Impact of Mild Behavioral Impairment and Mild Cognitive Impairment on Risk for Dementia

Abstract

BackgroundThere has been a shift in research to explore early indicators associated with preclinical/prodromal dementia. Recent research highlights the importance of non‐cognitive factors, such as neuropsychiatric symptoms (NPS), as articulated in criteria for mild behavioral impairment (MBI). Previous research suggests MBI is a risk factor for dementia regardless of if one is cognitively healthy or diagnosed with mild cognitive impairment (MCI). The goal of this study is to examine risk for dementia subtypes based on the presence of MBI and/or MCI.MethodSecondary data analysis of participants (n = 17,289) from the National Alzheimer’s Coordinating Center who were cognitively healthy (n = 11,770) or diagnosed with MCI (n = 5,519). Risk for dementia, Alzheimer’s disease (AD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD) were examined using Cox proportional hazard models.ResultAlmost 25% of the entire sample met the operationalized diagnostic criteria for MBI (n = 4,274). The risk for dementia almost tripled among persons with MBI and increased by almost seven‐fold if they had MCI. Among persons with MBI, the risk for FTD was six times greater and the risk for DLB and AD was three times greater, compared to those without MBI. Additionally, for participants who had MCI, the risk for DLB was six times greater, the risk for AD was over nine times greater, and the risk for FTD was almost sixteen times greater, compared to those who were cognitively healthy. There was a significant interaction found between MBI and MCI status. For cognitively healthy older adults with MBI, the risk was almost eleven times greater for FTD, whereas for older adults with MCI and MBI, the risk was three times greater for DLB.ConclusionOlder adults with MBI and MCI are at an increased risk for all types of dementia. Additionally, cognitively healthy participants with MBI are found to have a greater risk for FTD, where participants with MCI and MBI had a greater risk for DLB. These results provide support for MBI as a prodromal state of all‐cause dementia, and highlight the importance of recognizing these symptoms across the spectrum of cognitive decline.

Neuroimaging of mild behavioral impairment: A systematic review

“…The brain regions (hippocampus, parahippocampal gyrus, entorhinal cortex, and temporal lobe) identified as neural correlates of MBI 13,36,[39][40][41]43,44 (Figure 2) are known to show atrophy in the early stage of AD. 54 Tau burden in the entorhinal cortex and hippocampus has been linked to MBI in amyloid-positive NC, 17 but not in NC with an unknown amyloid status.…”

“…14,17,36,44,48,51 Second, various participants and assessments of MBI were used. Third, many studies were crosssectional, 13,14,17,36,[38][39][40][41][42][43][44][45][46][47][49][50][51] and the relationship between neural correlates of MBI and conversion from MBI to dementia was not completely clear. Fourth, statistical analysis was not possible because the study methods varied.…”

“…Magnetic resonance imaging (MRI) was performed in 18 studies 2,[11][12][13][14][36][37][38][39][40][41][42][43][44][45][46][47][48] and suggested associations of MBI with atrophy in the temporal lobe, 13,36,40,43,44 hippocampus, 13,41 parahippocampal gyrus, 13,36,39 and entorhinal cortex. 13,41 Atrophy in brain regions related to the salience network (SAN) was associated with MBI in PD.…”

“…The conversion rate to dementia ranges from 27% to 70% over a 2‐ to 15‐year period, and the types of dementia include FTD, AD, and DLB 8,11–13 . Two studies found mainly FTD, 11,12 while AD was dominant in other studies 8,13 . Interestingly, Rouse found that the hazard ratio (HR) for conversion to FTD (10.787) was higher than that for conversion to AD (3.179) and DLB (2.518) in NC with MBI 13 .…”

“…Interestingly, Rouse found that the hazard ratio (HR) for conversion to FTD (10.787) was higher than that for conversion to AD (3.179) and DLB (2.518) in NC with MBI 13 . In MCI with MBI, the HR for conversion to DLB (3.023) was the highest, followed by those for conversion to FTD (2.595) and AD (1.770) 13 …”