This case–control study was conducted at the Behavioral Medicine Department of Sultan Qaboos University Hospital (SQUH), a tertiary care teaching hospital in Muscat, Oman. The study was nested within a larger cross-sectional investigation that aimed to identify Hikikomori-like idiom of distress (HLID) among adults attending the department. Initial screening was carried out using the Hikikomori Questionnaire-25 (HQ-25), alongside the collection of socio-demographic information. Participants were subsequently invited to complete a structured diagnostic interview using the HiDE-I to allow for accurate case classification. Participants who completed the HiDE-I and met eligibility criteria for the CANTAB sub-study were invited to complete neuropsychological testing. Selection was non-random and depended on participant consent and logistical feasibility within the clinical setting. The resulting CANTAB group should therefore be regarded as a convenience subsample rather than a representative random sample of all 454 interviewed participants. Hikikomori case status in the present study was determined using the clinician-administered HiDE-I rather than HQ-25 screening scores alone.

The initial cross-sectional sample consisted of 1,200 Omani nationals aged between 18 and 59 years, recruited from outpatients attending the Behavioral Medicine Department at SQUH and their accompanying attendees. Of these, 454 participants completed the HiDE-I structured diagnostic interview. The HiDE-I was incorporated into the study protocol from 1 January 2024 onward, following its publication (Teo et al., 2023); participants recruited before this date completed HQ-25 screening only, and from 1 January 2024 onward all eligible attendees were invited to complete the HiDE-I irrespective of HQ-25 score. From this group, 150 participants were selected to complete CANTAB testing, including 85 patients and 65 attendees. The 150 participants who completed CANTAB were selected from the 454 HiDE-I-interviewed participants by convenience sampling, prioritizing available HiDE-I-positive cases to maximize case numbers within the resource and scheduling constraints of CANTAB administration (equipment availability and staff time), with non-cases recruited concurrently from the same clinic population. Participants were not randomly or systematically sampled from the full interviewed cohort, which may limit representativeness of the CANTAB sub-sample relative to the broader 454-participant group; sociodemographic comparability between the two is presented in Table 2. Cognitive performance outcomes were examined across multiple domains. The importance of each cognitive domain was evaluated using standardized β coefficients derived from adjusted regression models ( Figure 1).

Hikikomori cases were identified using the Hikikomori Diagnostic Evaluation Interview (HiDE-I), a structured clinical assessment tool that aligns with international diagnostic criteria for prolonged social withdrawal (Teo et al., 2023).

The HiDE-I is a structured clinician-administered interview assessing the frequency and purpose of outings, duration of withdrawal, social participation and interaction, and distress, concern by others, or functional impairment associated with withdrawal. For this neurocognitive study, participants classified as pathological, at-risk, or resembling Hikikomori were included as HiDE-I-positive cases, irrespective of HQ-25 score; participants meeting none of these categories were classified as non-cases. The HiDE-I classifies respondents through three sequential criteria (Teo et al., 2023). Criterion I (physical withdrawal): during the preceding month, the respondent spent three days or fewer per week engaged in an activity outside the home lasting at least one hour. Criterion II (distress and impairment): the withdrawal is associated with distress or loneliness in the respondent, concern or help-seeking by family members, or impairment in occupational or academic functioning, home life, or friendships, assessed through the corresponding HiDE-I item sets. Criterion III (duration): the length of time the respondent has been physically withdrawn. Respondents not meeting Criterion I were classified as non-cases. Respondents meeting Criterion I but not Criterion II were classified as Hikikomori resemblance. Respondents meeting Criteria I and II were classified by duration of withdrawal as pathological Hikikomori (six months or more) or at-risk Hikikomori (less than six months). The HiDE algorithm further subdivides the under-six-month group into at-risk (less than three months) and pre-pathological (three to less than six months); for this study these two bands were combined into a single at-risk category, as neither meets the six-month duration threshold for pathological Hikikomori. Participants were therefore classified into four groups: non-case, Hikikomori resemblance, at-risk Hikikomori, and pathological Hikikomori.

