Sexually dimorphic health disorders have provided scientists with a challenge. Sexual dimorphism means that there are different factors underlying the disorder for each sex. The scientists have a position to ensure that the variations between two genders are apparent when a disease takes place in distinct ways. Autism is a prerequisite to this challenge. While the variations between the sexes in autism are known, the biological and psychological implications of these differences are poorly understood (Mandy et al., 2012). Traditionally, autism was assumed as being related to environmental factors such as relationship with the parents, physical activity and nutrition. This led to scenarios where those close to the child were blamed for the condition. Many times, mothers were blamed for not being close or friendly enough to the child (Ladd-Taylor and Umansky, 1998). This changed when scientists realised that autism was mainly as a result of structural abnormalities within the central nervous system.
Neuropsychologists were placed at the centre of research on autism in the 1980s (Miles et al., 2005). From then, autism became known as a condition that results from the inability of brain cells to process and transmit information. Brain cells are responsible for transmission of a number of stimulus that regulate the functioning of the body. The functioning is key in ensuring that an individual leads a normal life and can perform most of the basic functions without assistance. The roles of stimulus from the brain in coordinating body functions ranges from basic movement of body parts to social behaviour. Among the key areas of the brain whose malfunction leads to autism is corpus callosum. The corpus callosum facilitates communication between various parts of the brain. Amygdala is another key section of the brain connected with autism. It is responsible for emotions and social behaviour. Cerebellum is involved in coordination, balance and motor activity of the body parts (Nelson et al., 2010). Abnormalities in these three parts has been associated with autism. These abnormalities are usually affiliated with poor development of the brain during the early stages of life. Though this poor development can affect a child of either gender, statistics have indicated that male children are more likely to become autistic compared to their female counterparts. The severity of the condition in both genders also vary. Therefore, there is need to determine whether sexual dimorphism in autism results from structural abnormalities of these parts of the brain. Since research has already established the most affected parts, further studies should focus on these parts to determine whether the differences in how the disease affects make and females can be accounted for using brain structure. This research will look use images of the brain obtained through magnetic resonance imaging to compare and contrast these differences. The images will be obtained from four different groups: healthy males, autistic males, healthy females and autistic females. The two healthy groups will form the control groups of the female and male autistic ones. The paper will answer the following research questions: What structural similarities and differences exist between the bilateral anterior insula of male and female individuals suffering from autism? What do the differences between the volumes of the bilateral anterior insula healthy and autistic patients imply about sexual dimorphism of autism?
It is hypothesized that exist significant differences in structural abnormalities between males and females suffering from autism. This research aims at investigating the differences in bilateral anterior insula volume between healthy individuals and those diagnosed with autism. It will also seek to determine sex-by-diagnosis interaction in bilateral anterior insula volume. It will also establish the relationship between sexual dimorphism of autism and the bilateral anterior insula volume in both genders.
Participants and Sampling
This study involved non-probability sampling. The subjects were reached through a special school. The teacher was conducted who linked the researchers to the subjects’ parents for consent. A total of 33 parents gave their consent. The research involved 19 males and 14 females suffering from autism. 22 subjects were white, 7 were African-American while four were of Asian ancestry. The control group was made up of a similar number of participants for each gender. However, the ethnicity varied with 18 whites, 9 African Americans and 6 Asian Americans. The researcher selected individuals with no history of mental or psychological complications to form the control group. The ages of the children selected for this research ranged between five years and sixteen years old. Individuals in the control group were chosen to ensure that their ages match those of the autistic children. The mean age of the boys was 10.9 years while that of the girls was 11.4 years.
After this selection, the participants underwent further assessment for autism. The participants and their parents/guardians were interviewed to determine the time which they started showing symptoms of autism. These interviews were also meant to help the researchers determine the ability of the children to exhibit the right emotions, appreciate or reward those around them or show affection to people or objects such as pets. Out of the 33 autistic respondents, 11 had developed the symptoms after the age of 10, nine developed the symptoms between ages 5 and 10 while the remaining 14 first showed autistic symptoms before attaining the age of 5. The control group was revaluated with the aim of excluding those who were on serious medications or were drug dependent. Drugs are likely to alter the structure of the brain and this will produce in accurate results.
