We sometimes encounter presenile or elderly patients with a mood disorder who subsequently develop dementia. They are often referred to us under the diagnosis of refractory depression also showing a variety of adverse effects related to psychotropics.
Dementia with Lewy bodies (DLB) has been established as one of the three major types of dementia, along with Alzheimer's disease (AD) and vascular dementia. According to the diagnostic criteria for DLB, in principle, the typical clinical symptoms include progressive, reduced cognitive function, variable, visual hallucinations and Parkinsonism.1 It has been said that more than half of DLB patients are diagnosed with depression during their clinical course. Previous researchers have reported that the association between depression and DLB is stronger than that of other dementia causing illnesses. For example, McKeith et al. found that the prevalence of depressive symptoms was higher in patients with DLB than in patients with AD.2
Some patients develop depression as a prodromal, early symptom and subsequently start to show the symptoms that fulfill the DLB criteria. As early as the 1980s, Reding et al. reported that patients with depression who also showed some of the following characteristic symptoms were likely to develop dementia in the future: the manifestation of a confused state after the administration of low-dose tricyclic antidepressants and the presence of extrapyramidal signs. This report seems to indicate the relationship between DLB and depression. In addition, a study examining patients with so-called pseudo-dementia reported that five of 16 patients with dementia secondary to depression were subsequently diagnosed with Parkinson's disease plus dementia.3 Therefore, accurate early diagnosis may improve the prognosis for such a patient, as well as their quality of life.
It is well known that DLB patients often show hypersensitivity to psychotropics, including antipsychotics. DLB patients also occasionally develop autonomic nervous system (such as respiratory/circulatory system) dysfunction. Taken together, electroconvulsive therapy (mECT, ECT) and repetitive transcranial magnetic stimulation (rTMS) appear to be preferable to pharmacotherapy for patients with DLB. Thus, in this study we also evaluated the efficacy and safety of these treatments.