Dementia and geriatric depression: The links

Dementia and depression in later adult life share many pathophysiological, pathological, and clinical features. Late life depression defined as depression after age 65, is frequently associated with cognitive changes and memory impairments. On the other hand, dementia commonly presents with mood and behavioral changes particularly apathy and depressive symptoms. Neurodegeneration, impaired neuroprotection and increased inflammation are common pathological features of depression and dementia. Alterations in white matter (possibly due to vascular impairment), hippocampal atrophy, and abnormalities in hypothalamic-pituitary-adrenal axis and neurotransmitter disturbances are other common features of depression and dementia. This bidirectional relationship between dementia and depression in older adults makes the diagnosis of either condition challenging. Different types of dementias are associated with different degrees of depressive symptoms with different complexities. Depression itself, can lead to progression of reversible dementia to irreversible one. When diagnosing, several important points should be taken into account, including temporality of the symptoms (whether depression or dementia appeared first), using screening tools as well as excluding underlying medical illness such as thyroid disease and vitamin B12 deficiency. This review briefly discusses the clinical and pathophysiological similarities of and differences between these two conditions and explains the co-morbidity, together with diagnostic clues, in order to provide a better insight for understanding and differentiating these two disorders.