Depression May Mask Early Cognitive Decline

Key TakeawaysDistinguishing between depression and early-stage dementia is not always easy during the initial evaluation, and according to a recent literature review, the key lies in long-term follow-up.Early detection of cognitive impairment — which is frequently associated with depression in older adults — is a critical factor in prognosis, and general practitioners play a decisive role in this process.To ensure that early-stage neurodegenerative diseases are not overlooked, a US research team is calling for routine assessment of cognitive function whenever depression is diagnosed or suspected.Cognitive impairment and depression are common conditions among older adults; they influence one another and are linked by shared pathophysiological mechanisms. According to a recent literature review, depression is found in 30%-50% of individuals with Alzheimer’s disease, and the prevalence is even higher among those with Lewy body dementia or vascular dementia. The diagnosis is not always straightforward during the initial evaluation in primary care as depression can present alternately as a risk factor, a prodrome, or a differential diagnosis for mild cognitive impairment or early-stage dementia. Only standardized longitudinal monitoring of mood and cognitive function, including use of the Montreal Cognitive Assessment in collaboration with a neurologist, can help clarify the clinical picture. A major depressive episode can lead to reversible impairments in memory, attention, and executive functions. In contrast, a progressive cognitive decline observed over several months despite improvement in the depressive episode raises suspicion of an underlying neurodegenerative disease.Early Detection and PrognosisThe primary care physician is on the front lines when it comes to identifying cognitive impairments and influencing prognosis. Early detection improves patient care through faster access to both treatments and nonpharmacologic interventions, as well as through management of modifiable risk factors and better planning of care and life goals. More broadly, early detection is also associated with a reduction in clinical and social impact, both in terms of hospitalizations and falls and in terms of the burden on caregivers. Conversely, the later the detection, the more likely patients are to enter the care pathway at an advanced stage, with a loss of independence already established.Systematic screening of at-risk individuals — including those older than 55 years, patients taking multiple medications, and those reporting subjective memory complaints — could support earlier detection and allow clinicians to adjust treatment, including psychotropic drugs, anticholinergics, and other contributors to polypharmacy, in an effort to prevent further cognitive decline. Depression and Cognitive ImpairmentA systematic review of nearly 200 studies underscores the significant role comorbidities play in the relationship between depression and cognitive decline. Major depressive episodes are linked to a higher risk of developing or worsening a range of conditions, particularly neurodegenerative diseases such as Alzheimer’s and Parkinson’s, as well as cardiovascular disease, diabetes, and metabolic disorders.More recently, an American study conducted in primary care settings among individuals aged 55 and older went even further in demonstrating the intertwining of these two conditions. It shows that depression and cognitive impairments frequently coexist in this older population. Furthermore, depression appears to be closely associated with the presence of preexisting, undetected cognitive impairments, and the severity of these impairments increases with the severity of the depression. Consequently, the authors call for the systematic assessment of cognitive function whenever depression is diagnosed or suspected, as well as for screening for depression whenever cognitive impairments have been identified.This story was translated from Univadis France, part of the Medscape Professional Network.