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 dysfunct ion 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 h ad higher recovery rates. A changing profile of depressive symptoms was fou nd in depressed elderly people progressing to dementia, with fewer affectiv e 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 depressi ve syndromes whose differentiation may be clinically important.