Table 1.
Summary of Human Studies Showing Association of Met Allele and Memory
| Author | Brain Area | Task | Met Carriers Compared to VV | Memory/Cognitive Function | Total Number of Subjects |
|---|---|---|---|---|---|
| Egan and others (2003) | Hippocampus/medial temporal lobe | WMS-R; N-back; fMRI | Lower score; abnormal activation pattern | Episodic memory | 641 |
| Hariri and others (2003) | Hippocampus | Scene recognition fMRI | Reduced activity | Episodic/declarative memory | 64 |
| Pezawas and others (2004) | Hippocampus | Structural MRI | Smaller volume | — | 214 |
| Szeszko and others (2005) | Hippocampus | Structural MRI | Smaller volume | — | 19 schizophrenic 125 healthy volunteers |
| Pezawas and others (2004) | Gray matter in the dorsolateral prefrontal cortex | Structural MRI | Smaller volume | — | 214 |
| Rybakowski and others (2003) | Prefrontal cortex | WCST | Lower score | Prefrontal cognition | 54 |
| Rybakowski, Borkowska, Skibinska, Szczepankiewicz, and others (2006) | Prefrontal cortex | N-back | Lower score schizophrenic patients | Visual working memory | 111 bipolar 129 schizophrenic |
| Rybakowski, Borkowska, Skibinska, and Hauser (2006) | Prefrontal lobe | WCST | Lower score bipolar patients | Working memory | 111 bipolar 129 schizophrenic |
| Miyajima and others (2008) | Hippocampus | Delayed recall; alphabet-coding task | Reduced performance | Memory/cognitive ability | 722 |
| Goldberg and others (2008) | Medial temporal lobe | Depth of encoding and delay of recall | Lower % correct hits | Verbal recognition memory | 48 |
| Schofield and others (2009) | Fronto-hippocampal systems | IntegNeuro | Higher number of errors | Verbal learning and memory | 475 |
| Hippocampal gray matter | |||||
| Hippocampus | |||||
| Dorsolateral PFC | Structural MRI | Smaller volume | |||
| fMRI oddball task | Increased activity | ||||
| fMRI oddball task | Decreased activity | ||||
| Hashimoto and others (2008) | Bilateral hippocampi and right parahippocampal gyrus | WMS-R; fMRI | Decreased activation | Encoding of episodic memory | 58 |
| Beste and others (2011) | — | Partial report | Decreased time of stability | Visual-sensory (iconic) memory | 211 |
| Ho and others (2006) | Medial temporal lobe | Rey Auditory Verbal Learning Test; WMS-R; Rey-Osterrieth Complex Figure Test; WAIS-R; Benton Judgment of Line Orientation | Decreased performance | Verbal memory; visuospatial abilities | 114 healthy volunteers 293 schizophrenic |
WCST = Wisconsin Card Sorting Test; WMS-R = Wechsler Memory Scale–Revised; WAIS-R = Wechsler Adult Intelligence Scale–Revised; PFC = prefrontal cortex; VV = Val/Val; — = not applicable.