Lower pattern recognition memory scores in anorexia nervosa.

The hippocampus is an area of the brain that is vital for memory and learning, and it is not understood the extent to which its function is impaired in anorexia nervosa (AN). This paper used the Mnemonic Similarity Task to assess pattern separation, a hippocampus-dependent form of memory, in AN. This task involves showing participants a sequence of objects, who then categorise them as "indoor" or "outdoor" objects. Participants are later shown a sequence of objects, although some of the images are replaced by a similar but slightly different image. The task involves recognising whether an image has previously been seen (pattern recognition) and also whether it is similar to, but distinct, from a previous image (i.e. pattern separation). In this study, individuals with AN showed reduced performance in pattern recognition, when statistically controlling for their age, how the task was delivered and their use of antidepressant medication. However, their performance in pattern separation was intact. This may indicate an imbalance in this hippocampus-dependent form of memory in AN.