Depressive illness, depressive symptomatology and regional cerebral blood flow in elderly people with sub-clinical cognitive impairment

Background: depressive illness in dementia is often assumed to be a unitary clinical phenomenon. Aim: to describe changes in patterns of depressive symptomatology with time, and associated changes in cerebral blood flow to the frontal and temporal regions. Method and results: 397 elderly people with sub-clinical cognitive dysfunction were observed over 3 years. Sixteen percent of them developed dementia during the study. The prevalence of depressive symptomatology was higher in this group than in the general population, especially in women, who also had higher recovery rates. A changing profile of depressive symptoms was found in depressed elderly people progressing to dementia, with fewer affective symptoms and increases in agitation and motor slowing. These changes were paralleled by greater reductions in left temporal regional cerebral blood flow than in non-depressed subjects with Alzheimer's disease. Conclusion: in dementia, there may be two separate and interacting depressive syndromes whose differentiation may be clinically important.