Background: Depression is a common behavioral and psychological symptom of Alzheimer's disease (AD). The aims of the present study were to determine the rate of depression in Taiwanese patients with AD using the National Institutes of Mental Health Provisional Criteria for Depression in AD (NIMH-dAD criteria) and to investigate the association of depression with other behavioral and psychological symptoms.
Methods: A consecutive series of 302 AD patients registered in a dementia clinic were investigated in this study. All patients met the criteria of the National Institute of Neurological Disorders and Stroke–Alzheimer's Disease and Related Disorders Association for probable AD. The rates of depression were determined according to the criteria of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders for major depression (DSM-IV), the International Classification of Diseases-9-Clinical Modification (ICD-9-CM) for neurotic depression, the depression subscale of the Neuropsychiatric Inventory (NPI), and the NIMH-dAD criteria. Depression severity was assessed using the 17-item Hamilton Depression Rating Scale. The rates of depression determined by the NIMH-dAD criteria were compared with the rates derived from each of the other instruments. Other behavioral and psychological symptoms were assessed using NPI. A behavioral neurologist or a geriatric psychiatrist interviewed all the patients.
Results: Using the NIMH-dAD criteria, it was found that 90 (29.8%) of the AD patients had depression, and all depressive symptoms in NIMH-dAD were significantly higher among depressed patients. Among other depression instruments, the frequency of depression was lowest using the DSM-IV major depression criteria (9.3%) and highest with the NPI depression subscale (54%). Behavioral and psychological symptoms determined with NPI were significantly higher among depressed patients in all domains except euphoria.
Conclusions: This is the first study of depression in Taiwanese patients with AD using the NIMH-dAD criteria. Our findings suggest that comorbid depression is high in Taiwanese patients with AD. It is clinically important to note the high frequency of most behavioral and psychological symptoms among depressed AD patients.