Differential diagnoses and assessment of depression in elderly patients.

Depression in the elderly contributes to decreased quality of life and increased mortality from both suicide and medical illnesses, yet it remains underdiagnosed and undertreated in these patients. Physicians should be aware of the varying presentations of depression in older adults and differentiate late-life depression from other psychiatric diagnoses. Thorough medical and cognitive assessments are necessary to determine whether late-life depression is due to underlying medical causes and neurologic diagnoses such as Alzheimer's disease or dementia. Depression rating scales, cognitive screening instruments, and structural and functional neuroimaging studies may be implemented as the situation requires. Greater recognition and more aggressive treatment of depression in older patients are needed.