# Structural Analysis of the German Self‐Report Questionnaire for Anxiety and Depression in People With Disorders of Intellectual Development (SAD‐IE)

## TL;DR

This paper introduces a self-report questionnaire in German for assessing anxiety and depression in people with intellectual development disorders.

## Contribution

The study developed and validated the SAD-IE, a self-report tool tailored for individuals with disorders of intellectual development.

## Key findings

- A two-factor model (anxiety and depression) best represented the SAD-IE with strong fit indices (CFI = 0.956, RMSEA = 0.040).
- The questionnaire includes 39 items with sufficient discriminatory power, divided into 22 depression and 17 anxiety items.
- The SAD-IE is suitable for people with borderline, mild, or moderate DID and can be used as a screening or monitoring tool.

## Abstract

Anxiety disorders and depression are among the most common mental disorders in people with disorders of intellectual development (DID). As many symptoms are not directly observable, diagnoses should not be based solely on third‐party assessment. The aim of the study was the development and structural analysis of a self‐report questionnaire (SAD‐IE) for anxiety and depression in people with DID.

Based on the specific diagnostic criteria of DM‐ID‐2, a trial version of the SAD‐IE with 49 items was constructed in plain language. After contacting N = 233 institutions across all 16 German federal states, N = 286 adults with DID and their proxies were included. The factorial structure of the SAD‐IE was analyzed using confirmatory factor analysis for ordinal data (CFA, WLSMV estimation).

The CFA showed that a two‐factor model captured the latent structure of the SAD‐IE best (CFI = 0.956, TLI = 0.954, RMSEA = 0.040, SRMR = 0.069), with 39 of the original items having sufficient discriminatory power. The first factor, depression, was reliably represented by 22 items (r (it,c) = 0.520–0.770; α = 0.900, ω = 0.901) and the second factor, anxiety, by 17 items (r (it,c) = 0.504–0.796; α = 0.895, ω = 0.897).

The German SAD‐IE is a reliable self‐report questionnaire measuring the major symptoms of anxiety and depression in people with borderline, mild, or moderate DID. It provides the foundation for an urgently needed self‐assessment in addition to existing third‐party assessments, ensuring a more comprehensive diagnosis. Further evaluation in practice is recommended.

The SAD‐IE is a self‐report questionnaire in German that can be completed independently or with little assistance by people with borderline or mild to moderate DID. Instructions and items of the SAD‐IE are written in plain language, and pictures for augmentative and alternative communication (AAC) are provided.The SAD‐IE takes into account the deviations in anxiety and depression in people with DID compared to the general population.The SAD‐IE includes relevant items to diagnose anxiety and depression, as well as two additional items to measure general psychological distress.The SAD‐IE is designed as a screening tool but could also be used to monitor subjective changes in symptoms during follow‐up assessments or in research.

The SAD‐IE is a self‐report questionnaire in German that can be completed independently or with little assistance by people with borderline or mild to moderate DID. Instructions and items of the SAD‐IE are written in plain language, and pictures for augmentative and alternative communication (AAC) are provided.

The SAD‐IE takes into account the deviations in anxiety and depression in people with DID compared to the general population.

The SAD‐IE includes relevant items to diagnose anxiety and depression, as well as two additional items to measure general psychological distress.

The SAD‐IE is designed as a screening tool but could also be used to monitor subjective changes in symptoms during follow‐up assessments or in research.