Abstract
BackgroundThe causes of behavioral and psychological symptoms of dementia (BPSD) vary according to the dementia subtype and associated neuropathology. The present study aimed to (i) compare BPSD between patients with subcortical ischemic vascular disease (SIVD) and Alzheimer’s disease (AD) across stages, and (ii) explore the associations with diffusion tensor imaging (DTI) in the corpus callosum (CC) and other major fibers.MethodsTwenty-four patients with SIVD and 32 with AD were recruited. Four domains of the Neuropsychiatric Inventory (NPI) (hyperactivity, psychosis, affective, and apathy) and two DTI parameters [fractional anisotropy (FA) and mean diffusivity (MD)] within the genu, body (BCC), and splenium (SCC) of the CC and other major fibers were assessed.ResultsOverall, the patients with clinical dementia rating (CDR) 1 ~ 2 had higher scores in apathy domain than those with CDR0.5. Among those with CDR1 ~ 2, SIVD had higher scores in apathy domain than AD. MD values in the BCC/SCC were positively correlated with total NPI score and psychosis, hyperactivity, and apathy domains. FA values in the SCC were inversely correlated with total NPI score and psychosis domain. The correlations were modified by age, the CASI, and CDR scores. Stepwise linear regression models suggested that FA value within the left superior longitudinal fasciculus predicted the hyperactivity domain. MD value within the SCC/left uncinate fasciculus and FA value within the GCC/left forceps major predicted the psychosis domain. MD value within the right superior longitudinal fasciculus and CDR predicted the apathy domain. Further analysis suggested distinct patterns of regression models between SIVD and AD patients.ConclusionWhite matter integrity within the BCC/SCC had associations with multi-domains of BPSD. Our study also identified important roles of regions other than the CC to individual domain of BPSD, including the left superior longitudinal fasciculus to the hyperactivity domain, the left uncinate fasciculus/forceps major to the psychosis domain, and the right superior longitudinal fasciculus to the apathy domain. The neuronal substrates in predicting BPSD were different between SIVD and AD patients. Of note, apathy, which was more profound in SIVD, was associated with corresponding fiber disconnection in line with dementia severity and global cognition decline.
Highlights
The causes of behavioral and psychological symptoms of dementia (BPSD) vary according to the dementia subtype and associated neuropathology
The analysis found that mean diffusivity (MD) value within the the splenium of the corpus callosum (SCC) (MD SCC) (β = 0.524, t = 4.073, p < 0.001), fractional anisotropy (FA) value within the left forceps major (FA Lfmajor) (β = 0.296, t = 2.552, p = 0.014), MD value within the left uncinate fasciculus (MD Lunc) (β = 0.312, t = 2.614, p = 0.012) and FA value within the GCC (FA GCC) (β = 0.316, t = 2.310, p = 0.025) significantly predicted its severity (R2 = 0.390, F(4,51) = 8.16, p < 0.001)
In summary, we found that both apathy and delusion were more profound in line with the severity of dementia than other psychiatric symptoms, especially in the patients with subcortical ischemic vascular disease (SIVD)
Summary
The causes of behavioral and psychological symptoms of dementia (BPSD) vary according to the dementia subtype and associated neuropathology. Patients with dementia often exhibit a combination of these symptoms and tend to present with changed behaviors at a certain stage of disease This suggests that underlying organic brain structural changes and distinct neurobiological properties may be responsible for the pathogenesis of BPSD. Studies comparing BPSD between patients with vascular dementia (VaD) and Alzheimer’s disease (AD) have reported varying results with regards to frequency [8] and according to care setting [9], or even no apparent differences [6]. This inconsistency in results may partially be explained by the fact that VaD is comprised of a group of heterogeneous pathologies. Patients with dementia with advancing age are more likely to have both AD and VaD pathology, confounding their relevant clinical presentations
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