Gastrointestinal Manifestations and Associated Comorbidities in Children with Autism Spectrum Disorder: A Cross-sectional Analysis from South India

Abstract

Background:

Gastrointestinal (GI) symptoms are frequently reported in children with autism spectrum disorder (ASD) and may significantly impact behavior, sleep, adaptive functioning, and the severity of autism. This study aims to explore the relationship between GI symptoms and these factors in children with ASD.

Methods:

We investigated 96 children and adolescents with ASD aged 3–18 years attending an autism clinic in South India. Parents were interviewed using a semi-structured proforma that gathered information on GI symptoms, sociodemographic details, medical history, and treatment history. Behavioral problems were assessed using the Strengths and Difficulties Questionnaire-2 (SDQ-2), ASD severity was measured using the Indian Scale for Assessment of Autism (ISAA), and sleep issues were evaluated using the Children’s Sleep Habits Questionnaire (CSHQ) for autism. Statistical analyses were conducted to determine the predictive value of assessment scores on GI symptoms in two groups: (a) those with mild to moderate ASD and (b) participants aged less than or equal to six years versus more than six years.

Results:

Constipation and dietary problems were the most commonly reported (82.29%), followed by dyspepsia and reflux (44.79%), pica (36.46%), abdominal pain (26.04%), and diarrhea (14.58%). Holding all other predictor variables constant, constipation increased by 20% (odds ratio [OR] = 1.201) for unit increases in speech-language communication scores. Abdominal pain decreased by 24.5% (OR = 0.755) for unit increases in peer problems scores. Excessive flatulence decreased by 64.2% (OR = 0.358) for unit increases in conduct problems score. Finally, pica was found to increase by 23.2% (OR = 1.232) for unit increases in the sensory patterns score.

Conclusions:

The GI symptoms can negatively impact sleep and behavior in children with ASD, spotlighting the importance of routine GI screening in this population. Clinicians should be particularly vigilant in cases where symptoms suggest a higher likelihood of GI issues to enhance the quality of care for children with ASD.

Keywords

Autism spectrum disorder GI issues comorbidities strengths and difficulties questionnaire behavioral problems

Key Messages:

The GI symptoms are prevalent in children with ASD, with constipation and dietary problems being the most common.

The GI symptoms are associated with various comorbid conditions, including behavioral problems, sleep problems, and ASD severity.

Routine GI screening is crucial for children with ASD to improve their quality of care and overall well-being.

Autism spectrum disorder (ASD) is seen in 1 in every 100 children in the world, according to the World Health Organization (WHO).¹ In India, it is estimated to be 1 in every 89 children, according to a study by INCLEN.² ASD is a neurodevelopmental disorder primarily characterized by atypical development in social, language, and cognitive domains. It is now understood that it involves a dysfunctional central nervous system, not just the brain. Several comorbidities have been associated with ASD, and it is understood that these comorbidities may be homotypic or heterotypic. Homotypic comorbidities are other disorders within the same class (coexisting neurodevelopmental disorders such as attention-deficit hyperactivity disorder [ADHD] and intellectual disability [ID]), and heterotypic comorbidities, on the other hand, are those from a different diagnostic class (mood disorders, anxiety, sleep disorders, etc.).³ Many of these comorbidities may not meet formal diagnostic criteria. However, they significantly impact the quality of life for children with ASD and their families, highlighting the need for further study.

Gastrointestinal (GI) issues are another common comorbidity in children with ASD, with prevalence rates ranging from 9% to 91%, depending on the study and population examined.¹ In a study of Indian children with ASD, 34.5% of the participants reported GI issues. The most common symptoms reported were diarrhea, constipation, gastroesophageal reflux disease (GERD), and abdominal pain. The study also found that those with GI symptoms harbored a higher autism severity, behavior problems, and sleep issues.⁴ The mention of GI symptoms as a part of ASD has been present since Leo Kanner reported eating problems in the majority of ASD children in his sentinel work.⁵ These comprise food selectivity, food refusal, and poor oral intake. A comprehensive meta-analysis revealed that children with ASD are four times more likely to develop GI issues than children without ASD. The most commonly described GI symptoms were constipation, diarrhea, abdominal pain, and reflux.^6,7

Lower GI symptoms have been linked to sensory difficulties and anxiety in individuals with ASD, suggesting a potential role of sympathetic nervous system activation associated with GI disorders in this population.⁸ This connection underscores the complex interplay between physiological and psychological factors in ASD. Externalizing behavioral problems, such as hyperactivity and peer relationship difficulties, have been observed at higher rates in children with ASD who experience GI problems compared to those without.⁹ This association highlights the potential far-reaching effects of GI discomfort on social interactions and daily functioning. Equally important are the internalizing behavioral problems associated with GI issues in ASD. Notably, constipation has been linked with heightened stress, anxiety, and sleep disturbances.^10–12 These findings suggest that GI symptoms may contribute to a cascade of comorbid conditions, potentially exacerbating the challenges faced by individuals with ASD.

