[Psychomotor retardation associated to depression differs from that of normal aging]

Psychomotor retardation (PMR) is a main symptom of depressive illness. In the elderly, it is associated with the severity of depression and poor prognosis. However, PMR is also commonly associated with normal aging, Therefore, depressive PMR is frequently misinterpreted as the age-related slowing in the elderly, which contributes to poor recognition of depression. Moreover, neurobiological and neuroanatomical studies on PMR hardly allowed to discriminate geriatric depression from normal aging. Reaction time experiments have rarely been tested in elderly population although they are particularly suited for examining PMR. We performed two reaction time experiments using an additive factor analysis in healthy and depressed old individuals with the hypothesis that PMR associated to depression differed from that of normal aging. Results showed that age-related PMR affected all stages of central nervous system information processing, while PMR associated with depression is limited to the components of response-selection and motor-adjustment. These results clearly show that PMR in geriatric depression differed from the age related slowing. Depression also spares stimulus preprocessing in old individuals as it did in younger adults.