This study used data obtained through magnetic imaging resonance. Both groups were scanned using a 3.0 T Siemens Prisma human MRI scanner that obtained gradient-echo images (echo time= 3.0 ms, flip angle: 10°, repetition time: 2200ms). The scan produced printable images of the bilateral anterior insula of the brain. The technician operating the scanner was instructed to ensure that all the scans be carried out under similar conditions and tuning of the scanner. Each subject spent four minutes on the scan. All the subjects in the experimental group had had an experience with this procedure and they therefore behave normally. Some of the control group respondents had a problem adjusting to the environment in the scanning room but eventually the technician got a way of making them comfortable about the procedure. Analysis of variance was used to determine the existence of sex-by-diagnosis interaction between the male and the female subjects. A color bar was also used to represent F statistics.
Subjects with autism from both genders exhibited reduced volume of the bilateral anterior insular compared to their healthy control group counterparts. The right amygdala was the most affected in both cases when compared to the control groups. There are no clear distinctions between bilateral interior insular volume of both control groups. Both autistic male and females exhibited a similar amygdala volume when compared to the control groups. Therefore, the data on differences between these two is of negligible statistical significance. The sex-by-diagnosis interactions on the right and left sides of the insula were (p = .03, svc) and (p = .003, svc) respectively. These interactions extended to the left sides of the posterior insula for both genders. The Autistic males exhibited a relatively larger bilateral anterior insula volume compared to the corresponding control group. On the other side, autistic females exhibited reduced insula volume compared to the female control group.
Sexual dimorphism in autism is a complex. This complexity is worsened by the fact that keen morphometric analyses of the corpus callosum have identified differences between normal males and females. This research identified no significant differences in this aspect. In a study conducted by Yokota et al. (2005) using three-dimensional mathematical relations on MRIs, there were significant differences between the two genders. The differences between genders in this aspect has evolved and improvement in technology has played a key role in solving the debate within the scientific community. The corpus callosum area has been identified as being relatively larger in most females (Ardekani et al., 2012). Such discoveries have complicated the relationship between a healthy brain and one of a person affected by autism in both genders. This study identified statistically significant differences between males and females in the experimental group. The autistic males had a relatively smaller bilateral anterior insular volume from the MRI images compared to the male control group. The autistic females had a relatively smaller insular volume compared to the corresponding control group. However, the females showed a less statistically significant reduction on the volume of their anterior insular. These results were then compared with the results from the autism behavior checklist. On this checklist, it had emerged that the autistic males tested positive for most of the items. Most of the respondents in the experimental group tested above 75% while most of the females tested between 50 and 75%. These results have an implication on the differences in the effect of brain damage on the behavior of autistic children. In the males, a little damage on the parts of the bilateral anterior insular have a devastating effect on the functioning of their brain. Though this study did not bring out the differences in bilateral anterior insular volumes between the genders, prior studies utilizing more refined technology have shown that females have a larger volume. Despite the fact that the autistic ones had a relatively reduced volume, they did not exhibit very severe autistic tendencies. The major implication of this research is that a similar effect of autism on the bilateral anterior insular is likely to have graver effects on the males than the females. This may be used to account for the differences in the severity of the disease between the genders. Banach et al. (2009) notes that though females are at risk of autism where genetic factors are involved, they tend to be less impaired than their male siblings. Therefore, the damage on the brain of females has a relatively lesser contribution towards the onset of autism.
