Fig. 3

Internal consistency and factor structure of the Severity of Dependence Scale for central nervous system depressants. Evidence of acceptable internal consistency of the scale was found according to the Cronbach’s alpha coefficient (α = 0.73). A single-factor solution was extracted. The factor matrix showed that all items loaded strongly on this factor, with correlation coefficients ranging from 0.42 to 0.87. Scree plot test indicated clear debris after the first factor. These results underline the uni-dimensionality of the SDS in measuring psychological dependence of CNSDs in older patients