Research Review: A systematic review and meta-analysis of sex differences in narrow constructs of restricted and repetitive behaviours and interests in autistic children, adolescents, and adults

Take a Closer Look: Considerations for Autism Spectrum Disorder Assessment in Female Children and Adolescents

Assessment for autism spectrum disorder (ASD) in the pediatric female population entails unique diagnostic complexities. Females are often misdiagnosed, undiagnosed, or receive an ASD diagnosis at a later age than males. Male bias in ASD, masking behaviors, cultural norms, and overlapping neurodevelopmental comorbidities (such as attention deficit/hyperactivity disorder and intellectual disability) contribute to this phenomenon. The authors present two clinical cases evaluated in an interdisciplinary developmental behavioral pediatrics (DBP) team to highlight these considerations. Cases describe adolescent and school aged females with medical complexity who did not initially appear to have ASD symptoms but later were diagnosed with ASD. Patient anonymity is preserved. Best practice recommendations are discussed. Shared decision making, intentional history taking, thorough observation of behavior and restrictive/repetitive/sensory interests in multiple settings, and attention to social communication in the context of cognitive capacity are essential for ASD assessment in pediatric females.

Protocol for a systematic review evaluating psychometric properties and gender-related measurement (non)invariance of self-report assessment tools for autism in adults

BACKGROUND

Given the recent evidence on gender differences in the presentation of autism, there is an increasing concern that current tools for autism do not adequately capture traits more often found in women. If tools for autism measure autistic traits differently based on gender alone, their validity may be compromised as they may not be measuring the same construct across genders. Measurement invariance investigations of autism measures can help assess the validity of autism constructs for different genders. The aim of this systematic review is to identify and critically appraise the psychometric properties of all self-report tools for autism in adults that meet two criteria: (a) they have been published since or included in the NICE (2014) recommendations, and (b) they have undergone gender-related measurement invariance investigations as part of their validation process.

METHODS

A search of electronic databases will be conducted from 2014 until the present using MEDLINE, Embase, and PsycINFO using predefined search terms to identify eligible studies. The search for grey literature will include sources such as OpenGrey, APA PsycEXTRA, and Scopus. Two reviewers will independently screen titles, abstracts, and full texts for eligibility. The references of included studies will be searched for additional records. The methodological quality of the studies will be evaluated using the COSMIN Risk of Bias checklist, while psychometric quality of findings will be assessed based on criteria for good measurement properties and ConPsy checklist. The quality of the total body of evidence will be appraised using the approach outlined in the modified GRADE guidelines.

DISCUSSION

This systematic review will be among the first to assess the psychometric properties and gender-related measurement invariance of self-reported measures for autism in adults that were published since (or included in) NICE (2014) guidelines. The review will provide recommendations for the most suitable tool to assess for autism without gender bias. If no such measure is found, it will identify existing tools with promising psychometric properties that require further testing, or suggest developing a new measure.

SYSTEMATIC REVIEW REGISTRATION

The protocol has been registered at the International Prospective Register of Systematic Reviews (PROSPERO). The registration number is CRD42023429350.

Are the diagnostic rates of autistic females increasing? An examination of state-wide trends

BACKGROUND

Autism has been considered a 'male-dominant' condition. However, recent research suggests that autistic females are underdiagnosed, misdiagnosed, and later diagnosed. Females may also have different and more nuanced behavioral profiles. To examine diagnosis rates of females, we used 20 years of state-wide data to characterize historical trends in the diagnosis of autism in females to determine whether the proportion of females diagnosed with autism has changed over time.

METHODS

Data were drawn from 10,247 participants (males = 8,319, females = 1928) who received an autism diagnosis between 2000 and 2021 from state-wide autism centers associated with the University of North Carolina TEACCH Autism Program.

RESULTS

The rates of females diagnosed with autism increased at a greater rate compared with males. Age of diagnosis remained consistently higher for females. Late diagnosis (defined as 13+) increased over time across both males and females, however, was more commonly associated with females, particularly those with co-occurring intellectual disability.

CONCLUSIONS

Our results indicate that the proportion of females diagnosed with autism has increased steadily over a 20-year period, which likely reflects greater societal knowledge of how autism may manifest differentially in females.

Sex differences in social brain neural responses in autism: temporal profiles of configural face-processing within data-driven time windows

Face-processing timing differences may underlie visual social attention differences between autistic and non-autistic people, and males and females. This study investigates the timing of the effects of neurotype and sex on face-processing, and their dependence on age. We analysed EEG data during upright and inverted photographs of faces from 492 participants from the Longitudinal European Autism Project (141 neurotypical males, 76 neurotypical females, 202 autistic males, 73 autistic females; age 6-30 years). We detected timings of sex/diagnosis effects on event-related potential amplitudes at the posterior-temporal channel P8 with Bootstrapped Cluster-based Permutation Analysis and conducted Growth Curve Analysis (GCA) to investigate the timecourse and dependence on age of neural signals. The periods of influence of neurotype and sex overlapped but differed in onset (respectively, 260 and 310 ms post-stimulus), with sex effects lasting longer. GCA revealed a smaller and later amplitude peak in autistic female children compared to non-autistic female children; this difference decreased in adolescence and was not significant in adulthood. No age-dependent neurotype difference was significant in males. These findings indicate that sex and neurotype influence longer latency face processing and implicates cognitive rather than perceptual processing. Sex may have more overarching effects than neurotype on configural face processing.

