Functional genetic variation in BDNF (brain-derived neurotrophic factor) is posited to impact neural activity in the hippocampus in a manner relevant to schizophrenic pathophysiology. To test this hypothesis, 47 medication-free patients with schizophrenia or schizoaffective disorder and 74 healthy control individuals underwent genotyping for the BDNF Val66Met single-nucleotide polymorphism and [15O]H2O positron emission tomography during rest, sensorimotor (0 bk) and working memory (2 bk) conditions. When compared with their genotype-matched control cohort, only patients carrying the BDNF Met variant showed diminished mean whole-hippocampus perfusion, regardless of scanning condition (bar graphs; Bonferroni-corrected post-hoc tests: P ¼ 0.0004 (rest), P ¼ 0.004 (0 bk), P ¼ 0.02 (2 bk)). Mean voxel-wise resting perfusion maps rendered to hippocampal surfaces are likewise shown for each group with warmer colors (color bar), indicating greater normalized regional cerebral blood flow values. This research was supported by the

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