Relevance and Additions to the Field

The Indian dietary landscape, which includes spice-heavy meals, fiber-rich vegetarian diets, and unique cultural feeding practices, differs significantly from Western diets and may influence gut microbiota composition and GI symptomatology in children with ASD. Additionally, socioeconomic factors and disparities in healthcare access may affect the reporting, diagnosis, and management of GI symptoms in Indian children with ASD. Despite the well-established association between GI issues and behavioral problems, sleep disturbances, and ASD severity in Western populations, there is limited evidence on whether these relationships hold in the Indian context. Early-life gut colonization, traditional feeding habits, and healthcare-seeking behaviors may contribute to differences in the prevalence and severity of GI symptoms, making it essential to explore these factors within a South Indian cohort.

This study aims to bridge this knowledge gap by profiling GI symptoms in Indian children with ASD using both parent-reported data and standardized assessments. It further investigates the associations between GI symptoms, behavioral problems, and sleep disturbances while considering potential influences of cultural and dietary factors. This research addresses these gaps and provides region-specific insights currently missing from global literature. The findings can contribute to better clinical screening protocols, dietary interventions, and healthcare strategies tailored to the needs of Indian children with ASD, ultimately improving the management of GI symptoms in this population.

Hypothesis

The GI symptoms in children with ASD are associated with increased severity of behavioral problems, sleep disturbances, and overall autism severity.

Aims

The aim of this study was to comprehensively profile the GI symptoms commonly reported in children and adolescents with ASD while also investigating their relationship with various comorbidities.

Objectives

This study centers on children and adolescents with autism spectrum disorder (ASD) to examine three primary concerns: the association between gastrointestinal (GI) symptoms and sleep patterns, the link between GI symptoms and behavioral challenges, and the correlation between GI symptoms and autism severity.

Methods

Study Setting and Design

We conducted a cross-sectional study investigating 96 children and adolescents aged 3–18 (median age: 66 months, interquartile range [IQR]: 50.5 months) diagnosed with ASD at a tertiary care center in South India. Parents participated in a semi-structured interview that gathered detailed information on the child’s GI symptoms, sociodemographic data, medical history, and treatment history.

Participants

Participant recruitment occurred between March 2023 and January 2024, upon which the estimated sample size of 96 was reached and recruitment was concluded. We employed a consecutive sampling method during routine consultations. This approach ensured a representative sample of the ASD population attending the clinic during the study period. To ensure consistency and reliability in data collection, all interviews were conducted by clinicians who underwent standardized training in the study protocol and interview techniques. The clinicians were MBBS graduates, employed as junior research fellows at the center, who were trained in administering the questionnaires and collecting information using the proforma. This approach minimized inter-interviewer variability and enhanced the quality of the collected data.

All children who had a prior diagnosis of an ASD given by the child and adolescent psychiatrist at the center were included. A medical record review and interview by the research team confirmed it. Diagnostic criteria were those of ASD according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Inclusion also required a score of 70 or above on the Indian Scale for Assessment of Autism (ISAA), a validated tool for diagnosing and classifying ASD severity.¹³ We excluded pediatric patients who were critically ill and those with GI symptoms attributed to a physical etiology.

Measures

Modified Kuppuswamy Scale

The Modified Kuppuswamy Scale assessed participant families’ socioeconomic status (SES). This scale classifies families into five socioeconomic categories: upper class, upper-middle class, lower-middle class, upper-lower class, and lower class. The classification is primarily based on three factors: family income, education, and profession of the head of the household.¹⁴

Behavioral Problems

Externalizing and internalizing behavioral problems were assessed using the parent-reported Strengths and Difficulties Questionnaire (SDQ-2).¹⁵ This scale has high test–retest reliability and internal consistency and has also been validated in the Indian population. The SDQ captures externalizing behaviors (conduct problems and hyperactivity) and internalizing behaviors (emotional symptoms and peer problems).¹⁶ While the SDQ helps assess general behavioral difficulties, it is not specifically tailored for children with autism. Combining SDQ with autism-specific tools like the ISAA provides a more accurate and holistic understanding of a child’s clinical profile.

