Cortical Brain Perfusion and Cognitive Event Related Potentials in Patients with Psychomotor Retardation in Late Onset Depression.

BACKGROUND: Late onset depression is characterised by pronounced cognitive impairment, more somatic complaints and psychomotor retardation. Psychomotor slowing may be due to impairment in either motor or cognitive domain. Electrophysiology may be particularly convenient as a tool in studies of psychomotor retardation, as it can separate central cognitive processing from the motor processing. SUBJECTS AND METHODS: In this study we compared event related potentials (ERP) in the two groups of patients with late onset depression and psychomotor slowing as measured by reaction time (RT): a group of patients with lower RT was compared to a group with a higher RT. Twenty patients with late onset depression were included in the study after they had reached remission. Four weeks after reaching remission patients were reevaluated clinically using Hamilton Depression Rating Scale, Mini Mental State Examination, and with a computer version of the Stroop task. ERP, accuracy and RTs were simultaneously recorded. Both groups of patients aditionaly underwent a perfusion SPECT imaging. RESULTS: There were no differences between the short and long RT groups of patients in amplitudes of the late positive Stroop related potentials. The group of patients with longer RTs showed significant hyperperfusion in precentral gyrus, parietal regions, cuneus and hypoperfusion within insular, frontal, temporal and limbic (parahyppocampal gyrus and anterior cingulate) cortices, as well as cerebellum. CONCLUSION: We found no ERP differences between the two groups suggesting that although patients may differ on psychomotor retardation measured as RT, their cognitive abilities may be quite similar. Perfusion SPECT imaging however revealed a significant difference between them. This may be due to a process of compensation and applying different strategies to cope with cognitive impairment in the two groups.

Executive dysfunction in late-onset depression.

OBJECTIVE: Depression in the elderly is frequently accompanied by cognitive impairment. Executive dysfunction, including disturbances in planning, sequencing, organizing and abstracting has been reported in late-onset depression. They were found to be associated with relapse and recurrence of geriatric major depression and with residual depressive symptoms. SUBJECTS AND METHODS: A group of patients with late-onset depression, compared with age matched healthy volunteers, were assessed for deficits in executive functioning. We used the computer version of Stroop Color-Word test enabling more detailed reaction time analysis. Severity of depression was evaluated with Hamilton depression rating scale and Geriatric depression scale. RESULTS: The preliminary results of a study show that patients with late-onset depression have increased absolute reaction times in Stroop colour-word test. Significant differences in the magnitude of individual interference effects pointing towards a characteristic change in attentional processes in depressed patients. CONCLUSION: The preliminary results of a study comparing a group of elderly depressed patients with a control group of older healthy volunteers confirm changes in executive functions.

Cognition in late onset depression.

The aim of study was to assess cognition in patients with late onset depression in a symptom-free remission period measuring event-related potentials and reaction times (RT) in a modified computer version of the Stroop test. Thirty four patients with late-onset depression were included after they had reached remission. They were compared to age-, gender- and education-matched healthy controls. Each participant completed a single item computer version of the Stroop Color-word task using verbal response mode. EEG and RT were simultaneously recorded. RTs were significantly prolonged in patients in all conditions of the Stroop paradigm, and the interference effect was significantly greater in patients compared to controls. Results also revealed abnormal late positive Stroop related potentials in the period of about 500-600 ms period corresponding to the so-called P300b wave. Our study supports the view that patients with late onset depression are also cognitively impaired and that this impairment persists in the period of early remission. Using more sensitive ERP measurement of the Stroop task we demonstrated impaired information processing at an earlier, pre-response related stage.