Dimensions of manifest depression

Abstract

DEPRESSION is a complex psychiatric concept. The term is used to refer to subjective mood as well as to symptom syndromes associated with psychopathologic states called depression. As a psychiatric syndrome, depression is manifest in a number of signs and symptoms which distinguish the depressed patient from the normal. As in the case of other recognized syndromes, not all depressed patients evidence all symptoms, at least not to the same degree of intensity. An important question concerns characteristics of individual difference in depressed patients. If depressed patients vary in the nature and intensity of symptoms presented, what primary symptom dimensions are most useful in characterizing these individual differences ? Must variation in the symptomatology of depressed patients be accounted for in terms of a unique set of factors which are not recognized dimensions of psychiatric symptomatology in other patient populations, or is there a common set of factors which exist at different levels in various types of psychiatric patients including cases of depression? The methods of factor analysis were employed in the present investigation in an effort to provide answers to these questions. The factor analysis model assumes that observed behavior is complex and that it is determined by a parsimonious set of underlying factors, traits, or processes. Any given bit of observed behavior, such as rateable psychiatric symptomatology, may be determined by more than a single basic factor, and certainly several different measureable patient characteristics may result from the same underlying factor. To the extent that several measureable patient characteristics reflect a single underlying factor which exists at different levels in different individuals, these characteristics will tend to co-vary (or to be correlated). That is, an individual who is high on the underlying factor will tend to have high scores on the several characteristics reflecting that factor, and individuals who are low on the factor will have low scores on these same characteristics. It is through identification of sets of patient characteristics which tend to co-vary that factor analysis leads to inferences concerning the nature of primary sources of variance responsible for this co-variation. Thus, factor analysis is a methodology for the study of individual differences. The co-variation or correlation of symptom measures depends upon the fact that they reflect underlying factors which exist at different levels in different individuals.