Background: Depression is more prevalent in subjects with dementia than in those without it. Due to both psychological and biological risk factors it is suggested that a bimodal distribution of depressive symptoms exists with higher prevalence rates being found among patients suffering both with mild and with severe dementia.
Aim: To confirm or reject the hypothesis of a bimodal distribution of depressive symptoms.
Methods: A sample of 1,159 randomly selected nursing home patients was assessed using the Cornell Scale, the Clinical Dementia Rating Scale (CDR) and Lawton's Scale of the activities of daily living. Additionally, information was collected from the patients' records. A factor analysis of the Cornell Scale was performed.
Results: The use of antidepressants and demographic characteristics, except for gender distribution, did not differ across CDR groups. Patients with dementia had more symptoms such as anxiety, irritability, agitation, retardation, loss of interest, lack of joy and delusion than those without dementia. No symptom was more frequent among non-demented subjects. The factor analysis resulted in a five factors solution: 'mood', 'cyclic', 'physical', 'retardation' and 'behavioural' factor. The score on the mood subscale did not differ across CDR groups (p = 0.326), whereas the scores on the four other subscales increased with increasing CDR scores (p < 0.001).
Conclusion: We did not find a bimodal distribution of depressive symptoms. The explanation for the occurrence of the typical core symptoms of depression, the mood symptoms, is probably complex. The non-mood symptoms are probably strongly influenced by biological factors.
Copyright (c) 2008 John Wiley & Sons, Ltd.