Differently different?: A commentary on the emerging social cognitive neuroscience of female autism

Autism is a neurodevelopmental condition, behaviourally identified, which is generally characterised by social communication differences, and restrictive and repetitive patterns of behaviour and interests. It has long been claimed that it is more common in males. This observed preponderance of males in autistic populations has served as a focussing framework in all spheres of autism-related issues, from recognition and diagnosis through to theoretical models and research agendas. One related issue is the near total absence of females in key research areas. For example, this paper reports a review of over 120 brain-imaging studies of social brain processes in autism that reveals that nearly 70% only included male participants or minimal numbers (just one or two) of females. Authors of such studies very rarely report that their cohorts are virtually female-free and discuss their findings as though applicable to all autistic individuals. The absence of females can be linked to exclusionary consequences of autism diagnostic procedures, which have mainly been developed on male-only cohorts. There is clear evidence that disproportionately large numbers of females do not meet diagnostic criteria and are then excluded from ongoing autism research. Another issue is a long-standing assumption that the female autism phenotype is broadly equivalent to that of the male autism phenotype. Thus, models derived from male-based studies could be applicable to females. However, it is now emerging that certain patterns of social behaviour may be very different in females. This includes a specific type of social behaviour called camouflaging or masking, linked to attempts to disguise autistic characteristics. With respect to research in the field of sex/gender cognitive neuroscience, there is emerging evidence of female differences in patterns of connectivity and/or activation in the social brain that are at odds with those reported in previous, male-only studies. Decades of research have excluded or overlooked females on the autistic spectrum, resulting in the construction of inaccurate and misleading cognitive neuroscience models, and missed opportunities to explore the brain bases of this highly complex condition. A note of warning needs to be sounded about inferences drawn from past research, but if future research addresses this problem of male bias, then a deeper understanding of autism as a whole, as well as in previously overlooked females, will start to emerge.

Sensory experiences questionnaire unravels differences in sensory profiles between MECP2-related disorders

The methyl CpG-binding protein-2 (MECP2) gene is located on the Xq28 region. Loss of function mutations or increased copies of MECP2 result in Rett syndrome (RTT) and MECP2 duplication syndrome (MDS), respectively. Individuals with both disorders exhibit overlapping autism symptoms, yet few studies have dissected the differences between these gene dosage sensitive disorders. Further, research examining sensory processing patterns in persons with RTT and MDS is largely absent. Thus, the goal of this study was to analyze and compare sensory processing patterns in persons with RTT and MDS. Towards this goal, caregivers of 50 female individuals with RTT and 122 male individuals with MDS, between 1 and 46 years of age, completed a standardized measure of sensory processing, the Sensory Experiences Questionnaire. Patterns detected in both disorders were compared against each other and against normative values. We found sensory processing abnormalities for both hyper- and hypo-sensitivity in both groups. Interestingly, abnormalities in MDS were more pronounced compared with in RTT, particularly with items concerning hypersensitivity and sensory seeking, but not hyposensitivity. Individuals with MDS also exhibited greater sensory symptoms compared with RTT in the areas of tactile and vestibular sensory processing and for both social and nonsocial stimuli. This study provides a first description of sensory symptoms in individuals with RTT and individuals with MDS. Similar to other neurodevelopmental disorders, a variety of sensory processing abnormalities was found. These findings reveal a first insight into sensory processing abnormalities caused by a dosage sensitive gene and may ultimately help guide therapeutic approaches for these disorders.

Alterations in Antioxidant Status and Erythrocyte Properties in Children with Autism Spectrum Disorder

Erythrocytes are responsible for the transport of oxygen within the organism, which is particularly important for nerve tissues. Erythrocyte quality has been shown to be deteriorated in oxidative stress conditions. In this study, we measured the same series of oxidative stress markers in plasma and erythrocytes to compare the differences between neurotypical children (controls) and children with autism spectrum disorder (ASD). We also focused on erythrocyte properties including their deformability, osmotic resistance, Na,K-ATPase activity, nitric oxide levels and free radical levels in children with ASD and controls. Greater oxidative damage to proteins and lipids was observed in the erythrocytes than in the plasma of ASD subjects. Additionally, antioxidant enzymes were more active in plasma samples from ASD children than in their erythrocytes. Significantly higher nitric oxide level and Na,K-ATPase enzyme activity were detected in erythrocytes of ASD individuals in comparison with the controls. Changes in oxidative status could at least partially contribute to the deterioration of erythrocyte morphology, as more frequent echinocyte formation was detected in ASD individuals. These alterations are most probably responsible for worsening the erythrocyte deformability observed in children with ASD. We can conclude that abnormalities in antioxidant status and erythrocyte properties could be involved in the pathomechanisms of ASD and eventually contribute to its clinical manifestations.