For the purposes of this neurocognitive case-control study, a broad HiDE-I case definition was used. This definition classified participants as Hikikomori cases if they met criteria for any HiDE-I category: pathological Hikikomori, at-risk Hikikomori, or Hikikomori resemblance. Participants who did not meet criteria for any of these three categories were classified as non-cases. This broader definition was deliberately adopted because cognitive differences associated with social withdrawal may not be limited to fully pathological Hikikomori but may also be present in earlier or subthreshold stages of withdrawal.

A total of 54 participants were identified as Hikikomori cases and agreed to participate in the study, yielding a response rate of 93%. All cases were evaluated by two trained mental health professionals, each experienced in assessing social withdrawal disorders. Inter-rater reliability was assessed using percent agreement between two independent clinicians who conducted the HiDE-I interviews. Initial agreement on Hikikomori classification across the three subtypes was 96%. Discrepant cases were subsequently reviewed through a structured consensus adjudication process involving joint discussion of interview data and clinical criteria, after which full agreement (100%) was reached. This consensus-based approach was used to ensure diagnostic accuracy rather than to inflate reliability estimates.

Non-case participants were recruited from the Behavioral Medicine Department at SQUH and confirmed to be Hikikomori-free through the Hikikomori Diagnostic Evaluation Interview (HiDE-I). To be included, participants were required to have no history of prolonged social withdrawal and not meet criteria for any HiDE-I subcategory, including pathological, at-risk, or resemblance Hikikomori. A total of 96 non- cases consented to participate, yielding a response rate of 87%.

Inter-rater reliability for non-case classification was assessed using percent agreement between two independent clinicians who conducted the HiDE-I interviews. Initial agreement on control status was 95%. Discrepant cases were subsequently reviewed through a structured consensus adjudication process involving joint discussion of interview data and clinical criteria, after which full agreement (100%) was reached. This consensus approach was applied to ensure accurate exclusion of Hikikomori rather than to inflate reliability estimates.

Hikikomori cases and non-cases were assessed using standardized screening and diagnostic tools. The Arabic validated version of the Hikikomori Questionnaire (HQ-25), which has demonstrated excellent internal consistency (Cronbach’s alpha = 0.91), was used to assess social withdrawal (Al-Sibani et al., 2023). Sociodemographic data were also collected using a structured questionnaire administered in the previous cross-sectional study, providing initial data on social withdrawal patterns and participant characteristics. Participants completed a structured self-report sociodemographic questionnaire covering age, gender, marital status, education, monthly household income, employment status, governorate of residence, and whether they had children. For the present analysis, age was grouped as 18–29, 30–39, and ≥40 years; income as <1,000, 1,000–1,999, 2,000–2,999, and ≥3,000 OMR; employment as employed or unemployed; marital status as never married or ever married; and education as <12, 12, or >12 years. Governorates represented in the sample are listed in Table 2. In addition to Hikikomori-specific assessments, participants underwent cognitive testing using the Cambridge Neuropsychological Test Automated Battery (CANTAB) (Fray et al., 1996). CANTAB assesses core domains such as executive function, memory, attention, and response inhibition, and has been validated in both clinical and non-clinical populations across diverse cultural contexts (Airaksinen et al., 2005; Bourke et al., 2012; Green et al., 2019; Kim et al., 2014).

CANTAB is a computerized neuropsychological assessment tool widely used in psychiatric research to measure executive function, attention, working memory, and processing speed. Testing was conducted via touchscreen devices, with responses recorded automatically. A trained examiner provided standardized instructions to ensure comprehension. The testing was conducted in a quiet environment, and headphones were provided when necessary to minimize auditory distractions.

