A preliminary profile of neuropsychological deficits associated with major depression.

A profile of neuropsychological deficits of clinically depressed (major depression) but otherwise unimpaired individuals is presented, based on a meta-analysis of all studies published since 1975 and meeting stringent methodological and sample selection criteria. Deficits are discussed separately for different cognitive areas in terms of mean size of deficit, variability between studies, variability of individual scores in depressed populations relative to that of controls, and expected proportion of depressed individuals scoring two standard deviations or more below the mean of controls. The neuropsychological deficits of individuals with major depression are shown to be consistent with a global-diffuse impairment of brain functions with particular involvement of the frontal lobes. Recent neuro-imaging studies also indicating frontal dysfunction in clinical (functional) depression are referred to. Both the severity and the profile of cognitive deficiencies in depression are postulated to be similar to those seen in moderately severe traumatic brain injury.