3). Figure 3 Bar chart illustrating left and right hippocampal volumes computed from MRI for intact hippocampi, AD without HS, bilateral HS, left-only HS, and right-only HS. Analysis of variance showed Romidepsin purchase significant group differences in hippocampal MRI volumes (P < 0.001). Post hoc comparisons showed 32% greater atrophy in bilateral HS compared with AD (P < 0.001). There were also statistically significant differences Inhibitors,research,lifescience,medical between intact versus AD and intact versus HS for both right and left hippocampi

(P < 0.001). On average, volumes for HS hippocampus were 52% and AD volumes were 30% less than intact hippocampi. As one might expect, for left-only HS, the left HV was smaller than the right (P = 0.002), and for right-only HS, the right volume was smaller than the left (P = 0.04). Inhibitors,research,lifescience,medical As noted previously in the literature (Wang et al. 2003; Lye et al. 2004), in the cases with intact hippocampi, the right hippocampus was significantly larger than the left hippocampus (P = 0.009). The right HV for right-only HS was 31.3% larger than the left HV for left-only

Inhibitors,research,lifescience,medical HS (P = 0.01), which may reflect underlying hemispheric asymmetries found in normal controls. Of interest, in right- or left-only HS cases, the MRI volumes in the contralateral and apparently uninvolved hippocampus were smaller than normal. For left-only HS cases, the right HV was significantly less than for normal controls (P = 0.0002). For right-only HS cases, there was a trend showing smaller volume of the left hippocampus compared with controls (P = 0.07). No statistically significant Inhibitors,research,lifescience,medical right versus left differences was found for either bilateral HS or AD. Discussion HS may be a dramatic finding at autopsy that often escaped clinical recognition and diagnosis during a given subject’s lifetime. In Inhibitors,research,lifescience,medical this convenience sample enriched for SIVD, AD, and normal aging, we found HS in 24.5% of autopsy cases. In our 31 cases, the laterality of HS showed significant variability: 45% were

bilateral, 32% left-sided, and 23% right-sided. The frequency of HS in our study was nearly isothipendyl double the 12% previously reported in a community-based dementia autopsy series (Leverenz et al. 2002). Compared with the literature, our sample was intentionally enriched for SIVD, however, HS was found in roughly equal proportions in AD and SIVD (24% and 29%, respectively). More likely, the higher frequency of HS in our sample reflects the systematic examination of both hippocampi throughout their rostral–caudal extent in the majority of our cases. Indeed, based on our findings, the prevalence of HS will be underestimated by at least 25% if only one cerebral hemisphere is examined. We initially defined complete HS as involvement across multiple coronal sections.