Table 3.
Visual processing
| Study | Age at different assessments (in months) | Total number of participants | Number of EL siblings | Number of siblings with ASD outcome | Number of siblings with TD outcome | Number of siblings with another outcomea | Topic | Assessment method | Diagnostic instruments | Difference EL-ASD vs EL-TD and/or predicts ASD diagnosis | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Estes et al. (2015) US [26] | 6, 12, 24 | 308 | 210 | 31 | 161 | 18 | Visual processing | Mullen Scale of Early Learning (MSEL) | ADOS-G, ADI-R, expert clinical judgment according to DSM-IV-TR | No |
On the Visual Reception scale: at 6 m EL-Autism (autism diagnosis) had a significantly lower score than TL no difference between EL-ASD, EL-TD and TL was found at 12 m EL-ASD showed a lower score than TL at 24 m EL-Autism had a lower score than EL-TD and TL EL-ASD had a lower score than TL |
| Germani et al. (2014) Canada [44] | 24, 36 | 90 | 59 | 14 | 45 | Visual processing | Infant Toddler Sensory Profile (ITSP) | ADOS-G, ADI-R, MSEL, expert clinical judgment according to DSM-IV-TR | No | At 24 m no difference was found between EL-ASD, EL-TD and TL | |
| Kaur et al. (2015) US [43] | 6, 9, 12, 15, 18, 24 | 32 | 16 (2 preterm) | 3 | 8 | 5 | Visual processing | Infants seated in a booster seat. Objects presented: a rattle, a koosh ball, a rigid ball | Ages and Stages Questionnaire-third edition (ASQ-3), Modified Checklist for Autism in Toddlers (M-CHAT), follow-up inquires with parents | No |
EL showed a general trend of excessive visual exploration of objects, irrespective of the novelty of the objects (i.e. excessive looking at the rattle at 6 m and at the koosh ball at 12 m), compared to TL TL but not EL showed increased looking at the koosh ball from 12 to 15 m |
| Landa et al. (2006) US [47] | 6, 14, 24 | 87 | 87 | 24 | 52 | 11 | Visual processing | MSEL | ADOS, expert clinical judgment according to DSM-IV | Yes |
At 14 m EL-ASD showed the same score in visual processing as EL-TD EL-ASD showed a lower increase over time than EL-TD EL-ASD showed the lowest increase over time |
| Landa et al. (2012) US [41] | 6, 14, 18, 24, 30, 36 | 204 | 204 | 52 | 121 | 31 | Visual processing | MSEL | ADOS-G, expert clinical judgment | Yes |
EL-ASD were more likely assigned to the developmental slowing class compared to EL-TD (typical functioning at 6 m followed by attenuation in developmental rate and severe delay in visual processing) EL-Other (BAP) were assigned to normative class (normative visual processing development) |
| Libertus et al. (2014) US [42] | 6, 36 | 129 | 107 | 22 | 57 | 28 | Visual processing | MSEL | ADOS-G, expert clinical judgment according to DSM-IV | No | At 6 m no effect of group on the Visual Reception scale was found |
aAtypical outcome: deficit in general cognition, motor functioning, language delay, Broader Autism Phenotype (BAP, social communication delay)