Executive dysfunction and visuospatial ability among depressed elders in a community setting

Abstract

Visuospatial ability is frequently compromised among elderly depressed patients, but it is unclear whether the impairment is a consequence of a visuospatial memory deficit or of an executive dysfunction that impacts visuospatial ability. The Boston Qualitative Scoring System is a method of scoring the Rey–Osterrieth Complex Figure (ROCF) that assesses the process used to draw the figure, the executive aspect of the task, as well as the accuracy and location of the completed elements. The hypotheses that executive scores as measured by the BQSS would separate diagnostic groups and that executive function would mediate the relationship between depression and nonverbal recall were tested using a between groups design with elderly depressed volunteers ( N=31) and healthy controls ( N=31). Participants were screened for other Axis I disorders with the Structured Clinical Interview for DSM-IV Diagnosis, diagnosed for major depression per DSM-IV criteria, and administered the ROCF. The copy and recall drawings were scored using BQSS criteria, and scores were grouped into executive and drawing scores from both copy and recall phases. Executive scores during the copy phase and drawing scores from the recall phase separated the diagnostic groups [ F(1,59)=4.14, P=.05] and [ F(1,59)=6.88, P=.01], respectively. Follow-up ANCOVAS showed that copy Planning, the score that quantified the process by which the figure was drawn, separated the diagnostic groups. Planning also mediated the association between depression and the percent of the figure recalled after the short delay ( Z=1.84, P<.05). The significance of the depression-to-recall pathway was eliminated when Planning was controlled for, but Planning remained related to percent recalled [ B=−6.90, P<.007]. A dimension of executive dysfunction, represented here by Planning, may be one underlying source of the observed decline in nonverbal recall among elderly depressed patients. This result is consistent with the theory that dysfunction of the prefrontal cortex is a critical feature of late-life depression.