Increased Parietal and Frontal Activation after Remission from Recurrent Major Depression: A Repeated fMRI Study

Nine patients with unipolar major depression were scanned with MRI twice over a 2-year period, and compared with 12 healthy control subjects. All patients fulfilled criteria for major depressive disorder, recurrent type, at first scanning. Level of depressive psychopathology was assessed by the Hamilton Depression Rating Scale. The participants had to work on a mental arithmetics/working memory task while in the MR scanner. The task consisted of single digits (1 to 9) that were shown to the participant, who had to add the numbers in successive pairs and press a response button when the sum was 10. Neuronal activation was recorded based on the BOLD contrast phenomenon in a functional MRI protocol. The results showed significant increase in activation for the patients in the inferior frontal gyrus and the superior and inferior parietal lobule at the second compared with the first MR scanning session. There were also significant correlations between the HDRS scores and neuronal activation which showed a negative correlation particularly in the inferior frontal and parietal lobe areas, which overlapped with similar areas activated in the healthy control participants. This may indicate normalization of brain activation in depressed patients as a function of time from an illness phase to a remission/recovery state.