The effect of G72 genotype on neural correlates of memory encoding and retrieval.

Polymorphisms in the G72 (also named d-amino acid oxidase activator, DAOA) gene increase the vulnerability for schizophrenia and affective psychosis. Three recent genetic neuroimaging studies showed that variation in G72 influences the brain activity in the medial temporal lobe (MTL), supporting the hypothesis that G72 might play a modulatory role on brain activity in MTL structures. In the present study we therefore investigated the effect of G72 on the neural correlates of long-term memory encoding and retrieval in a large sample of healthy subjects (n=83) using functional magnetic resonance imaging. A face encoding and a face retrieval memory task were chosen because on the one hand they specifically activate MTL structures and on the other hand they tap into memory processes that are compromised in patients with schizophrenia and affective disorder. Despite a strong a-priori hypothesis of genotype group activation differences in the MTL along with a large sample size we did neither find an effect of G72 genotype status on brain activity in the MTL nor in any other brain regions. The present data therefore do not support the view of a general modulatory role of G72 on MTL brain activity, at least not in the domain of long-term memory encoding and retrieval. Our results highlight the importance of replication studies in genetic neuroimaging.