Risk Factors for Early and Late Onset Depression and Subsequent Risk for Alzheimer\u27s Disease and Related Dementias in an Older Adult Population

The Cache County Study on Memory in Aging (CCSMA) was a research study that followed 5092 participants aged 65 or older over the course of 12 years, examining risk and protective factors for dementia. One of these factors was depression history, which has evidence for a connection with dementia, such that those with a history of depression are more likely to develop dementia later in life. However, the existing literature has yet to examine sex differences, genetic and psychosocial factors that contribute to earlier or later onset of depression and how these factors in turn might later increase risk for dementia. The current research contained two related studies. The fist study looked at how several life events, such as death of a spouse, chronic conditions, such as having diabetes, and genetic factors, such as the presence and of certain genes related to brain derived neurotrophic factor (BDNF), related to depression in early life and late life. The second study looked at how depression in early life and late life related to risk for dementia. The results of these studies showed that certain life events reliably led to depression in early life and late life for males and females, specifically death of a spouse. In late life depression, death of a mother (males only), death of a spouse, death of a child, hospitalizations of self and family and corticosteroid use (females only) were associated with increased risk of late life depression. Chronic pain conditions and number of vascular health conditions were associated with reduced likelihood of having late life depression for both males and females. Further, the presence of some BDNF-related genes changed the relationship of stressful life events and depression. Finally, late life depression was associated with increased risk of dementia only in males and having both early and late life depression was associated with reduced likelihood of having dementia among females. These results provide evidence that early identification of depression and awareness of risk factors for depression is important, particularly as history of depression may increase risk for dementia among males