Gastrointestinal Symptoms

GI symptoms were assessed using two complementary tools:

A Semi-structured Proforma

This was developed specifically for this study, targeting common GI symptoms reported in ASD populations based on a comprehensive literature review. Symptoms assessed included constipation, diarrhea, dyspepsia, abdominal pain, excessive flatulence, perianal itching, pica, and dietary issues (e.g., food selectivity, aversion to solids or liquids, feeding difficulties, trouble chewing or swallowing). This proforma additionally probed into parental concerns about past and current GI problems. Symptoms were coded as either present (further classified as current or past) or absent. Finally, caregivers rated symptom severity on a 5-point Likert scale, ranging from mild (1) to severe (5).

The Gastrointestinal Symptom Inventory for ASD (GISSI-17)

This is a 17-item checklist focusing on key GI symptoms commonly seen in the ASD population, such as constipation, diarrhea, and GERD.¹⁷

Indian Scale for Assessment of Autism

The ASD severity scores were measured using the ISAA.¹³ The tool has been standardized and validated for the Indian population, and it evaluates severity across five distinct domains: Social Relationship and Reciprocity, Emotional Responsiveness, Speech-Language and Communication, Behavior Patterns, and Sensory aspects. The total ISAA score was used to classify participants into mild (less than 107) or moderate-to-severe (107 or more) ASD categories.

Child Sleep Habits Questionnaire (CSHQ)

The CSHQ modified for ASD was used to evaluate sleep-related difficulties. Though the original CSHQ is designed for children aged 3–10, the modified version has been validated for use in children and adolescents aged 3–18 with ASD. The CSHQ studies multiple domains of sleep, including bedtime resistance, sleep duration, night awakenings, and parasomnias.¹⁸ Although the original CSHQ has been validated in the Indian population, the version modified for ASD has not been.

Medical Comorbidities

The semi-structured proforma collected details of medical comorbidities such as neurological disorders (seizures, visual impairment, hearing impairment, and other neurological disorders), respiratory illness (asthma, pneumonia, otitis media, frequent upper respiratory tract infections), anemia, and vitamin deficiencies. Regression in developmental milestones, specifically in speech and language domains, was also recorded based on parental reports combined with the Speech and Language subsection of the ISAA, which includes whether speech has been acquired and subsequently lost. The definition provided in the ISAA has been adopted as the operational definition to assess speech regression.

The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist was used as the reporting guideline for the study, and it has been uploaded as supplementary online material,¹⁹ and the diagnosis of psychiatric illness was per DSM-5.²⁰

Statistical Analysis

The data was analyzed using R Studio version 4.3.1.²¹ The categorical variables were reported using frequency tables. The continuous variables in the data were checked for normality using the Shapiro–Wilk test. The variables showing normal distribution were checked for statistical significance using parametric tests, and nonparametric tests were used for the ones showing a non-normal distribution. We divided the participants into mild and moderate ASD using the ISAA score cutoff of 106, available for 87 participants. Pearson’s correlation was used to ascertain the relationships between normally distributed variables, while Spearman’s rank correlation was utilized for non-normally distributed variables.

A multiple linear regression analysis evaluated the influence of the Child Sleep Habits Questionnaire for Autism (CSHQ-Autism), ISAA scores, and GI symptom severity on behavioral problems. Behavioral problems, including the SDQ and internalizing and externalizing scores, were treated as dependent variables and regression models were adjusted for potential confounders.

Subsequently, a logistic regression analysis was done to examine the predictive power of internalizing and externalizing behavior problem scores, along with other psychometric measures, on the presence of GI issues in children and adolescents with ASD. GI symptoms were the dependent variable, while age was considered a covariate in the model to adjust for its potential influence. We further explored the predictive capacity of assessment scores in two subgroups: participants aged less than or equal to six years and those more than six years and within the mild and moderate ASD sub-groups.

Results

Participant Demographics

The median age of participants was 66 months (IQR: 50.3). The sample consisted of 80 males (83.33%) and 16 females (16.67%). The majority of participants (61.46%) belonged to the upper middle class, followed by the lower middle class (20.83%), upper class (15.63%), and upper lower class (2.08%). Nutritional status assessment revealed that 59.38% were normal, 27.08% were underweight, and 13.54% were overweight. The chi-squared test did not indicate any significant associations between gender, socioeconomic class, and nutritional status across mild and moderate ASD groups. Notably, regression and sleep disturbances were significantly more prevalent in children with moderate ASD (Refer to Table 1: Sociodemographic and medical factors).

