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. 2018 Oct 24;9:504. doi: 10.3389/fpsyt.2018.00504

Table 3.

Characteristics of studies that were not included in the meta-analyses.

Study Diagnosis and number of participants Age, years mean (SD) Gender male/female Summary of main findings
SCZ (n) ASD (n) SCZ ASD SCZ ASD
Chen et al. 2017 (42) Schizophrenia
(35)		 Autism spectrum disorders (22) 15.6
(1.8)		 13.1
(3.1)		 20/15 15/7

  • fMRI study.

  • Shared atypical brain connections were mostly found in the SN and DMN. In ASD, the distinct atypical connectivity was mainly intra-SN connections, while in SCZ it was mainly inter-DMN-SN connections.

  • Shared atypical DMN and SN connections in ASD were significantly related to social deficits; no significant relationship between the connections and the PANSS scores was observed in the SCZ group.
Ciaramidaro et al. 2015 (43) Paranoid schizophrenia
(18)		 Autism (23) 14-32
(min-max)		 13-33
(min-max)		 18/4 23/2

  • fMRI study.

  • ASD group committed more errors than SCZ group in a ToM task, while the latter showed higher reaction times.

  • Increased activation for physical information processing in SCZ, and decreased activation for intentional information processing in ASD.

  • Increased connectivity patterns between the right PSTS and VMPFC in SCZ but decreased in ASD.
Corbera et al. 2017 (44) (abstract) Schizophrenia
(49)		 Autism spectrum disorders
(31)		 NA NA NA NA

  • Greater deficits in empathy for emotional pain in ASD vs. NTC than SCZ vs. NTC.

  • Deficits in perspective taking and personal distress were present in both SCZ and ASD, while deficits on empathic concern and overall empathy were present in ASD only.
Eack et al. 2017 (45) Schizophrenia
(36)		 Autism spectrum disorders
(36)		 26.25
(6.83)		 23.91
(6.05)		 22/14 30/3

  • fMRI study.

  • SCZ performed significantly better than ASD in simple perspective taking trials while both groups performed similarly but significantly worse than NTC in complex trials.

  • SCZ with significantly greater VMPFC and left TPJ activity than ASD. Dense connections between MPF circuit and TPJ in ASD, while only connections between DL and VMPFC in SCZ. Increased bilateral orbitofrontal connectivity in ASD compared to SCZ.
Hirata et al. 2018 (46) Schizophrenia
(15)		 Autism spectrum disorders
(13)		 36
(29-47)* 		30
(23.3-38.5)* 		12/3 12/1

  • fNIRS study.

  • No difference between ASD and SCZ in a facial emotion recognition task.

  • Left frontotemporal area dysfunction during non-social and social cognition tasks in ASD, which was associated with ‘exaggerated attention’. Frontopolar area dysfunction for non-social cognition task in SCZ, which was associated with severity of symptoms.
Katz et al. 2016 (47) Schizophrenia
(24)		 High functioning autism
(23)		 31.21 (8.21) 26.65 (6.51) All Male All Male

  • Whole-brain tractography and VBM study.

  • SCZ and HFA shared common long-range white matter deficits but opposite gray matter abnormalities (decreased volumes in SCZ and increased volumes in ASD).
Le Gall et al. 2012 (48) (abstract) Early-onset schizophrenia
(24)		 High functioning autism
(14);
Asperger's syndrome
(18)		 13.4
(0.57)		 HFA:
12.3
(0.74) AS:
12.3
(0.65)		 NA NA

  • No difference in attribution of intentions ability was observed between SCZ, HFA and AS.

  • HFA showed increased difficulty in understanding figurative language compared to SCZ and AS.

  • HFA/AS had more severe pragmatic impairments than SCZ, as evaluated by the Children's Communication Checklist.
Mitelman et al. 2017 (49) Schizophrenia
(49)		 Autism spectrum disorders
(20)		 42.7
(12.3)		 28.4
(6.5)		 42/7 17/3

  • MRI morphometric study.

  • Participants with SCZ showed a pattern of decreased gray matter and increased white matter volumes compared to participants with ASD, particularly in motor-premotor and anterior frontal cortex, anterior cingulate, fusiform, superior and middle temporal gyri.
Ozguven et al. 2007 (50) (abstract) Schizophrenia
(20)		 Asperger's syndrome
(16)		 Range
18-37		 Range
18-37		 All Male All Male

  • ToM was more impaired in participants with AS compared to those with SCZ.

  • Second-order ToM performance was correlated with negative but not paranoid symptoms in SCZ.
Ozguven et al. 2010 (51) Schizophrenia
(20)		 Asperger's syndrome
(14)		 27.4
(4.75)		 24.4
(7.1)		 All Male All Male

  • Participants with AS performed significantly worse than SCZ in first-order ToM items, while both groups performed significantly worse than NTC in second-order ToM items.