CANTAB assessed multiple cognitive domains relevant to this study. Executive function was measured using the Intra/Extra Dimensional Set Shift (IED), which evaluates cognitive flexibility, and the One Touch Stockings of Cambridge (OTS), which assesses planning and problem-solving skills. Working memory was tested using the Spatial Working Memory (SWM) and Spatial Span (SSP) tasks. Attention and processing speed were assessed through the Rapid Visual Information Processing (RVP) task, while Pattern Recognition Memory (PRM) was used to evaluate visual memory recall. The CANTAB tasks and corresponding outcome measures used in this study are summarized in Table 1.

Data was collected through standardized interviews and computerized cognitive assessments. Trained mental health professionals administered all assessments following standardized protocols. HiDE-I interviews took place in private clinical settings, and CANTAB assessments were conducted in a controlled environment with sufficient time for task completion. Assessors administering the CANTAB were blinded to participants’ Hikikomori case or control status to reduce the risk of performance and observer bias.

Data were analyzed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA). Descriptive statistics were used to summarize participant characteristics, with means and standard deviations reported for continuous variables and frequencies with percentages for categorical variables. Independent samples t-tests were conducted to compare cognitive performance between Hikikomori cases and non-cases. Associations between Hikikomori status and cognitive performance were examined using linear regression models, including both crude models and adjusted models controlling for age, gender, education level, income, employment status, governorate, and marital status. Regression assumptions were assessed prior to analysis. Normality of residuals was evaluated using visual inspection of histograms and Q-Q plots, while homoscedasticity and linearity were assessed through residual scatterplots. Reaction time and latency measures, which showed mild positive skew, were retained in their original scale, as residual diagnostics indicated acceptable approximation to normality and model fit. No variable transformations were required. To ensure robustness of findings, non-parametric sensitivity analyses were also performed, including Mann–Whitney U tests for group comparisons and Spearman’s rank correlation coefficients for associations. Results from these supplementary analyses were consistent with the parametric findings.

Sample size for the broader parent case–control study was calculated a priori using Rothman’s Episheet and was based on odds-ratio detection, assuming a control-to-case ratio of 1:1, a Zα value of 1.96, an exposure prevalence of 0.15, and 80% power to detect an odds ratio of 2.0. This calculation was not specifically tailored to the continuous CANTAB outcomes examined in the present neurocognitive sub-study. A two-group calculation based on an anticipated mean difference and variance would have been more directly appropriate.

The achieved case-to-non-case ratio was 54:96 (approximately 1:1.8), rather than the 1:1 ratio assumed in the parent-study calculation. With a fixed total sample size and similar group variances, unequal allocation generally provides less precision than equal allocation; however, recruiting additional non-cases can improve precision when the number of available cases is constrained. Because the original calculation was not based on the continuous CANTAB outcomes, the power implications of the achieved ratio were not quantified. The study may therefore have had limited precision for detecting small effects, and non-significant findings should not be interpreted as evidence of equivalence.

Given that 11 cognitive outcomes were examined, we additionally applied Benjamini–Hochberg false-discovery-rate correction (q = 0.05) to the adjusted-model p-values in Table 5. All five domains reported as significant in the primary analysis remained significant after correction. Under the more conservative Bonferroni correction (α = 0.0045), four of the five domains remained significant; immediate recall (p = 0.019) did not survive this stricter threshold and should be interpreted with additional caution. These results indicate that the pattern of findings is unlikely to be attributable to multiple testing alone, though replication in an independent, adequately powered sample remains warranted.

Table 2 presents the socio-demographic characteristics of participants who underwent CANTAB testing. Of the 150 participants included, 54 were classified as Hikikomori cases and 96 as non-cases based on the study’s HiDE-I-positive case definition, which included pathological, at-risk, and resembling presentations irrespective of HQ-25 score. Patients constituted 56.7% of the sample (n = 85), while attendees accounted for 43.3% (n = 65).

Among Hikikomori cases, the majority were female (70.4%) and aged 18–29 years (77.8%), compared with 62.5% and 67.7%, respectively, among non-cases. A higher proportion of cases were unemployed (85.2%) compared to non-cases (67.7%). Differences were also observed across family income categories, with cases more frequently represented in lower income brackets.

