The subjects in the study group had a mean age of 71.1 years (SD=7.5, range=60–94), a mean education level of 13.4 years (SD=2.8, range=1–17), a mean score for cerebrovascular risk factors of 7.6 (SD=3.8, range=0–21), and a mean score on the Cumulative Illness Rating Scale of 6.0 (SD=2.8, range=0–16). More than one-half of the subjects (59%, N=145) were women. The mean scores on the Hamilton depression scale at intake and 1 year, respectively, for the four diagnostic groups were as follows: major depression, 23.0 (SD=6.2) and 14.8 (SD=6.8); minor depression, 13.3 (SD=4.8) and 10.4 (SD=5.4); subsyndromal depression, 13.9 (SD=2.9) and 11.5 (SD=6.1); and nondepressed, 5.0 (SD=2.5) and 5.5 (SD=4.3).
A higher initial score for cerebrovascular risk factors had a significant independent association with a higher 1-year score on the Hamilton depression scale (coefficient=0.03, SE=0.01, F=7.4, df=1, 242, p=0.007) and with the 1-year depression diagnosis group (coefficient=–0.09, SE=0.04, χ2=5.2, df=1, p=0.02). The association between cerebrovascular risk factors and 1-year Hamilton depression score remained significant when also controlled for initial Hamilton depression score (coefficient=0.02, SE=0.01, F=4.0, df=1, 241, p=0.04) but not when additionally controlled for initial score on the Cumulative Illness Rating Scale (F=1.6, df=1, 240, p=0.20). The association of initial cerebrovascular risk factors with the 1-year depression diagnosis group did not remain significant when also controlled for initial depression diagnosis (χ2=2.8, df=1, p=0.10) or initial score on the Cumulative Illness Rating Scale (χ2=1.6, df=1, p=0.21). In these regressions, a higher initial cumulative illness rating was independently associated with both higher 1-year Hamilton depression score (coefficient=0.05, SE=0.01, F=10.4, df=1, 240, p=0.001) and the 1-year depression diagnosis group (coefficient=–0.17, SE=0.06, χ2=7.5, df=1, p=0.006). Also controlling for antidepressant treatment did not change any of these findings.
Initial score for cerebrovascular risk factors did not have a significant independent association with later-onset depression (χ2=0.6, df=1, p=0.45). No individual cerebrovascular risk factor had a significant independent association with either 1-year Hamilton depression score or depression diagnosis group.