Table 1.

Sociodemographic and Medical Characteristics of Children with Mild and Moderate ASD.

Items	Mild ASD (n = 50)		Moderate ASD (n = 46)		Statistical Test
Items	n	%	n	%	Chi-square (χ²)
Gender
Males	40	80	37	80.4	−
Females	10	20	9	19.6	−
Socioeconomic class
Upper class	14	28	17	37	−
Upper middle class	17	34	8	17.4	−
Lower middle class	2	4	1	2.1	−
Upper lower class	1	2	0	0	−
Missing data	16	32	20	43.5	−
Comorbidities
Medical comorbidities	13	26	13	28.3	0.98
Psychiatric comorbidities	3	6	3	6.5	1
Developmental regression	16	32	22	48	0.02*
Nocturnal enuresis	5	10	6	13	0.88
Sleep disturbances	13	26	24	52.2	0.01*
BMI
Underweight	4	8	1	2.2	−
Healthy	17	34	19	41.3	−
Overweight	7	14	7	15.2	−
Obese	7	14	4	8.7	−
Missing data	15	30	15	32.6	−
Gastrointestinal symptoms (GISSI-17)
Diarrhea	33	66	33	71.73	−
Constipation	39	78	40	86.95	−
Gastroesophageal reflux	19	38	25	54.34	−

*Significant P values (<.05).

ASD: Autism spectrum disorder, BMI: body mass index. GISSI-17: gastrointestinal symptom inventory for ASD.

Sleep Disturbances

Among all participants, 38.5% screened positive for sleep disturbances on the CSHQ-Autism. The mean CSHQ-Autism score was 48.69 (standard deviation [SD]: 8.87). Significant differences between the two groups were seen in CSHQ-Autism, with moderate ASD groups having higher scores.

Behavioral Problems

The SDQ-2 revealed significant differences in total scores, internalizing scores, peer problems, and prosocial behaviors between mild and moderate ASD groups, with all measures being higher in the moderate group. The mean SDQ-2 total score was 20.06 (SD: 5.42), with internalizing and externalizing scores of 8.48 (SD: 3.67) and 11.58 (SD: 3.52), respectively.

Gastrointestinal Symptom Profile

Constipation was the most frequently reported GI symptom (82.29%), followed by dietary issues (82.29%), dyspepsia/GERD (44.79%), pica (36.46%), abdominal pain (26.04%), and diarrhea (14.58%). Parent-reported GI symptoms aligned closely with GISSI-17 screen results for constipation and GERD; however, GISSI-17-reported diarrhea was approximately five times higher in screening than parental reports. Perianal itching and excessive flatulence were excluded from the analysis due to low incidence. Regarding pica, crayons were the most ingested items, followed by rubber, paper, chalk, and mud (Figure 1).

Figure 1.

ASD: autism spectrum disorder, GISS-17: gastrointestinal symptom inventory for ASD.]

Correlation Analysis

Correlation analysis demonstrated positive relationships: SDQ-2 scores correlated with ISAA scores (+0.275), CSHQ-Autism scores (+0.344), and parent-reported GI symptom severity (+0.258). Internalizing scores positively correlated with ISAA scores (+0.305) and GI symptom severity (+0.251). Externalizing scores correlated positively with CSHQ-Autism (+0.415) as well as behavior patterns (+0.210) and sensory patterns (+0.218) from ISAA (Figure 2).

Figure 2.

SDQ-2: Strengths and Difficulties Questionnaire-2, ISAA: Indian Scale for Assessment of Autism, CSHQ-Autism: Child Sleep Hygiene Questionnaire-Autism.

Multiple Linear Regression

Multiple linear regression indicated that SDQ scores could be predicted by the CSHQ-Autism (E = 0.239, SE = 0.084, P value = .005) and GI symptom severity (E = 0.642, SE = 0.310, P value = .041). ISAA scores (E = 0.052, SE = 0.029, P value = .077) had a linear relationship but were not significant predictors of behavioral problems. There was a strong association between GI symptoms severity and behavioral problems (Table 2).

Table 2.

Multiple Linear Regression of Behavioral Issues with GI Symptom Severity, CSHQ-Autism, and ISAA Scores.

Parameter	Coefficient	Standard Error	P Value
GI symptom severity	0.642	0.310	.041*
CSHQ-Autism	0.239	0.084	.005*
ISAA score	0.0524	0.029	.077

*Significant P values (<.05).

GI: Gastrointestinal; CSHQ-Autism: Child Sleep Hygiene Questionnaire-Autism, ISAA: Indian Scale for Assessment of Autism.

