Age and regional differences in reliability and factor structure of the Zung Self-rating Scale in elderly Finnish men.

Regional and age differences in the reliability and factor structure of the SDS among elderly (65-84 years) men who were living either in eastern or in southwestern Finland were investigated. The Cronbach alpha coefficient was .803 for the eastern and .809 for the southwestern cohort; these figures were reasonably high. The tendency found was for the coefficient to be somewhat higher for the old (75-84 years) than for the young-old (65-74 years) population. In investigating the factor structure, a principal components factor analysis was performed, and the remaining factors were rotated using the orthogonal Varimax rotation algorithm. Three factors emerged for young-old men in the East, for young-old men in the Southwest and for old men in the Southwest, and four factors for old men in the East. The factor patterns of the first two factors showed similarities in both regions, but their order was different. "Loss of self-esteem" accounted for more of the common variance in the East and "agitated mood" in the Southwest. The differences in the third factor between the two regions were evident.