Sex Differences in Autism Spectrum Disorder: a Review

Area of Science:

• Neuroscience
• Genetics
• Endocrinology

Background:

• Neurodevelopmental disorders (NDDs) exhibit a notable male preponderance.
• The underlying biological mechanisms for male vulnerability and female protection are not fully understood.
• Understanding these sex differences is critical for advancing NDD etiology and treatment.

Purpose of the Study:

• To review current findings and theories on the male preponderance of NDDs, with a specific focus on autism.
• To explore genetic, epigenetic, hormonal, and environmental factors contributing to sex-based differences in NDD risk.
• To discuss potential explanations such as female underdiagnosis and multi-hit hypotheses.

Main Methods:

• Literature review of recent research on the biological basis of sex differences in NDDs.
• Synthesis of theories regarding genetic burden, sex-specific mutations, and epigenetic modifications.
• Analysis of the role of sex chromosomes and hormones, including fetal testosterone.
• Consideration of neuroendocrine, immune pathways, and diagnostic biases.

Main Results:

• Females may have a higher genetic burden, while males may be more susceptible to specific genetic or epigenetic changes.
• Sex chromosomes and hormones, particularly fetal testosterone, play a role in male vulnerability.
• Interactions between hormonal, neurotransmitter, neuropeptide, and immune pathways are implicated.
• Female underdiagnosis and a multi-hit hypothesis are considered as contributing factors.

Conclusions:

• Multiple biological and potentially social factors contribute to the male preponderance observed in NDDs.
• Further research is needed to elucidate the complex interplay of genetics, hormones, and environment in sex-specific NDD risk.
• Addressing potential underdiagnosis in females is crucial for a comprehensive understanding and effective treatment of NDDs.