Internalizing behavioral problems were predicted by ISAA (B = 0.04) and GI symptom severity (B = 0.44), yielding odds ratios (OR) of 1.04 and 1.55, respectively. Externalizing behavior was predicted by CSHQ-Autism (B = 0.193), indicating an OR of 1.21 (Refer to Figure 3: Multiple linear regression plots of behavioral problems v/s ISAA, CSHQ-Autism, GI symptom severity).

Figure 3.

SDQ-2: Strengths and Difficulties Questionnaire-2, ISAA: Indian Scale for Assessment of Autism, CSHQ-Autism: Child Sleep Hygiene Questionnaire-Autism.

Logistic Regression Analysis

Logistic regression assessed the relationships among behavioral problems, sleep disturbances, autism symptoms, and GI symptoms (including constipation, abdominal pain, dyspepsia, acid reflux, excessive flatulence, and pica). Diarrheal and dietary issues were excluded due to a lack of significant findings (Table 3).

Holding other variables constant, the odds of constipation increased by 20% (OR = 1.201) for each unit increase in speech-language communication score; abdominal pain decreased by 24.5% (OR = 0.755) per unit increase in peer problems score; excessive flatulence decreased by 64.2% (OR = 0.358) for each unit increase in conduct problems score; finally, pica increased by 23.2% (OR = 1.232) for each unit increase in sensory patterns score (Table 3).

Table 3.

Logistic Regression of GI Symptoms with Behavioral and Autism Severity Factors.

Parameter	β	eβ (Odds Ratio)	95% CI	P Value
Association of subscale scores with constipation
Social relationship and reciprocity	−0.001	0.998	(0.879, 1.136)	.197
Speech-language and communication	0.183	1.201	(1.054, 1.403)	.011*
Emotional symptoms	−0.142	0.866	(0.663, 1.121)	.279
Conduct problems	0.185	1.204	(0.867, 1.730)	.284
Hyperactivity	−0.050	0.950	(0.665, 1.337)	.771
Prosocial score	0.158	1.171	(0.823, 1.723)	.393
Peer problem score	0.044	1.045	(0.767, 1.433)	.771
Emotional responsiveness	0.038	1.039	(0.866, 1.268)	.683
Behavior patterns	−0.007	0.992	(0.871, 1.139)	.910
Sensory patterns	0.133	1.143	(0.907. 1.474)	.273
Cognitive patterns	0.006	1.006	(0.769, 1.331)	.961
CSHQ-autism	−0.007	0.992	(0.867, 1.144)	.914
Association of subscale scores with abdominal pain
Social relationship and reciprocity	0.005	1.005	(0.903, 1.122)	.913
Speech-language and communication	0.025	1.025	(0.927, 1.136)	.624
Emotional symptoms	0.069	1.072	(0.852, 1.352)	.548
Conduct problems	−0.225	0.797	(0.589, 1.051)	.121
Hyperactivity	−0.019	0.981	(0.726, 1.323)	.899
Prosocial score	0.008	1.009	(0.752, 1.355))	.951
Peer problem score	−0.280	0.755	(0.563, 0.988)	.048*
Emotional responsiveness	−0.024	0.976	(0.836, 1.137)	.755
Behavior patterns	0.042	1.043	(0.932, 1.167)	.455
Sensory patterns	−0.041	0.959	(0.787, 1.155)	.668
Cognitive patterns	−0.182	0.833	(0.643, 1.045)	.924
CSHQ-Autism	0.005	1.005	(0.901, 1.117)	.936
Association of subscale scores with dyspepsia/acid reflux
Social relationship and reciprocity	−0.010	0.989	(0.903, 1.122)	.828
Speech-language and communication	−0.028	0.972	(0.889, 1.059)	.521
Emotional symptoms	0.007	1.007	(0.822, 1.234)	.941
Conduct problems	0.080	1.083	(0.852, 1.386)	.514
Hyperactivity	0.060	1.062	(0.828, 1.366)	.629
Prosocial score	0.060	0.879	(0.676, 1.132)	.322
Peer problem score	0.048	1.049	(0.828, 1.333)	.685
Emotional responsiveness	−0.128	0.981	(0.852, 1.127)	.788
Behavior patterns	0.025	1.026	(0.935, 1.129)	.587
Sensory patterns	0.029	1.030	(0.876, 1.214)	.717
Cognitive patterns	−0.015	0.984	(0.807, 1.196)	.878
CSHQ-Autism	−0.037	0.963	(0.876, 1.054)	.419
Association of subscale scores with excessive flatulence
Social relationship and reciprocity	−0.008	0.991	(0.772, 1.257)	.940
Speech-language and communication	−0.174	0.839	(0.607, 1.043)	.184
Emotional symptoms	−0.110	0.895	(0.574, 1.331)	.592
Conduct problems	−1.026	0.358	(0.106, 0.739)	.029*
Hyperactivity	0.913	2.492	(1.059, 9.912)	.102
Prosocial score	0.129	1.138	(0.440, 1.550)	.636
Peer problem score	−0.153	0.857	(0.663, 2.017)	.617
Emotional responsiveness	−0.176	0.837	(0.508, 1.118)	.334
Behavior patterns	0.079	1.082	(0.844, 1.428)	.538
Sensory patterns	0.108	1.115	(0.802, 1.581)	.511
Cognitive patterns	−0.156	0.855	(0.541, 1.252)	.448
CSHQ-Autism	0.138	1.148	(0.887, 1.551)	.309
Association of subscale scores with pica
Social relationship and reciprocity	−0.062	0.939	(0.835, 1.045)	.267
Speech-language and communication	−0.001	0.998	(0.908, 1.096)	.982
Emotional symptoms	0.054	1.055	(0.843, 1.323)	.633
Conduct problems	−0.088	0.915	(0.870, 1.193)	.517
Hyperactivity	0.143	1.154	(0.870, 1.565)	.332
Prosocial score	−0.114	0.892	(0.855, 1.437)	.424
Peer problem score	0.009	1.104	(0.669, 1.179)	.446
Emotional responsiveness	0.133	1.142	(0.981, 1.337)	.087
Behavior patterns	0.133	0.954	(0.860, 1.053)	.363
Sensory patterns	0.209	1.232	(1.024, 1.514)	.034*
Cognitive patterns	−0.028	0.971	(0.780, 1.204)	.793
CSHQ-Autism	−0.016	0.983	(0.889, 1.082)	.742