  • In ASD there was a positive correlation between first order ToM and verbal comprehension, while in SCZ a similar correlation was found with second-order ToM, in addition to a negative correlation of this latter measure with negative symptom scores.
Parellada et al. 2017 (52) Early-onset first episode psychosis
(29)		 Autism spectrum disorders
(30)		 14.1
(0.98)		 13.3
(1.99)		 18/11 28/2

  • Region-of-interest and VBM study.

  • Gray matter volume reductions in the right anterior insula and bilateral posterior insula were present both in ASD and FEP.

  • Regional insular volume deficits were associated with severity of symptoms (social communication and insight deficits) in both ASD and FEP.
Pilowsky et al. 2000 (53) Childhood-onset schizophrenia
(12)		 High functioning autism
(12)		 12.2
(1.7)		 13.0
(3.9)		 9/3 11/1

  • No differences between groups in fact and value belief tasks and a false belief task.

  • Individuals with SCZ performed significantly better than those with HFA in a deception task.

  • In HFA, ToM ability was correlated with verbal ability.
Pinkham et al. 2008 (54) Paranoid and non-paranoid schizophrenia/ schizoaffective disorder
(12 P, 12 NP)		 High functioning autism spectrum disorders
(12)		 P: 26.42 (5.25)
NP: 28.0 (3.93)		 24.08 (5.71) All Male All Male

  • fMRI study.

  • No significant differences were found between the groups in a trustworthiness task except for a better performance of non-paranoid vs. paranoid schizophrenia patients.

  • P-SCZ ans ASD with reduced left VLPFC activation compared to NP-SCZ during the trustworthiness task.
Pinkham et al. 2012 (55) Paranoid and non-paranoid schizophrenia/ schizoaffective disorder
(24 P, 30 NP)		 Autism spectrum disorders
(18)		 P: 27.33 (5.96) NP: 29.87 (7.18) 24.56 (6.0) P: 21/3 NP: 25/5 17/1

  • Overall similar level of paranoia in SCZ and ASD groups.

  • Paranoia in SCZ associated with victimization, suspicion, and threat of harm (suggesting externalizing bias), while in ASD it was associated with social cynicism (suggesting increased impairment in understanding social cues and rules of social interaction).
Pomarol-Clotet et al. 2005 (56) (abstract) Schizophrenia
(33)		 Asperger's syndrome
(24)		 NA NA NA NA

  • No difference in performance in ToM tasks between groups.

  • Executive function and memory impairments only present in the SCZ group.
Serrano et al. 2014 (57) (abstract) First episode psychosis patients
(29)		 Autism spectrum disorders
(30)		 13.33 (1.99) 13.08 (2.43) NA NA

  • VBM study.

  • FEP patients had smaller right hemisphere cingulate isthmus volume and cortical thickness than patients with ASD.
Stanfield et al. 2017a (58) Schizotypal personality disorder
(21)		 Autism spectrum disorders
(28)		 37.1
(9.2)		 39.5
(11.6)		 14/7 22/6

  • fMRI study.

  • No significant differences in an emotion recognition task (Ekman 60) and Social Judgements task between SCZ and SPD.

  • SPD group showed significantly greater activation compared to ASD group when making social judgements compared to gender judgements in the amygdala and 3 clusters: right posterior cerebellum, extending into the fusiform and inferior temporal gyri; left posterior cerebellum; and left intraparietal sulcus extending through the medial portions of the temporal gyri into the fusiform gyrus.
Van Lancker et al. 1989 (59) Schizophrenia
(19)		 Autism
(28)		 9.6
(2.1)		 Younger: 6.9
(1.2) Older: 11.3
(3.1)		 NA NA

  • SCZ group performed significantly better on an auditory emotion recognition task compared to the ASD groups (both younger and older participants).

AS, Asperger syndrome; ASD, Autism Spectrum Disorders; DMN, Default Mode Network; ER, emotion recognition; FEP, First Episode Psychosis; fMRI, functional Magnetic Ressonance Imaging; fNIRS, functional near-infrared spectroscopy; HFA, High Functioning Autism; MRI, Magnetic Ressonance Imaging; NA, not available; NP, Non-paranoid; NTC, neurotypical controls; P, paranoid; PANSS, Positive and Negative Syndrome Scale; PSTS, posterior superior temporal sulcus; SD, Standard deviation; SPD, Schizotypal Personality Disorder; SN, Salience Network; SCZ, Schizophrenia; ToM, theory of mind; VBM, voxel based morphometry; VLPFC, ventrolateral prefrontral cortex; VMPFC, ventromedial prefrontal cortex.

*

Results presented as medians and interquartile ranges.

a

This study used a sample of subjects with Schizotypal Personality Disorder.