No substantial differences were observed between cases and non-cases with respect to marital status, parental status, educational attainment, or governorate of residence. Distributions across governorates reflected the clinic-based sample, with Muscat and Al Batinah accounting for the largest proportions in both groups.

Table 3 presents comparisons of cognitive performance between Hikikomori cases and non-cases. Across the full sample, Hikikomori cases demonstrated significantly poorer performance in visual processing accuracy, response latency, immediate recall, delayed recall, and planning efficiency (p < 0.05). No significant group differences were observed for planning latency, spatial working memory errors, or strategy use.

In subgroup analyses, patients with Hikikomori showed significantly poorer performance across multiple domains, including visual processing accuracy, memory recall, and planning efficiency. Among attendees, significant differences were observed for visual processing accuracy and planning efficiency; however, differences in immediate and delayed recall were not statistically significant. Supplementary nonparametric analyses (Mann–Whitney U tests) produced comparable results, supporting the robustness of these findings.

Table 4 presents the crude and adjusted associations between HiDE-I case status and cognitive performance for the full sample and the patient and attendee subgroups. In the full sample, case status was associated with lower visual-processing accuracy, slower response latency, poorer immediate and delayed recall, and lower planning efficiency after adjustment for sociodemographic variables. Among patients, adjusted associations remained statistically significant for immediate recall, delayed recall, and planning efficiency; the association with response latency was not statistically significant. Among attendees, adjusted associations were statistically significant for visual-processing accuracy and planning efficiency. Delayed recall was at the conventional significance boundary (p = .05), whereas immediate recall, response latency, planning latency, and the spatial working-memory measures were not statistically significant. These subgroup findings should be interpreted cautiously because of the smaller sample sizes and multiple outcomes examined.

Table 5 presents the standardized β coefficients for the association between HiDE-I case status and the cognitive outcomes in the adjusted full-sample models. The largest absolute standardized coefficients were observed for visual-processing accuracy and planning efficiency (β = −.453 for both), followed by response latency (β = .266), delayed recall (β = −.255), and immediate recall (β = −.201). All remaining cognitive domains showed non-significant associations. After Bonferroni correction, visual-processing accuracy (p = .001), planning efficiency (p = .001), response latency (p = .001), and delayed recall (p = .003) remained statistically significant. Immediate recall (unadjusted p = .019) did not meet the Bonferroni-adjusted threshold and should therefore be interpreted as suggestive. All five outcomes remained significant under the Benjamini–Hochberg false-discovery-rate procedure.

Independence from Emotional Distress

To evaluate whether the observed cognitive differences might reflect general psychiatric comorbidity rather than a Hikikomori-specific profile, we used DASS-21 depression, anxiety, and stress scores collected from all 150 CANTAB participants as part of the parent study. Hierarchical linear regression (sociodemographic covariates and patient/attendee status in Block 1, HiDE-I status in Block 2, DASS-21 subscales in Block 3; Table 6) showed that Hikikomori status contributed significant, substantial explained variance in every cognitive domain after adjustment (ΔR² = .037–.195, all p < .05), while emotional distress added negligible further variance once Hikikomori status was accounted for (ΔR² = .004–.012, all p > .50). Within HiDE-I-positive cases, Spearman correlations between depression severity and cognitive performance were non-significant for all five outcomes (n = 40 dual positive cases: p = .526–.920; n = 54 broader HiDE-I-positive group: p = .081–.889).

To examine whether current emotional-symptom severity accounted for additional variance in cognitive performance, exploratory hierarchical linear regressions were conducted using DASS-21 depression, anxiety, and stress scores available for all 150 CANTAB participants. Sociodemographic variables and patient-versus-attendee status were entered in Block 1, HiDE-I case status in Block 2, and the three DASS-21 subscales in Block 3. HiDE-I status increased explained variance across the five principal cognitive outcomes (ΔR² = .037–.195), whereas the DASS-21 block added ΔR² = .004–.012 and was not statistically significant in any model (all p > .50).