*Significant P values (<.05).

CI: Confidence interval; CSHQ-Autism: Child Sleep Hygiene Questionnaire-Autism.

Discussion

Our investigation of GI disturbances identified constipation and dietary problems as the most commonly reported symptoms, affecting 82.29% of our sample. This was followed by dyspepsia and reflux, which were reported in 44.79% of the sample. Additional symptoms included pica (36.46%), abdominal pain (26.04%), and diarrhea (14.58%). In a focused analysis using the GISSI-17, which assessed only diarrhea, constipation, and reflux, we found that constipation was again reported at 82.29%, while reflux was noted at 45.83%, and diarrhea at 68.75%. The discrepancy in diarrhea rates may arise from the GISSI-17’s inability to differentiate between true diarrhea and encopresis related to constipation,¹⁷ potentially inflating the number of children screened as positive for diarrhea. While most participants were categorized as upper middle class or above on the modified Kuppuswamy scale, data was missing for 36 out of 96 participants, representing a limitation in our study.

Our study revealed significant associations between GI symptoms, behavioral problems, sleep disturbances, and autism severity in children in the South-Indian demographic. The mean SDQ-2 total score was 20.06 (SD: 5.42), indicating a high level of behavioral problems in our sample. We established that behavioral problems in children and adolescents with ASD, coupled with GI issues, could be predicted by sleep disturbances, GI symptom severity, and autism severity. This is in keeping with existing literature indicating that behavioral problems and sleep disturbances are more prevalent among children with ASD who also experience GI disturbances.^22,23 Notably, the internalizing score correlated positively with GI symptoms and autism severity, while externalizing problems were associated with sleep disturbances. This could indicate that GI symptoms in ASD may be linked to interoceptive challenges or heightened internalizing behaviors.^24,25

Our logistic regression analysis provided further insights into specific GI symptoms and their associations with ASD characteristics. Further analysis indicated that constipation could be predicted by speech and language impairments, consistent with prior studies suggesting that communication difficulties may hinder children’s ability to express their urges effectively, leading to avoidance behaviors regarding bowel movements.²⁶ Additionally, sensory issues were predictive of pica, corroborating findings from other research that highlight a higher prevalence of atypical eating behaviors among children with sensory processing difficulties.²⁷

