Amygdalar volume and psychiatric symptoms in Alzheimer's disease: an MRI analysis

Abstract

The atrophy of the amygdala does not have a direct association with the existence of neuropsychiatric symptoms. MRI volumetry of the amygdala may be relevant as a marker of dementia severity in Alzheimer's disease.

Neuropsychiatric correlates of white matter hyperintensities in Alzheimer's disease

“…The prevalence rates of BPSD in this sample of patients with AD were comparable to those reported in other studies (Hart et al , 2003). Similarly, our findings that normalized measures of whole brain volumes and hippocampal volumes correlated with performance on the MMSE are consistent with previous studies (Bigler et al , 2004; Horinek et al , 2006). Although, we were unable to detect a significant correlation between decreasing MMSE scores and WMH load, we did observe a trend in this direction, highlighting the possible cognitive impact of white matter changes in patients with AD.…”

Amygdala atrophy is prominent in early Alzheimer's disease and relates to symptom severity

“…The variability in findings is likely due to small samples, the inclusion of AD patients at varying stages of the illness (not just mild), and varying measurement techniques and anatomic boundary criteria (Barnes et al, 2006; Horinek et al, 2006; Schultz et al, 2009). The large sample sizes and similar characteristics of subjects in the present investigation, as well as the uniformity of volumetric measurement techniques, allow for a more definitive comparison of amygdala and hippocampal atrophy, and indicate that both of these MTL structures are similarly and consistently affected in the mildest clinical stages of AD dementia.…”

“…Several studies have reported on the relation between amygdala and measures of global cognitive functioning such as the MMSE (Basso et al, 2006; Cuenod et al, 1993; Deweer et al, 1995; Horinek et al, 2006; Laakso et al, 1995) and the CDR (Jack et al, 1997; Mizuno et al, 2000) in AD and its prodromal phase (mild cognitive impairment)(Kovacevic et al, 2009). Since the level of hippocampal atrophy has been shown in many studies to be strongly and consistently related to the severity of impairment in AD, and since the level of amygdala atrophy is correlated with that of the hippocampus, it would be of interest to know which explains the most variance in impairment and to what degree the other explains additional, unique variance.…”

“…First, across the 13 published studies of amygdala atrophy in AD, findings regarding the magnitude of atrophy have been very inconsistent, with reports of atrophy ranging from 15% to 41% compared to older controls (OC). Furthermore, it is unclear whether the magnitude of amygdala atrophy is greater than (Basso et al, 2006; Cuenod et al, 1993; Krasuski et al, 1998; Lehericy et al, 1994; Mori et al, 1997), less than (Callen et al, 2001; Farrow et al, 2007; Horinek et al, 2006; Jack et al, 1997), or similar to (Barnes et al, 2006; Killiany et al, 1993; Mizuno et al, 2000; Schultz et al, 2009) that of the hippocampus. Given the substantial variability in the frequency and types of socioaffective symptoms in AD, it seems reasonable to hypothesize that the amygdala would be more variably affected within a sample of AD patients than the hippocampus.…”

“…Finally, although behavioral (psychiatric) symptoms are a major contributor to patient-family dysfunction and distress in AD, there has been surprisingly little effort to investigate whether amygdala atrophy relates to this domain of symptoms. The only study to specifically examine the relation between amygdala atrophy and psychiatric symptoms in mild AD reported no relationship (Horinek et al, 2006). …”