Spearman correlations between depression severity and the five cognitive outcomes were also non-significant in the dual-positive group (n = 40) and the broader HiDE-I-positive group (n = 54). In these exploratory analyses, current DASS-21 symptom severity did not explain significant additional variance after HiDE-I status. This reduces, but does not eliminate, concern that current depression, anxiety, or stress symptoms account for the observed cognitive differences. DASS-21 is not a diagnostic interview, and diagnosis-specific variables, neurodevelopmental conditions, substance use, and medication exposure were not modeled; consequently, these results cannot establish a Hikikomori-specific cognitive profile.

Table 6 Hierarchical linear regression examining the independent contribution of Hikikomori status and emotional distress (DASS-21) to CANTAB cognitive performance, after adjusting for sociodemographic factors and patient/attendee status (N = 150). Block 1 predictors: age, gender, education, income, employment status, governorate, marital status, patient-versus-attendee status. Block 2 predictor: HiDE-I Hikikomori status (0 = non-case, 1 = case). Block 3 predictors: DASS-21 depression, anxiety, and stress subscale scores. ΔR² = R² change contributed by each block. In these exploratory models, the DASS-21 symptom block did not explain significant additional variance after HiDE-I status. This finding reduces, but does not eliminate, concern that current depression, anxiety, or stress symptom severity accounts for the observed differences. Because DASS-21 is not a diagnostic interview and medication and diagnosis-specific variables were not modeled, the results cannot establish a Hikikomori-specific cognitive profile.

Hikikomori cases showed lower planning efficiency and slower response latency than non-cases after adjustment for sociodemographic variables. These findings indicate differences in selected aspects of executive and processing-speed performance associated with HiDE-I case status in this sample. Similar cognitive differences have been documented in several psychiatric conditions that may co-occur with Hikikomori (Bourke et al., 2012; Gau & Shang, 2010). However, the present study did not determine whether psychiatric comorbidity accounted for these domain-specific findings. The observed cognitive differences may be associated with functional withdrawal, but the direction and mechanism of this association were not tested in this cross-sectional study.

Prior research indicates that deficits in response inhibition and attentional shifting, commonly seen in social anxiety disorder, may contribute to social withdrawal (Pupi et al., 2025; Rhodes et al., 2005). Given the high prevalence of social anxiety in Hikikomori (Kato et al., 2024), these cognitive difficulties are consistent with, and may plausibly contribute to, the maintenance of avoidance behaviors (Lo et al., 2023), though the cross-sectional design cannot establish directionality. In addition to deficits in planning efficiency, Hikikomori cases also exhibited slower response times, suggesting broader differences in processing speed and cognitive efficiency that may further exacerbate withdrawal tendencies.

In this study, planning efficiency and visual processing accuracy showed the strongest associations with Hikikomori, which may reflect difficulties in goal-directed behavior and in the interpretation of environmental cues necessary for social interaction. These findings are consistent with evidence showing that executive dysfunction and attentional processing difficulties are linked to reduced social functioning and withdrawal in clinical populations (Bourke et al., 2012; Kim et al., 2014; Luciana & Nelson, 2002). The minimal associations observed for spatial working memory and strategy use suggest that Hikikomori is characterized by selective rather than global cognitive impairment, a pattern also reported in recent neuropsychological research on Hikikomori (Santona et al., 2023) and in studies demonstrating that only specific executive domains may be affected rather than overall cognitive capacity (Rhodes et al., 2005). This selective vulnerability highlights the importance of interventions that target planning, cognitive flexibility, and visual–attentional processing, rather than assuming a broad cognitive decline among Hikikomori individuals.

Hikikomori cases performed less well than non-cases on immediate and delayed memory-recall measures in the unadjusted analyses. Both associations remained statistically significant in the primary adjusted models; however, immediate recall did not survive the Bonferroni correction and should be interpreted as suggestive. Memory differences have also been reported in social anxiety disorder and other psychiatric conditions (Airaksinen et al., 2005). The present findings demonstrate an association between HiDE-I case status and memory performance but do not establish whether memory differences preceded, followed, or contributed to social withdrawal.