Interestingly, abdominal pain was found to decrease with increased peer problems (OR = 0.755), possibly due to emotional distress overshadowing physical discomfort or behavioral adaptations that compel children with ASD to ignore pain to fit in socially. Increased peer interaction, even if problematic, could provide a distraction from physical symptoms. Children might downplay their pain to avoid appearing weak or different from their peers, and this could be a coping mechanism to maintain social connections, even if those connections involve peer problems.²⁸ It is also possible that children who report more peer problems also have other characteristics (e.g., higher tolerance for discomfort, different coping styles) that were not measured in the study and that influence their reporting of abdominal pain. The inverse correlation between abdominal pain and peer problems may also reflect stress-induced analgesia, where social distress alters pain perception or increased social engagement distracting from GI discomfort. Similarly, reduced flatulence in children with conduct problems could be linked to dietary differences, increased physical activity improving gut motility or stress-related gut function changes. These findings highlight the complex interplay between behavior, stress, and GI symptoms in ASD, warranting further investigation.

Similarly, excessive flatulence decreased with increased conduct problems (OR= 0.358), which may be attributed to behavioral changes diverting attention from gas-related discomfort or increased physical activity mitigating gas buildup. Children with conduct problems may have different dietary habits (e.g., less consumption of gas-producing foods) than those without. Acute stress can alter GI function, potentially decreasing gas production or increasing expulsion in some individuals. Children with conduct problems may experience more frequent activation of the stress response, leading to these physiological changes. It could also be the case that caregivers of children with conduct problems underreport excessive flatulence due to focusing on more prominent behavioral issues.

Physical examination findings revealed abnormalities in only 24 out of 96 participants, with halitosis and poor dental hygiene being the most common issues identified. This suggests that the GI disturbances observed were likely functional rather than organic, potentially linked to the enteric nervous system’s role.²⁹

Significant differences emerged between mild and moderate ASD groups concerning comorbidities like developmental regression and sleep disturbances, which were more prevalent in the moderate group. Additionally, assessment scores across multiple domains highlighted these distinctions, with the moderate ASD group showing significantly higher median scores in sleep anxiety/co-sleeping, total CSHQ-Autism score, peer problems, total SDQ-2 score, internalizing score, and lower adaptive functioning on the VABS-2 (refer to Table 4). The SDQ-2 scores further indicated significant behavioral differences between these groups, particularly in total and internalizing scores. Our study’s gender distribution (83.33% male, 16.67% female) aligns with the typical male predominance observed in ASD.⁴ The nutritional status of our sample (59.38% normal weight, 27.08% underweight, 13.54% overweight) highlights the importance of considering nutritional factors in ASD management, especially given the high prevalence of dietary problems observed. The authors found no significant differences when comparing the two groups below and above six years.

Stress and anxiety, which are common in children with ASD, can influence gut motility and microbiota through the gut–brain axis, contributing to GI symptoms. Dysregulated autonomic responses and sensory sensitivities may exacerbate issues like constipation and abdominal pain. Given these established links, the regression analysis allowed the exploration of the impact of behavioral factors on GI symptoms, providing insight into the interplay between psychological and physiological aspects of ASD.

Table 4.

Assessment Scores for Mild and Moderate ASD Groups.

Subscale Items	Range	Mild ASD (n = 50)	Moderate ASD (n = 46)	Statistical Test
Subscale Items	Range	Median (IQR)	Median (IQR)	Mann–Whitney U Test
Child sleep habits (CSHQ-autism)
Sleep initiation/duration	6–18	6 (2.75)	7 (2)	0.496
Sleep anxiety/co-sleeping	5–15	13 (4.75)	14 (2)	0.010*
Night walking/parasomnias	5–15	7 (1.75)	7 (3)	0.117
Daytime alertness	6–18	8 (4)	8 (4)	0.824
Total score	23–69	32 (4.75)	35 (5.75)	0.038*
Emotional and behavioral difficulties (SDQ-II)
Conduct problems score	0–10	3 (3)	3 (2.75)	0.697
Hyperactivity	0–10	6.5 (2.75)	7.5 (2)	0.149
Peer problem score	0–10	5 (2)	6 (2)	0.021*
Emotional symptoms	0–10	2 (3)	3.5 (3)	0.081
Prosocial score	0–10	5 (2.75)	3 (2)	<0.001*
Total score	0–40	17.74 (5.37)	19.98 (4.16)	0.026*
Internalizing score	0–20	7.76 (3.24)	9.37 (2.49)	0.008*
Externalizing score	0–20	9.90 (3.16)	10.54 (2.79)	0.294
Autism profile (ISAA)
Emotional responsiveness	5–25	10 (3.75)	15 (4)	−
Behavior patterns	7–35	14 (4)	21 (6.5)	−
Sensory aspects	6–30	10 (2)	13 (2)	−
Cognitive component	4–20	9.5 (2.75)	10 (2)	−
Social relationship and reciprocity	9–45	23.78 (4.80)	31.41 (5.64)	−
Speech-language and communication	9–45	20.66 (4.64)	27.43 (5.69)	−
Total score	40–200	89.70 (9.47)	119.85 (10.09)	−
Adaptive functioning (VABS-2)
Adaptive behavior composite	20–160	68.95 (9.25)	59.36 (10.77)	0.003*

*Significant P values (<.05).

