**Background:** Autism Spectrum Disorder (ASD) is a lifelong neurodevelopmental disorder with rising global prevalence, currently estimated at 1 in 100 children worldwide. In Lebanon, prevalence is substantially higher, affecting between 49 and 513 children per 10,000 across all regions. Early detection and intervention significantly improve outcomes in cognition, language, and adaptive behavior. While parents and teachers have been the focus of much ASD knowledge research, limited studies have examined the general population's understanding of ASD, particularly in Lebanon. This study aimed to assess ASD knowledge, beliefs, and sources of information in a Lebanese general population sample and identify factors influencing that knowledge.
**Methods:** A cross-sectional study was conducted across all districts in Lebanon from May to August 2022. The target sample size was calculated using Krejcie and Morgan's formula, yielding a minimum of 384 participants; after accounting for a 20% nonresponse rate, 500 participants were recruited. Inclusion criteria were adults aged >18 years. A questionnaire was developed based on prior ASD knowledge studies, translated into Arabic, and piloted on 25 Lebanese adults. The final instrument included three sections: socio-demographic characteristics, ASD knowledge, and beliefs about ASD. The Autism Spectrum Knowledge Scale, General Population Version (ASKSG) was used, comprising 32 items across five domains: etiology and prevalence (7 items), symptoms and behaviors (12 items), assessment and diagnosis (5 items), treatment (3 items), and outcomes and prognosis (5 items). Each correct answer scored 1; incorrect or "don't know" responses scored 0 (maximum total score 32). Knowledge levels were categorized using modified Bloom's cut-off: good (75–100%), moderate (50–75%), and poor (<50%). Data were analyzed using SPSS version 20.0 with chi-square tests and multivariable linear regression.
**Key Results:** The sample was predominantly female (68.6%), aged 35–49 (33.8%), university-educated (77.8% with bachelor's degree or higher), and resided in Mount Lebanon (68.2%). Although 88.8% had heard of ASD, only 8% rated themselves as familiar with it. Social media was the primary information source (54.34%). The mean total knowledge score was 13.8 (SD=6.69) out of 32 (43.1%), indicating poor overall knowledge. Domain-specific scores were: symptoms and behaviors 52% (moderate), outcomes and prognosis 43.4% (poor), assessment and diagnosis 39.2% (poor), etiology and prevalence 29% (poor), and treatment 26% (poor). Notable misconceptions included: 47.6% believed vaccines cause ASD, only 35% knew ASD is more common in boys, 53.2% incorrectly attributed ASD to maternal emotional deprivation, and only 21% and 11.4% identified advanced maternal and paternal age as risk factors, respectively. Regarding diagnosis, 42.8% believed ASD can only be diagnosed after age 4, and 37.6% thought it could be diagnosed using brain imaging alone. Knowledge scores differed significantly by gender (p<0.001), age group (p=0.012), and region of residence (p=0.026). Females, participants aged 25–34, and those living in Beirut demonstrated better knowledge. Knowing someone with ASD (p<0.001) and using social media as an information source (p<0.001) were also significantly associated with higher knowledge. Multivariable linear regression confirmed age (p<0.001), gender (p=0.012), region (p=0.026), knowing an ASD case (p<0.001), and source of information (p=0.002) as independent predictors of ASD knowledge.
**Clinical Implications:** This study reveals substantial knowledge gaps about ASD in the Lebanese general population, particularly regarding etiology, diagnosis, treatment, and prognosis. The high endorsement of the vaccine–autism myth (47.6%) is alarming as it may reduce vaccination rates and endanger public health. Misconceptions about diagnosis may contribute to delayed identification and intervention, while inaccurate beliefs about treatment could lead families to pursue ineffective therapies. The finding that social media is the primary information source (54.34%) presents both an opportunity and a risk, given the prevalence of health misinformation on these platforms. Targeted awareness campaigns using social media, schools, community centers, and healthcare settings are urgently needed to improve early detection, reduce stigma, and promote evidence-based interventions. Future studies should target early childhood educators, medical students, pediatricians, parents of children with ASD, teachers, and nurses. Study limitations include a non-representative sample (most participants from Mount Lebanon), reliance on self-reported data, and a relatively small sample size for the general population.