Depression has been found to occur in half of individuals given a diagnosis of Alzheimer’s disease (AD). While evidence suggests depression may be a risk factor for AD, there is also suggestion that depression is a symptom of the disease itself. The exact mechanism behind the association between depression and AD is unknown. However, it is thought the common brain changes associated with childhood trauma, including reduced development of the hippocampus and amygdala and abnormal frontotemporal electrical activity, may play a significant role.

The current study used data from 378 PREVENT participants, from West London, Oxford and Cambridge, to investigate whether midlife adults with a history of childhood trauma had greater risk of both depression, loss of hippocampal volume at midlife and in turn, cognitive performance, and risk of dementia.

It was hypothesised that childhood trauma would be associated with greater clinical depression, lower hippocampal volume and poorer cognitive performance and dementia risk at mid-life. However, while childhood trauma was associated with depression and reduced hippocampal volume, it was not related to current cognitive function or dementia risk.

The findings suggest that the aetiology of depression is different to that of dementia, and the relationship of depression to dementia risk in persons experiencing childhood trauma appears to be neither a risk factor nor a prodromal feature of the disease but that of a comorbidity which may add to brain burden. This study demonstrates that theremay be multiple routes to which depression may appear in individuals with high risk of dementia, and future research in this area should take into account the origins of variety of depression symptomatology.

Key terms and abbreviations: 

Aetiology = The cause of a disease

AD = Alzheimer’s disease

Comorbidity = The simultaneous presence of two or more diseases or conditions in one individual.