Mapping the affective syndrome in Alzheimer's disease.

D ementia due to Alzheimer's disease (AD) is becoming more frequent with the rapid growing of life expectancy and also with the continuous improvement of the clinical diagnosis 1. Neuropsychiatric symptoms are very common over the course of AD dementia, adding substantial burden for families and caregivers 2. These symptoms are usually fluctuating in intensity and are often difficult to be treated. Apathy is the most common behavioral disorder across all stages of AD 2,3. Depression and anxiety are also very common, especially in mild and moderate stages, frequently worsening cognitive and functional performances 2. The main neuropsychiatric symptoms of de-mentia can be easily assessed by the Neuropsychiatric Inventory (NPI) 4. The neural correlates of these behavioral symptoms have been explored in several structural neuroimaging studies, mainly with magnetic resonance imaging (MRI) using voxel-based morphometry (VBM). In one study 5 conducted with this technique delusions were associated with atrophy in the left frontal lobe, right frontoparietal cortex and left claustrum. Apathy was associated with atrophy in anterior cingulate, medial frontal cortex and putamen bilaterally, and also with the head of left caudate nucleus. Agitation correlated with gray matter loss in left insula and anterior cingulate cortex bilaterally. Another study 6 showed that agitation was related to atrophy in the left inferior and middle frontal/ insula and bilateral retrosplenial cortices. Aberrant motor behavior was related to atrophy in the right basal ganglia and right inferior frontal cortex, and depression, with atrophy in the left middle frontal cortex. Voxel-based cortical thickness (VBCT) also seems to be a good way to assess atrophy, allowing identification of structural changes several years before the emergence of demen-tia 7. In this issue of Arquivos de Neuro-Psiquiatria, Hayata and colleagues 8 used the VBCT technique to contrast AD dementia patients and elderly cognitively healthy controls, and found similar results to those reported with VBM 9. The investigators found widespread cor-tical atrophy in the AD group, involving the left middle and inferior temporal gyri, posterior regions of right superior temporal sulcus, isthmus of the cingulate gyrus, left posterior cin-gulate cortex, and right fusiform gyrus. They also found atrophy in the frontal and parietal lobes, insula, entorhinal cortex, precuneus and anterior cingular cortex, all of them bilaterally. The authors found significant correlations between affective syndrome (depression and anxiety) with reduced cortical thickness in the insula, lateral orbitofrontal and temporal pole, all from the right side. Conversely, they found no …