Pre-Existing Differences of Mothers of Children with Autism Spectrum Disorder and/or Intellectual Disability: A Review

Background:  

Few common traits separate the mothers of children with autism spectrum disorder (autism) and intellectual disability (ID) from mothers in the general population.

Objectives:  

• To review research on the pre-existing characteristics which differentiate mothers of children with autism and/or ID of unknown cause from each other and from mothers of children without these disabilities
• To provide a source for research into the determinants of autism and/or ID, including the role of genetic and modifiable risk factors. 

Methods:  

The papers considered for this review resulted from a search of the Medline, Web of Knowledge, Scopus and Google scholar databases. Combinations of the search terms associated with autism and ID, the hypothesised aetiologies of autism and ID and terms associated with traits of mothers of children with autism and/or ID were used. Examples from each of the three groups are ‘autis*, pervasive development disorder* and intellectual disability’, immigra*, migra*, ethnic*, immun*’ and ‘traits, characteristics, mothers, children’.

A paper was included in the review if:

• It was published in a peer-reviewed journal between 1990 and 2012 inclusive;
• It was a full text article  in English;
• It described new research;
• It compared a characteristic of parents or mothers of children with ASD and/or ID with parents or mothers of children without disability or with a population norm;
• It assessed characteristics that were pre-existing and not likely to be a result of caring for a child with ASD and/or ID; and
• It used methods of ascertainment and measurement of the characteristic(s) of interest that were assessed as unlikely to lead to bias.

Results:  

Overall, autism was correlated positively with socio-economic status (SES), education and age. By contrast, ID had a negative correlation with each of these variables. A reversal was also apparent with parity where lower parity was associated with the autism group and higher with the ID group. More complex associations were found with immigrant status and ethnicity.  With the former, excluding Californian population studies, the children of immigrant mothers consistently were associated with increased rates of autism (particularly autism with ID) and lower rates of Mild or moderate  ID (mild ID).  A reverse scenario was found in California with a higher proportion of mild ID and a lower proportion of autism in the children of immigrant mothers.  With ethnicity and with the exception of Asian mothers, there are lower rates of autism and increased rates of ID in the mothers of ethnic minority groups. Asian mothers exhibited an opposite trend.  Further, compared to the ID group, many more traits were associated with the mothers of children with autism in the three areas related to immunology, mental health, pregnancy/childbirth and behavioural traits. Possible explanations for these findings are discussed.

Conclusions:  

Further research in these areas may yield more understanding of the genetic and aetiological aspects of autism and ID. In turn, primary and secondary prevention strategies may be refined and/or developed.