MedicalResearch.com Interview with:
Zahinoor Ismail MD FRCPC
Clinical Associate Professor,
Hotchkiss Brain Institute
University of Calgary
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Depression and depressive symptoms are common in mild cognitive impairment (MCI). Evidence suggests that depression in MCI increases the likelihood of progression from MCI to dementia, compared to non-depressed people with MCI. In the newer construct of mild behavioural impairment (MBI), which describes the relationship between later life onset of sustained and impactful neuropsychiatric symptoms and the risk of cognitive decline and dementia, depression is an important subdomain (in addition to apathy, impulse control, social cognition and psychotic symptoms). Thus, depression and depressive symptoms are a significant risk factor for cognitive, behavioural and functional outcomes in older adults who have at most mild cognitive impairment. As the importance of neuropsychiatric symptoms in older adults emerges, good prevalence estimates are required to inform clinicians and researchers as well as public health policy and decision makers.
We performed a systematic review and meta-analysis to determine the best estimate of prevalence of depression in mild cognitive impairment. We included 57 studies, representing 20,892 participants in the analysis. While we determined that the omnibus prevalence estimate was 32%, there was significant heterogeneity in this sample based on setting. In community samples, the rate was 25%, but in clinical samples this was higher at 40%. Additionally, different case ascertainment methods for depression (self report, clinician administered or caregiver report) and different MCI criteria didn’t change the prevalence estimates.
MedicalResearch.com: What should readers take away from your report?
Response: Depression and depressive symptoms are common and very important in older adults with mild cognitive impairment. Irrespective of how depression is diagnosed in this population, the presence of depressive symptoms is an important signal that requires attention and follow up.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: We have determined baseline prevalence rates of depression in mild cognitive impairment.
Longitudinal studies are required to determine the relative impact of different depressive features on progression to dementia as well as interactions and comorbidity with other neuropsychiatric symptoms, as in the MBI construct. Further imaging and biomarker studies are required to determine if depressive symptoms in MCI are a unique target for dementia progression, or if they are simply a manifestation of underlying dementia neuropathology.
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Ismail Z, Elbayoumi H, Fischer CE, Hogan DB, Millikin CP, Schweizer T, Mortby ME, Smith EE, Patten SB, Fiest KM. Prevalence of Depression in Patients With Mild Cognitive ImpairmentA Systematic Review and Meta-analysis. JAMA Psychiatry. Published online November 23, 2016. doi:10.1001/jamapsychiatry.2016.3162
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