treatment for prostate cancer and 16 healthy, age-matched men - from the Portland area. Participants were shown lists of words and, to encode them, were asked to identify whether the words were in capital or lowercase letters, which requires shallow or "perceptual" processing, or whether they represented objects that occurred in nature or were artificially made, which requires deep or "semantic" processing.
Participants were then shown another list containing words they'd just seen as well as new words and were asked whether they'd seen each word before. This test was performed at three time intervals: immediately, after two minutes and after 12 minutes.
Testosterone-deprived men can "immediately get the information in, but then the hippocampus can't consolidate it and send it off for storage," Janowsky said. "When you look at their memory, they're perfectly normal when they're immediately asked to recall something, but they can't hold or save the information as well in order to recall it over a retention interval, over a period of time. They're faster at forgetting."
These results, Bussiere and Janowsky say, point to a negative effect of testosterone deprivation in the hippocampus, which is responsible for storing information from the first few seconds on. Both the prefrontal cortex and hippocampal memory systems commonly show declines with aging and are associated with problems in attention and memory.
"But for long-term memory, the critical structure is the hippocampus. It doesn't mean th
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Contact: Jonathan Modie
modiej@ohsu.edu
503-494-8231
Oregon Health & Science University
25-Oct-2004