Comorbidities of Autism in the Area of Developmental Neuroscience
Autism is a developmental condition that occurs in people of all ages and affects people’s perception and interaction with the world (Pemberton & Johnstone, 2018). People with this condition are oftentimes, colloquially-said, living in their own world. They have trouble understanding people’s thoughts, emotions and it is not as easy for them to hold a conversation. However, it should be noted that this is not because of lack of compassion. It was believed that not just any child can develop autism. Before the topic was studied more in-depth, it was believed that this condition only occurs in children subjected to bad parenting or that these children are simply aloof, stupid and lazy (Matson & Williams, 2013). These assumptions, however, are false and far from truth.
Autism can affect any child or even an adult. Pemberton & Johnstone (2018) explain that this condition affects one in 100 people in the UK, however, it is more often found in boys rather than girls. During their early years, autistic children can take longer to reach certain developmental milestones (i.e. talking). They may also use gestures to help them with communication as using facial expressions and holding eye contact may be difficult for them (Pemberton & Johnstone, 2018). Oftentimes, because of the way their minds are, people struggling with autism have to create daily schedules to help them throughout the day. Such schedules can include what time of day to wake up at, when to brush their teeth, eat and so on. Any disruptions in their set routine may cause great stress for them.
Autism cannot be cured and will last throughout a person’s life. However, some people can have high-functioning autism. This is because this condition is thought of as being on a spectrum. Some people can be on the low end, some in the middle and others – on the high end of the spectrum. This is not an official term, however, it is used for people who can tackle every day basic tasks (i.e., eating, getting dressed) (WebMD, 2016). They differ from the average autistic person mainly in a way that they are able to live independently and do not differ greatly from the average person. Even then, however, their difference may present in underdeveloped social skills and voluntary or involuntary repetitive routines that others may consider strange (WebMd, 2016). But what happens when a patient with this condition has to struggle with another illness simultaneously?
Some illnesses develop as a result of autism and can co-exist together. The reason why it is important to study comorbidities in any condition is because they may cause health professionals to misdiagnose the patient. Also, they often mask the main disorder, and hence, only the comorbidities may receive treatment without touching upon the main condition. As far as autism is considered, it is strongly suggested to search for any comorbidities before treating the actual condition (Mpaka et al., 2016). Mpaka et al. (2016) have conducted a study with 405 children aged 1 to 18 and found three comorbidities that co-exist with this condition: with epilepsy scoring 30%, intellectual disability 50-80% and ADHD 20-85%. Other conditions were also noted, but these three disorders stand out because they share a basis that is commonly found in neurology. However, Mpaka et al. (2016) did not share a proper neurological analysis and only stated that the EEG rate was abnormal when their sampled children were studied. The authors do not share which areas of the brain were most affected and how they were different from the norm. However, Mpaka et al. were not the only ones who name epilepsy as one of the comorbidities of autism.
Jeste (2011) confirms that epilepsy is a common comorbidity in autism (30%), along with motor impairment (90%) and sleep disorders (44-83%). However, these comorbidities are associated with the cases where autism is at a severe stage. Jeste (2011) states that sleep disorders and especially insomnia affects 83% of autistic children with epilepsy being present in one-third of them and motor impairment is present in nearly 90% of genetic syndromes associated with autism. Jeste’s study provides the reader with a neurological explanation behind the comorbidities. Specific dysfunctions in the subcortical and cortical areas (specifically, in the mesolimbic cortex and fronto-striatal circuits) lead to motor deficits in autistic children (Jeste, 2011). This may include such things like repetitive behaviours, gait (might improve with age), control of one’s posture and so on. The reason it is important to spot comorbidities associated with motor impairment is because they may be a sign of how early or late a child may reach certain developmental milestones.
