Can autism be diagnosed prenatally?

A question that often concerns future parents and they ask the doctor, who performs a prenatal check to diagnose any abnormalities in their embryo, is whether or not it is possible to diagnose autism prenatally.

Autism is a developmental disorder characterized by reduced social interaction and communication as well as by repeated and stereotyped behavior. Various brain structures are involved in this disorder, in a way not yet sufficiently clarified. This is a serious neuropsychological disorder that is present from the child’s birth and lasts for all his life, preventing or hampering the development of certain psychological skills vital to the psychosocial functioning of the individual. Apart from the child’s life, the family’s life is also directly affected. The incidences of the disease have increased dramatically over the last 40 years (Fombonne 2003). Surveys report incidences of up to 1% in the general population. It appears to be more common in boys than girls, with a frequency of 4:1.

But can the diagnosis of autism be prenatal?

To answer this question, we must look for the causes of this disorder.

The causes are unfortunately still not fully understood. There is no doubt, however, that this is a multifactorial disorder, with genetic or hereditary features as well as a variety of organic causes. Chromosomal abnormalities are only found in a very small percentage of cases (0.3-0.6%)

It seems that a particular gene combination may be predisposed to the manifestation of autism. However, there are risk factors that increase the likelihood of its occurrence. Such factors include parents’ advanced age, exposure to specific drugs or chemicals such as alcohol, maternal metabolic diseases such as diabetes, hypothyroidism, vitamin D deficiency, obesity as well as excessive weight gain during pregnancy

Are there ultrasound indicators for diagnosing autism?

Based on the results of several researches, it was observed that a percentage of children later diagnosed with autism had accelerated brain development during their first years of life. (Redcay & Courchesne, 2005; Courcesne, Campbell & Solso, 2011). Recent studies however do not seem to be consistent with previous results (Zwaigenbaum et al., 2014). Based on this, scientists have tried to study whether such changes can be observed during fetal life in embryos that in future will have autism. So they studied fetal development with ultrasounds in the 2nd and 3rd trimester of pregnancy, on siblings of children with autism (who have an increased risk of having autism) and compared them with embryos without any risk factor (or low-risk embryos for autism). The study of the results did not show any statistically significant results regarding fetal development and the relationship of head perimeter and development between high and low risk embryos.

A retrospective study (Hobbs et al., 2007) which compared the 2nd trimester ultrasound findings, specifically the perimeter of the head of children who had autism, did not show statistically significant differences from children who did not develop this disorder. However, the relationship of unusual diameter to the perimeter of the head appears to be increased in children with autism in relation to the others. Another research (Whitehouse et al., 2011), also retrospective, failed to reveal any significant differences in the perimeter of the head between the two groups. The results are therefore controversial.

Moreover, a prospective research has shown that there is an unusual rate of brain development that may precede autism diagnosis. It appears that high-risk embryos have slightly smaller measurements but a faster rate of growth than low-risk embryos. In this study, however, the sample was quite small, so for more reliable results further research is required with a larger sample. Consequently, at this stage, the prenatal diagnosis of embryos that in the future will show autism is not feasible.

In the future, research may focus on the study of specific regions of the brain that appear to be associated with the manifestation of autism symptoms such as the corpus callosum and the cerebellum. Functional studies with magnetic tomography and three-dimensional ultrasound imaging of the brain allow for more detailed imaging and may, in the future, allow detection and recognition of differences in neuronal development in high-risk embryos for autism manifestation.