Spanish adaptation and validation of the ALS Depression Inventory-12 (ADI-12) in patients with Amyotrophic Lateral Sclerosis.

Background: Patients with Amyotrophic Lateral Sclerosis (ALS) have a higher prevalence of mood disorders, including depression, than the general population. Non-specific measurement instruments have been used to evaluate depression in these patients, which complicates accurate diagnosis. The ALS Depression Inventory (ADI-12) exclusively assesses depressive symptoms in patients with ALS.

Aim: To adapt and validate the ADI-12 in a Spanish sample.

Methods: A selective design was used with 74 patients with ALS, using the ADI-12 questionnaire. The original instrument was translated and back-translated into Spanish. The internal structure, temporal stability, convergent, and discriminant validity of the instrument were analyzed.

Results: Two confirmatory models showed internal validity (p = 0.502 for the one-factor model, p = 0.507 for the two-factor model). The Cronbach's alpha (0.900 in the first measurement and 0.889 in the second one) indicated a high internal consistency of the test. The Pearson correlation (0.90) indicated high temporal stability. In terms of convergent validity, the ADI-12 showed moderate correlations with the Beck Anxiety Inventory (BAI) (0.51-0.58), and low correlations with time since ALS diagnosis (-0.26 to -0.27).

Limitations: The main limitation of the present study was the small sample size.

Conclusions: The ADI-12 is fitted to a single general factor of depression, and the scale shows high internal consistency and high temporal stability, therefore, its use is recommended for the diagnosis of depression in patients with ALS.