Lifetime symptoms of depression in Alzheimer's disease.

INTRODUCTION: Depression is common in Alzheimer's disease (AD). The symptomatology of depression in dementia may differ from depression alone. Consequently, the reports on lifetime depressive symptoms were compared in AD patients and age-matched non-demented participants. METHODS: Seventy-six AD patients, 109 elderly from the general population and their 189 siblings were examined using the Composite International Diagnostic Interview (CIDI). The presence of individual lifetime depressive symptoms was compared between 76 AD patients, 29 AD patients with comorbid depression, and different control groups using chi(2) statistics and logistic regression analysis. RESULTS: Lifetime depressive symptoms were significantly more frequent in 76 AD patients than in 109 age-matched elderly from the general population. These 76 AD patients complained more about thinking and concentration disturbances, and less about depressed mood or appetite disturbance than the 298 non-demented participants matched for the lifetime presence of major depression (MD). In agreement, the 29 patients comorbid for lifetime diagnoses of AD and MD reported less about depressed mood than the 114 age-matched elderly with MD only. Feelings of worthlessness and suicidal ideas were related to the severity of cognitive decline. CONCLUSION: AD influences the reports on lifetime depressive symptoms. This may be caused by additional neurodegeneration, by an overlap of symptoms of depression and dementia or by an altered perception of mood disturbances in AD. Further studies should investigate these alternatives.