Hikikomori cases showed lower visual-processing accuracy than non-cases after adjustment for sociodemographic variables. This association remained statistically significant after correction for multiple testing. No statistically significant case–non-case differences were detected for spatial working-memory errors, planning latency, or strategy use. These non-significant results should not be interpreted as evidence that these domains were intact or equivalent between groups, because the study may have had limited precision for detecting smaller effects. These findings align with research showing that psychiatric conditions often affect distinct cognitive domains (Bourke et al., 2012; Kim et al., 2014; Luciana & Nelson, 2002).

Given that social anxiety disorder (SAD) is one of the most common comorbidities in Hikikomori (Lin et al., 2022; Pupi et al., 2025; Tateno et al., 2012), attentional and cognitive flexibility impairments—key features of SAD—are consistent with, and may plausibly contribute to, persistent withdrawal behaviors, though the cross-sectional design cannot establish directionality. SAD has been linked to difficulties in processing social cues and regulating attention and emotion (Bourke et al., 2012), which provides a possible contextual interpretation of the observed findings; however, this mechanism was not directly tested in the present study.

Furthermore, neuroimaging studies have shown that chronic social withdrawal is associated with changes in brain regions responsible for visual processing and attention, including the hippocampus, ventral striatum, and prefrontal cortex (Zovetti et al., 2021). These findings align with recent work on COVID-19-related isolation, which underscores the broader neurological and psychological consequences of prolonged social disengagement (Roza et al., 2020).

Hikikomori cases showed lower performance in selected measures of planning, visual-processing accuracy, response latency, and memory recall. No statistically significant differences were detected in the spatial working-memory measures, planning latency, or strategy use. This pattern is consistent with domain-specific rather than uniformly lower cognitive performance; however, the non-significant findings do not demonstrate equivalence or preserved functioning. Larger studies are needed to determine whether smaller differences are present in these domains.

Gender was included as a covariate in the adjusted regression models but was not formally tested as a moderator of the association between Hikikomori status and cognitive performance (i.e., no gender-by-case interaction term or gender-stratified model was fitted). The adjusted associations reported above therefore already account for gender differences in the sample but cannot speak to whether the Hikikomori–cognition association itself differs by gender. Testing this formally, ideally in a larger sample, is a priority for future research given the well-documented gender differences in cognitive performance in the general population (Camarata & Woodcock, 2006; Herlitz & Rehnman, 2008).

Hikikomori cases in this sample were more likely to be unemployed and to report lower household income than non-cases, consistent with prior work linking prolonged social withdrawal to reduced workforce participation (Nonaka & Sakai, 2021). Cases and non-cases differed descriptively in their employment and household-income distributions (Table 2). Employment and income were included as covariates in the adjusted cognitive models; however, no interaction, mediation, or socioeconomic-stratified analysis was performed. The present study therefore cannot determine whether socioeconomic factors caused social withdrawal or modified the association between HiDE-I case status and cognitive performance. These findings should be interpreted as characteristics of the study sample rather than evidence of a causal socioeconomic mechanism.

The cognitive differences observed in this study may identify domains worth assessing when planning future interventions. However, the present study did not evaluate cognitive remediation or any clinical intervention and therefore cannot establish treatment effectiveness. Future intervention studies should determine whether addressing planning, attention, processing speed, or memory improves functional or social outcomes among people with Hikikomori.