There is a neurological explanation for repetitive behaviours as well. They are mostly found in people with low functioning autism (70%), however, high-functioning autists may also display such behaviour (63%) (Jeste, 2011). Most common are those repetitive behaviours that are associated with one’s hand or fingers (i.e., hand flapping, flicking fingers). This is because autistic people with these behaviours were noted to have “aberrant cerebellar as well as fronto-striatal circuitry“ that is specific to this condition, especially when comorbidities are present (Jeste, 2011). However, these are not the only areas that are different in autistic people. It was found that children aged 8 to 12 have an “increased left motor cortex and pre-motor cortical white matter volumes” and also an abnormal basal ganglia shape (Jeste, 2011). In fact, these specific differences often predicted whether children would have problematic motor performances. Those, who would have no issues with this comorbidity often scored low or with no correlation with white matter.
The other comorbidity of sleep disorder, particularly insomnia, is found often in people suffering from autism. However, this comorbidity can range from anything from early awakenings to difficulty maintaining sleep altogether. Because of the nature of this comorbidity, it had to be studied with the help of diaries, observations from parents and to compare the patterns to non-autistic participants. It was found that children with autism who have sleep disorders displayed “shorter total sleep time, greater slow-wave sleep and less REM sleep percentage” (Jeste, 2011). Studies that were done before the current one were also included. Jeste (2011) states that previous studies have found “longer sleep latency, more frequent nocturnal awakenings, fewer stage 2 EEG sleep spindles, and less rapid eye movements during REM sleep”. The need for routine also has to be considered when analysing this comorbidity. Oftentimes, autistic people have to go to sleep at a certain hour, because that is how their daily schedule is planned out. Therefore, there is a possibility that their circadian rhythm is disturbed, because of possible disturbances in the schedule. However, the main reason to suspect sleep disorders is because the “N-Acetylserotonin O-methyltransferase (ASMT) gene, which encodes the final enzyme needed for melatonin synthesis, is less active“ in autistic people (Jeste, 2011). That, in turn, leads to less melatonin being present, which makes it difficult to fall asleep.
Epilepsy is said to come with two peaks and different seizure types. This means that ones at risk of developing epilepsy as a comorbidity are children and adolescents and vice versa, autism can occur as a comorbidity in 46% of children with epilepsy (Jeste, 2011). A study was done with 345 autistic patients in order to figure out a pattern of the seizures. It was found that “44% of paroxysmal abnormalities were focal, 12% generalized and 42% mixed” with “focal abnormalities… localized to temporal regions in 31%, frontal in 18%, occipital in 13% and parietal in 5%” (Jeste, 2011). It was suggested that epilepsy should be treated to prevent autism developing in children. However, there was no support to this suggestion to state that it would have a positive or any effect whatsoever. However, epilepsy does seem to be closely connected to autism as they correlate with neurodevelopmental impairment.
These comorbidities seem to only be natural and expected to be present in people with autism. However, it seems that they are characteristic in the severe type. But because there is little known behind the cause of this condition and with no known cure, there have to be a lot more studies done on this topic. Studying comorbidities and autism in general will help paint a bigger picture and possibly aid with creating effective treatment or prevention to the condition and its comorbidities.
Jeste, S. (2011). The Neurology of Autism Spectrum Disorders. Current Opinion in Neurology, 24(2). Doi: 10.1097/WCO.0b013e3283446450
Matson, J., Williams, L. (2013). Differential Diagnosis and Comorbidity: Distinguishing Autism from Other Mental Health Issues. Neuropsychiatry, 3(2).
Mpaka, D., Okitundu, D., Ndjukendi, A., N’situ, A., Kinsala, S., Mukau, J., Ngoma, V., Kashala-Abotnes, E., Ma-Miezi-Mampunza, S., Vogels, A., Steyaert, J. (2016). Prevalence and Comorbidities of Autism Among Children Referred to the Outpatient Clinics for Neurodevelopmental Disorders. The Pan African Medical Journal, 25(82). Doi: 10.11604/pamj.2016.25.82.4151
Pemberton, B., Johnstone, A. (2018). What is Autism, What are the Signs and Symptoms in Children, What Does Being on the Spectrum Mean and What is High Functioning? The Sun. Retrieved from https://www.thesun.co.uk/fabulous/2798008/autism-symptoms-signs-spectrum-children-high-functioning/
WebMD. (2016). What is High-Functioning Autism? WebMD. Retrieved from https://www.webmd.com/brain/autism/high-functioning-autism