Sex and age differences of factor pattern and reliability of the Zung Self-rating Depression Scale in a Finnish elderly population.

Abstract

Sex and age differences on the Zung Self-rating Depression Scale and the reliability of the scale among an elderly population of 1358 were investigated. A principal-components factor analysis was performed, and the remaining factors were rotated using the orthogonal varimax rotation algorithm. Four factors emerged for young-old (60–74 yr.) men, three for old-old (75+ yr.) men, three for young-old (60–74 yr.) women, and four for old-old (75+ yr.) women. The first factor was similar for young-old men, old-old men, and young-old women, and dealt with “loss of self-esteem”. The first factor for old-old women dealt with “agitated mood with somatic symptoms”. The second factor was also similar for young-old men, old-old men, and young-old women, and it described “agitated mood with somatic symptoms”, being similar to the first factor for old-old women. The second factor for old-old women was similar to that of the first factor (“loss of self-esteem”) for the other three groups. The third factor for young-old men and old-old women described psychomotor retardation. For young-old women the theme of the third factor was “depressed mood”, and for old-old men the predominant theme was “somatic symptoms”. Somatic symptoms were the main theme of the fourth factor for young-old men and old-old women. These results showed that there are sex and age differences in the factor structure of the scale among the elderly population. Cronbach alpha coefficients were relatively high: 0.73 for young-old men, 0.75 for old-old men, 0.72 for young-old women and 0.77 for old-old women.