Several limitations should be considered. First, the case–control design precludes causal inference; cognitive differences may precede social withdrawal or emerge because of prolonged disengagement. Longitudinal studies are needed to clarify directionality. Second, multiple cognitive domains were examined, raising the possibility of type I error due to multiple comparisons. Although four of the five principal findings remained statistically significant after Bonferroni correction, immediate recall did not survive this conservative adjustment. The immediate-recall finding should therefore be interpreted cautiously and requires replication. Third, participants were recruited from a hospital-based behavioral medicine clinic, introducing potential selection bias that likely biases the sample toward more severe, help-seeking presentations and would tend to overestimate cognitive impairment relative to a community-representative sample; while inclusion of non-patient attendees broadened representation and may partly offset this, results may not fully generalize to community samples. Fourth, formal psychiatric diagnoses among non-case patients were not systematically catalogued. However, a post-hoc analysis using DASS-21 scores collected from the full CANTAB sample (see Independence from Emotional Distress, above) found that depression, anxiety, and stress severity did not explain the observed cognitive differences, and a within-patient subgroup analysis (Table 4), in which both cases and non-cases were drawn from the psychiatric patient population, also showed persisting cognitive differences by Hikikomori status. Together these reduce, though do not eliminate, the concern that general psychiatric comorbidity rather than Hikikomori-specific factors drives the findings. Fifth, CANTAB has not been formally validated against Omani normative data; it was selected for its non-verbal, examiner-independent design and its use across diverse clinical and non-clinical populations internationally (Bourke et al., 2012; Green et al., 2019; Kim et al., 2014), which supports cross-cultural applicability. Although the computerized, largely non-verbal format reduces some language and examiner effects, it does not eliminate cultural, educational, or contextual influences. Local psychometric and normative studies are therefore needed. Finally, medication status was not systematically assessed; psychotropic medications may influence attention, processing speed, and memory in either direction, and this — along with comorbidities beyond depression/anxiety/stress (e.g., ADHD, substance use) — remains an unaddressed potential confound for future replication.

Future research should combine longitudinal cognitive assessment with structured measurement of psychiatric diagnoses, neurodevelopmental conditions, emotional symptoms, and medication exposure. Structural and functional neuroimaging may help determine whether the observed behavioral differences correspond to changes in neural systems supporting attention, planning, and memory (Zovetti et al., 2021). Longitudinal designs would be required to examine whether these cognitive and neural differences precede prolonged withdrawal, emerge following withdrawal, or change during recovery or intervention. Cross-sectional neuroimaging alone would not establish a Hikikomori-specific mechanism. Because exposure and outcome were measured cross-sectionally, the study cannot determine whether cognitive differences preceded withdrawal, followed it, or arose from shared psychiatric, developmental, medication-related, or social factors.

Artificial intelligence tool (ChatGPT) was used solely for language editing and grammar refinement. The authors take full responsibility for the content.

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Published: 22 Sep 2026, 15:874

Published: 02 Sep 2026, 15:874

Published: 23 Jun 2026, 15:874

Published: 05 Jun 2026, 15:874

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Al Kharusi N, Al-Farsi YM, Chan MF et al. Executive Dysfunction and Memory Impairments in Hikikomori: A Neuropsychological Case-Control Study from Oman [version 4; peer review: 2 approved]. F1000Research 2026, 15:874 (https://doi.org/10.12688/f1000research.181828.4)

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Current Reviewer Status: ?

VERSION 4

PUBLISHED 22 Sep 2026

Revised

Reviewer Report 05 Oct 2026

Helena Vélez-Botero, National University of Colombia, Bogotá, Colombia 

Approved

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Reviewer Report 25 Sep 2026

Alicia Nevriana, Karolinska Institutet, Stockholm, Sweden 

Approved

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VERSION 3

PUBLISHED 02 Sep 2026

Revised

Reviewer Report 15 Sep 2026

Andrés Camilo Delgado Reyes, Universidad de Manizales (Ringgold ID: 27992), Manizales, Caldas, Colombia 

Helena Vélez-Botero, National University of Colombia, Bogotá, Colombia 

Approved with Reservations

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VERSION 2

PUBLISHED 23 Jun 2026

Revised

Reviewer Report 03 Aug 2026

Helena Vélez-Botero, National University of Colombia, Bogotá, Colombia 

Andrés Camilo Delgado Reyes, Universidad de Manizales (Ringgold ID: 27992), Manizales, Caldas, Colombia 

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Reviewer Report 29 Jul 2026

Alicia Nevriana, Karolinska Institutet, Stockholm, Sweden 

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