ASD: Autism spectrum disorder, CSHQ-Autism: Child Sleep Hygiene Questionnaire-Autism, SDQ-2: Strengths and Difficulties Questionnaire-2, ISAA: Indian Scale for Assessment of Autism, ABS-2: Vineland Adaptive Behavior Scale-2.

Strengths and Limitations

Our study has several strengths. It is novel in investigating GI disturbances within the Indian demographic. It includes a broad age range, measures autism severity comprehensively, and explores associations between sleep and behavioral problems. Notably, we identified correlations between abdominal pain and peer problems as well as excessive flatulence and conduct problems—findings not previously reported in this population. Our study’s limitations include the fact that we could not use gold standard tests for screening or diagnosis of GI symptoms. The GISSI-17 only screens for diarrhea, constipation, and gastroesophageal reflux. However, our survey revealed pica, abdominal pain, and dietary problems as other frequently reported symptoms by supplementing the GISSI-17 with our own semi-structured proforma. Given that the data collection instruments utilized relied on parental reports, there is a potential for both underreporting and overreporting of symptoms. Another limitation of our study is that although the SDQ helps identify social challenges in children with ASD, it is not specifically designed to assess autism. As such, the Peer Problems and Prosocial Behavior subscale scores may reflect core autism features rather than distinct behavioral problems, requiring careful interpretation by practitioners.

Additionally, screening for ID was not done. Since we found a correlation between ASD severity and GI symptoms, the impact of ID on GI symptoms among children and adolescents with ASD is an important area that could not be investigated. The authors acknowledge several potential biases in their study. First, they recognize the risk of parental recall and reporting bias stemming from the reliance on parent-reported questionnaires. Additionally, socioeconomic bias may be present, as the study was conducted in an urban center, with most participants from upper-middle and upper-class backgrounds. Finally, cultural bias is possible since the study was conducted in South India, which may not produce similar results in Western countries.

Clinical Implications

GI disturbances are prevalent in children with ASD and contribute significantly to sleep disturbances and behavioral problems. Clinicians should routinely screen for GI disturbances in this population. The most reported symptoms include constipation, pica, dietary issues, diarrhea, abdominal pain, dyspepsia, and acid reflux—particularly noting that pica often goes overlooked despite its high incidence. Such a proactive screening approach could lead to timely interventions that improve GI health and overall behavioral outcomes, ultimately enhancing the quality of life for affected children and their families.

Furthermore, the nutritional status of children with ASD (27.08% underweight, 13.54% overweight in our sample) underscores the need for comprehensive nutritional assessment and management as part of routine care. The high prevalence of dietary problems (82.29%) further emphasizes this need.

Future Directions

As a pilot study, our findings warrant further exploration through research involving larger sample sizes. There is an urgent need for a validated questionnaire focused on common GI symptoms in children with ASD; our semi-structured proforma may serve as a foundation for developing such a tool. In particular, children with regressive ASD may exhibit more pronounced behavioral problems related to anxiety, self-injury, and aggression than their nonregressive counterparts. While our study noted significant differences in developmental regression between mild and moderate ASD groups, future research should specifically compare GI symptoms and behavioral problems in regressive versus nonregressive ASD. Additionally, our logistic regression analysis revealed intriguing relationships between specific GI symptoms and ASD characteristics (e.g., constipation and speech-language impairments, pica, and sensory issues). These associations warrant further investigation to understand their underlying mechanisms and potential clinical implications.

Conclusions

This study highlights the high prevalence of GI disturbances in children with ASD, particularly constipation and dietary issues. Significant associations were found between GI symptoms, behavioral problems, sleep disturbances, and autism severity. These findings underscore the need for routine GI screening in ASD children to improve overall well-being and clinical care.

Supplemental Material

Supplemental material for this article available online.

Footnotes

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Declaration Regarding the Use of Generative AI

None used.

Ethical Approval

The study was approved by the Institutional Ethics Committee of St. John’s Medical College (IEC No 14/2023).

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Informed Consent

The children gave their assent, and the parents or legal guardians gave written consent to participate in this study.

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