Mixed anxiety depression: taxometric exploration of the validity of a diagnostic category in youth.
BACKGROUND
Mixed anxiety depression (MAD) is a provisional diagnosis in the DSM-IV. This study determined whether MAD represents a discrete category thereby evaluating the validity of MAD as a diagnostic entity.


METHODS
Taxometric analyses and mixture modeling were used to discern whether MAD indicators constitute a distinct psychopathological category (i.e., a taxon) in a large school-based sample of adolescents (N=706).


RESULTS
Each taxometric procedure (MAXCOV, MAMBAC) identified a taxon with a prevalence of 13%+/-2%. A non-taxometric procedure (multivariate mixture modeling) also supported the existence of a taxon with a prevalence of 12%. Bootstrapping procedures were used to construct a measure of MAD (i.e., MAD-T). Scale construction suggested that MAD may be best represented by 12 criteria that largely overlap with the DSM-IV, though some modifications were suggested. Examination of the construct validity of the MAD taxon indicated that it is associated mood and anxiety symptoms. Taxon membership was predictive of the development of mood and anxiety disorders over a 14-month longitudinal follow-up.


CONCLUSIONS
This category should be studied in other populations including adult samples.


CONCLUSIONS
MAD appears to be a viable diagnostic category for youth though it is recommended that future revisions of the DSM emphasize somewhat different criteria for this diagnosis.
Schmidt
Norman B
NB
Department of Psychology, Florida State University, Tallahassee, FL 32306-1270, United States. Schmidt@psy.fsu.edu
Kotov
Roman
R
Bernstein
Amit
A
Zvolensky
Michael J
MJ
Joiner
Thomas E
TE
Lewinsohn
Peter M
PM
D000293:Adolescent; D001007:Anxiety / Q000150:complications*; D015331:Cohort Studies; D003863:Depression / Q000150:complications*; D006801:Humans; D009922:Oregon; D011569:Psychiatric Status Rating Scales; D000297:Psychology, Adolescent; D015203:Reproducibility of Results; D013577:Syndrome