Objective We attempted to clarify the factors related to the aggravation of depression in patients with subacute myelo-optico-neuropathy (SMON) caused by clioquinol intoxication more than 35 years previously. Methods We investigated changes in the depressive mental states that occurred with aging in 19 Japanese SMON patients (mean age, 78.3 years; range, 66-89 years) according to their scores on the Japanese version of the Zung Self-rating Depression Scale (SDS), which were obtained 3-10 years previously and their current scores. The depressive state was further evaluated using simultaneous semi-structured interviews. Results The depressive mental states of 6 patients, whose current total SDS scores had increased by ≥10% in comparison to the previous score, were considered to have been aggravated with aging. The mean current total SDS score of these six patients was significantly higher than the mean score of the 13 patients whose conditions were not aggravated. Among the 20 SDS questionnaires, the patients whose conditions were aggravated showed significantly higher scores in diurnal variation, sleep disturbance and weight loss. The semi-structured interviews revealed that physical disabilities due to the sequelae of SMON, a lack of acceptance of SMON, and a decline in social activities were important factors in the aggravation of their depressive mental states with aging. Conclusion The maintenance of social activities with public support was important for coping among Japanese SMON patients with a depressive mental state, especially those who could not walk independently or who could not go outside freely without assistance.
Keywords: SMON; Zung Self-rating Depression Scale; aging; depressive mental state; subacute myelo-optico-neuropathy.