Background
Quality of life (QOL) plays an important role in determining the improvement of patient care in Alzheimer’s disease. The simple and easily used Thai instrument for measuring QOL is still limited. 

Aims
This study aimed to translate the Quality of Life–Alzheimer’s Disease (QOL-AD) scale original version into a Thai version and test its psychometric properties. 

Method
A Thai version of QOL-AD was translated following the sequential method. The validation was tested in 136 pairs of patients and their caregivers. Mild to moderate Alzheimer’s patients were recruited from outpatient clinics at Chiang Mai Neurological Hospital and Chiang Mai Psychiatry Hospital from April to September 2012. Internal consistency, factor analysis, and construct validity were evaluated.

Results
Internal consistency of Thai QOL-AD version was good for both patients (0.82) and caregivers (0.82). The results of factor analysis indicated three factors (physical and psychological well-being, social well-being, and close interpersonal relationships) in the patient group, while four factors were found (social well-being, functional ability, psychological well-being, and physical well-being) in the caregiver group. The scaling success in the patient group was around 80–83 per cent for convergent validity, and 70–83 per cent for discriminant validity. The caregiver group showed higher scaling success in convergent validity except for the psychological well-being domain. The scaling success of discriminant validity was around 44–83 per cent for caregivers. 

Conclusion
The findings of the study demonstrate a good reliability of a Thai QOL-AD version for both patient and caregiver groups. Validity, especially in the caregiver group, might need to be re-examined.