Background Prevalence of neurocognitive disorder with Lewy bodies (NCDLB) is low in Asian populations, which may partially reflect its diagnostic difficulty. The Mayo Fluctuations Scale, a short questionnaire that evaluates cognitive fluctuation, has been shown to significantly differentiate NCDLB from Alzheimer’s disease.

Aim This study aimed to develop the Mayo Fluctuations Scale-Thai version and assess its validity to screen NCDLB in an elderly population.

Methods The Mayo Fluctuations Scale was translated into Thai. The process involved back-translation, cross-cultural adaptation, field testing of the prefinal version, as well as final adjustments. From all patients attending the Psychiatric and Memory Clinic at Ramathibodi Hospital, 135 patients accompanied by their primary caregivers were included. Caregivers were interviewed by research assistants using a four-item scale, and psychiatrists determined patients’ diagnosis based on the diagnostic and statistical manual of mental disorders (DSM)-5 criteria. Evaluations performed by psychiatrists and research assistants were blinded.

Results  Seventeen participants had been diagnosed with major NCDLB. At a cut-off score of 2 or over, the Mayo Fluctuations Scale exhibited excellent performance to differentiate major NCDLB from other major neurocognitive disorders (NCDs), with a sensitivity of 94.1% and a specificity of 71.4%, and acceptable performance to differentiate mild NCDLB from other mild NCDs, with a sensitivity of 60% and a specificity of 93.1%.

Conclusion The Mayo Fluctuations Scale-Thai version is an excellent screening tool for major NCDLB and an acceptable tool that may be used with other additional tests for mild NCDLB. The tool is practical for use in memory and psychiatric clinics. Further validation studies in participants with other specific clinical conditions are required.