Methodological complexities in the diagnosis of major depression in youth: an analysis of mother and youth self-reports.

OBJECTIVE: Considering the well-documented low level of agreement between youth and parent reports on the diagnosis of major depressive disorder (MDD), uncertainties remain as to the informativeness of discrepant youth and parent reports in clinical studies. To this end we evaluated whether morbidity and functional correlates on the diagnosis of MDD in youth vary by informant source. METHODS: The sample consisted of 186 pairs of independently assessed mother and youth self-reports on the diagnosis of MDD using structured diagnostic interviews ascertained in a large study of youth with and without attention deficit hyperactivity disorder of both genders. Subjects were also assessed on measures of interpersonal, school, and family functioning as well as prior treatment history. RESULTS: The diagnosis of MDD endorsed by youth self-report only when compared with that reported by the mother was characterized by significantly: shorter duration episode, later age at onset, milder depression-associated impairment, less impairment in interpersonal functioning, lower rates of comorbid disorders, and decreased likelihood to receive any course of treatment for depression. The morbidity and dysfunction associated with MDD varied significantly by informant source, and followed a dose-response association with the highest morbidity associated with the concurrent reports of the youth and the mothers, followed by mother report alone, with the least morbidity and dysfunction when endorsed by youth alone. CONCLUSIONS: These findings suggest that exclusive reliance on youth self-reports may identify a mild form of depression associated with limited morbidity and disability compared with that identified by parental reports.

Different brain networks mediate task performance in normal aging and AD: defining compensation.

OBJECTIVE: To determine whether the pathologic mechanisms of AD alter the brain networks subserving performance of a verbal recognition task. BACKGROUND: Functional imaging studies comparing task-related activation in AD patients and controls generally have not used network analysis and have not controlled for task difficulty. METHODS: H2 15O PET was used to measure regional cerebral blood flow in 14 patients and 11 healthy elders during the performance of a serial verbal recognition task under two conditions: low demand, with study list size (SLS) equal to one; and titrated demand, with SLS adjusted so that each subject recognized words at 75% accuracy. The Scaled Subprofile Model was used to identify networks of regionally covarying activity across these task conditions. RESULTS: In the elders, higher SLS was associated with the recruitment of a network of brain areas involving left anterior cingulate and anterior insula (R2 = 0.94; p < 0.0001). Three patients also expressed this network. In the remaining patients, higher SLS was associated with the recruitment of an alternate network consisting of left posterior temporal cortex, calcarine cortex, posterior cingulate, and the vermis (R2 = 0.81, p < 0.001). Expression of this network was unrelated to SLS in the elders and more intact AD patients. CONCLUSIONS: The patients' use of the alternate network may indicate compensation for processing deficits. The transition from the normal to the alternate network may indicate a point where brain disease has irreversibly altered brain function and thus may have important implications for therapeutic intervention.