Ardekani, B. A.; Figarsky, K.; Sidtis, J. J. (2012). “Sexual Dimorphism in the Human Corpus Callosum: An MRI Study Using the OASIS Brain Database”. Cerebral Cortex. 23 (10): 2514–20. doi:10.1093/cercor/bhs253
Banach, R., Thompson, A., Szatmari, P., Goldberg, J., Tuff, L., Zwaigenbaum, L., & Mahoney, W. (2009). Brief report: Relationship between non-verbal IQ and gender in autism. Journal of Autism and Developmental Disorders, 39(1), 188.
Ladd-Taylor, M., & Umansky, L. (1998). ” Bad” Mothers: The Politics of Blame in Twentieth-Century America. NYU Press.
Mandy, W., Chilvers, R., Chowdhury, U., Salter, G., Seigal, A., & Skuse, D. (2012). Sex differences in autism spectrum disorder: evidence from a large sample of children and adolescents. Journal of autism and developmental disorders, 42(7), 1304-1313.
Miles, J. H., Takahashi, T. N., Bagby, S., Sahota, P. K., Vaslow, D. F., Wang, C. H., … & Farmer, J. E. (2005). Essential versus complex autism: definition of fundamental prognostic subtypes. American Journal of Medical Genetics Part A, 135(2), 171-180.
Nelson, S. M., Dosenbach, N. U., Cohen, A. L., Wheeler, M. E., Schlaggar, B. L., & Petersen, S. E. (2010). Role of the anterior insula in task-level control and focal attention. Brain structure and function, 214(5-6), 669-680.
Yokota, Y.; Kawamura, Y.; Kameya, Y. (2005). “Callosal Shapes at the Midsagittal Plane: MRI Differences of Normal Males, Normal Females, and GID”. 2005 IEEE Engineering in Medicine and Biology 27th Annual Conference: 3055–8. doi:10.1109/IEMBS.2005.1617119.
Research Consent Form to be Signed by The Parent/Guardian on Behalf of the Child
Name of the Participant: ……………………………………………………………………….
Date of Birth: …………………………………………
Purpose of Research
This research aims at investigating the differences in bilateral anterior insula volume between healthy individuals and those diagnosed with autism. It will also seek to determine sex-by-diagnosis interaction in bilateral anterior insula volume. It will also establish the relationship between sexual dimorphism of autism and the bilateral anterior insula volume in both genders.
Description of Research
Preliminary tests before the retrieval of data will be conducted to determine the extent level of autism. This will mainly involve the autism behavior checklist. It consists of a questionnaire that measures autistic symptoms in both educational and clinical settings. In the actual research, we will obtain an image of your child’s brain through magnetic resonance imaging. This will help the researcher compare how differences in the structure of the brain manifests in autism.
There is minimal likely physical in the research because the MRI scan will be conducted by a technician. However, the child may develop psychological problems due to the concern that he/she is receiving medical attention. We request that you assist us in helping him/her understand the necessity of this procedure.
The results obtained through the autism behavior checklist can be used by the child’s teachers and other handlers. The checklist will help them in understanding the physical and mental abilities and weaknesses of the child. Therefore, they can devise ways to overcome the challenges and build on the strengths. The MRI scan results can also be used to determine the extent to which the condition has affected the Child’s brain. Unluckily, there are no direct benefits for the control group. The study has tremendous benefits to the society because it will help in understanding how the structural differences of the brain affect children with autism and how specific interventions can be put up for each gender.
We will ensure that any data collected from your child remains confidential. The child’ name will not be mentioned anywhere in the final paper. We will also inform you and seek your consent in case we intent to do anything that is not mentioned in this form.
Considering this explanation, you can choose whether to agree or deny the involvement of your child in this study. Please complete the form if you agree.
I consent that my child…………………………………………………………can take part in this study.
Name of the Parent/Guardian……………………………………………………………
Relationship with the Child (if Guardian) ………………………………………………
Name of the Person Explaining the consent…………………………………………. Signature……………………………. Date………………………………………….
Name of Witness……………………………………………………Signature………………………………Date…………………….