Table 2.
Summary of studies that investigated both monoamine PET and cognitive functions in patients with schizophrenia and/or healthy subjects.
| Study | Year | Subjects | Cognitive tasks | PET probe | Findings |
|---|---|---|---|---|---|
| Okubo et al. (20) | 1997 | 17 with Sch and 18 HV | WCST | [11C]SCH23390 | Reduced prefrontal D1RA was associated with poor WCST performance |
| Abi-Dargham et al. (21) | 2002 | 16 with Sch and 16 HV | N-back | [11C]NNC112 | Increased prefrontal D1RA was associated with poor working memory |
| Takahashi et al. (22) | 2008 | 23 HV | WCST, ROCFT, RAVLT | [11C]SCH23390 | An inverted U-shaped relationship between prefrontal D1RA and WCST performance |
| Hirvonen et al. (27) | 2005 | 11 unaffected co-twins with Sch and 7 twin HV | WMS-R, CVLT | [11C]raclopride | Higher D2RA in the caudate was associated with a poor performance on tasks related to schizophrenia vulnerability |
| Cervenka et al. (29) | 2008 | 16 HV | Pair associative learning, delayed pattern recognition memory, word recognition, WAIS-R, category fluency | [11C]raclopride | D2RA in the limbic striatum was related to episodic memory, D2RA in the associative and sensorimotor striatum showed associations with non-episodic tasks |
| Vyas et al. (35) | 2017 | 25 with Sch and 19 HV | WCST, CVLT | [18F]fallypride | In individuals with Sch, D2RA was negatively correlated with WCST and CVLT performance whereas positive correlation was observed in HV |
| Takahashi et al. (36) | 2007 | 25 HV | RAVLT, ROCFT, WCST | [11C]FLB457 | Hippocampal D2RA was positively correlated with memory and also associated with frontal lobe functions |
| Yoder et al. (38) | 2004 | 10 with Sch (most were medicated) | PANSS | [11C]CFT | Striatal DAT availability was inversely correlated with scores on the cognitive subscale of PANSS |
| Velnaleken et al. (48) | 2007 | 11 HV | CPT, Stroop, TMT, WCST | [18F]DOPA | Positive correlations between DA synthesis capacity in the caudate nucleus, putamen, and midbrain with performance on TMT-B, CPT, and Stroop test |
| Meyer-Lindenberg et al. (41) | 2002 | 6 with Sch and 6 HV | WCST | [18F]DOPA | Decreased PFC activation measured with fMRI predicted exaggerated striatal DA synthesis capacity |
| McGowan et al. (49) | 2004 | 16 medicated individuals with Sch and 12 HV | Stroop, VF, SDMT | [18F]DOPA | Negative correlations between Stroop interference scores and DA synthesis capacity in the ACC in both individuals with Sch and HV |
| Howes et al. (43) | 2009 | 24 prodromal individuals with Sch, 6 with Sch, and 12 HV | VF | [18F]DOPA | Within the prodromal Sch group, performance on the semantic VF task was negatively correlated with striatal DA synthesis capacity |
| Yasuno et al. (58) | 2003 | 16 HV | WMS-R | [11C]WAY100635 | Negative correlation between explicit memory function and 5-HT1ARA in hippocampus |
| Borg et al. (59) | 2006 | 24 HV | Claeson–Dahl Learning and Memory Test, CPT, spatial working memory test, ROCFT, controlled oral assessment, WCST | [11C]WAY100635 | No correlation between performance on any of the cognitive tests and 5-HT1ARA in the raphe, hippocampus, and neocortex |
| Penttila et al. (60) | 2016 | 24 HV | WCST, WMS-R | [11C]WAY100635 | Global 5-HT1ARA was positively correlated with verbal memory |
| Rasmussen et al. (61) | 2010 | 30 with Sch and 30 HV | Spatial working memory, Stockings of Cambridge, Intra-Extradimensional set-shifting, rapid visual information processing | [18F]altanserin | No correlation between neurocognitive measures and 5-HT2ARA in any region |
| Madsen et al. (63) | 2011 | 32 HV | Stroop, TMT, RAVLT, ROCFT, Intelligenz-Struktur-Test 2000 R | [11C]DASB | Positive associations between 5-HTT availability and Stroop test performance and logical reasoning. No association between 5-HTT availability and memory |
Sch, schizophrenia; HV, healthy volunteer; RA, receptor availability; WCST, Wisconsin Card Sorting Test; ROCFT, Rey-Osterrieth's Complex Figure Test; RAVLT, Rey's Auditory Verbal Learning Test; WMS-R, Wechsler Memory Scale-Revised; CVLT, California Verbal Learning Test; WAIS-R, Wechsler Adult Intelligent Scale-Revised; DLPFC, dorsolateral prefrontal cortex; PANSS, Positive and Negative Syndrome Scale; DAT, dopamine transporter; CPT, Continuous Performance Test; TMT, Trail Making Test; fMRI, functional magnetic resonance imaging; VF, verbal fluency; SDMT, Symbol-Digit Modality Test; ACC, anterior cingulate cortex; 5-HT1A, 5-hydroxytryptamine 1A; 5-HT2A, 5-hydroxytryptamine 2A; 5-HTT, 5-hydroxytryptamine transporter.