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Basal Forebrain Atrophy Contributes to Allocentric Navigation Impairment in Alzheimer's Disease Patients.

Kerbler GM, Nedelska Z, Fripp J, Laczó J, Vyhnalek M, Lisý J, Hamlin AS, Rose S, Hort J, Coulson EJ - Front Aging Neurosci (2015)

Bottom Line: When considering the entire sample, we found that basal forebrain volume correlated with spatial accuracy in allocentric (cued) and mixed allo/egocentric navigation tasks but not the egocentric (uncued) task, demonstrating an important role of the basal forebrain in mediating cue-based spatial navigation capacity.Regression analysis revealed that, although hippocampal volume reflected navigation performance across the entire sample, basal forebrain volume contributed to mixed allo/egocentric navigation performance in the AD group, whereas hippocampal volume did not.This suggests that atrophy of the basal forebrain contributes to aspects of navigation impairment in AD that are independent of hippocampal atrophy.

View Article: PubMed Central - PubMed

Affiliation: Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland , Brisbane, QLD , Australia.

ABSTRACT
The basal forebrain degenerates in Alzheimer's disease (AD) and this process is believed to contribute to the cognitive decline observed in AD patients. Impairment in spatial navigation is an early feature of the disease but whether basal forebrain dysfunction in AD is responsible for the impaired navigation skills of AD patients is not known. Our objective was to investigate the relationship between basal forebrain volume and performance in real space as well as computer-based navigation paradigms in an elderly cohort comprising cognitively normal controls, subjects with amnestic mild cognitive impairment and those with AD. We also tested whether basal forebrain volume could predict the participants' ability to perform allocentric- vs. egocentric-based navigation tasks. The basal forebrain volume was calculated from 1.5 T magnetic resonance imaging (MRI) scans, and navigation skills were assessed using the human analog of the Morris water maze employing allocentric, egocentric, and mixed allo/egocentric real space as well as computerized tests. When considering the entire sample, we found that basal forebrain volume correlated with spatial accuracy in allocentric (cued) and mixed allo/egocentric navigation tasks but not the egocentric (uncued) task, demonstrating an important role of the basal forebrain in mediating cue-based spatial navigation capacity. Regression analysis revealed that, although hippocampal volume reflected navigation performance across the entire sample, basal forebrain volume contributed to mixed allo/egocentric navigation performance in the AD group, whereas hippocampal volume did not. This suggests that atrophy of the basal forebrain contributes to aspects of navigation impairment in AD that are independent of hippocampal atrophy.

No MeSH data available.


Related in: MedlinePlus

Group comparison of hippocampal volumes between NC, aMCI, and AD groups. There was a significant reduction of hippocampal volume in the aMCI and AD groups compared to the NC group. The hippocampal volume of the AD group was not significantly different from that of the aMCI group. Whiskers represent min/max values except for data points (circles) more than 1.5 interquartile ranges away from the 75th percentile. ***p < 0.001
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Figure 3: Group comparison of hippocampal volumes between NC, aMCI, and AD groups. There was a significant reduction of hippocampal volume in the aMCI and AD groups compared to the NC group. The hippocampal volume of the AD group was not significantly different from that of the aMCI group. Whiskers represent min/max values except for data points (circles) more than 1.5 interquartile ranges away from the 75th percentile. ***p < 0.001

Mentions: In order to compare the basal forebrain integrity between clinical groups, we first calculated the basal forebrain volume of the whole structure, as well as the anterior and the posterior regions. These volumes were then corrected for age, education, and gender, and subsequently compared between the NC, aMCI, and AD groups, as well as being correlated to the hippocampal volume. Group comparisons revealed that the mean whole (Figure 2A; p = 0.032), as well as the anterior (Figure 2B; p = 0.044), but not the posterior (Figure 2C) basal forebrain volumes were significantly reduced in aMCI subjects compared to NC. Hippocampal volumes were significantly reduced in the aMCI and AD subject groups (Figure 3). Although we and other groups have reported significant reductions in BF volumes for AD groups previously (Grothe et al., 2011; Kerbler et al., 2014), this was not the case for the current cohort. No other significant differences in mean basal forebrain volume were found between diagnostic groups, perhaps due to the small group sizes (Table 2). As found previously (Kerbler et al., 2014), the whole (p < 0.001), anterior (p < 0.001), and posterior (p < 0.001) basal forebrain volumes were highly correlated to the hippocampal volume.


Basal Forebrain Atrophy Contributes to Allocentric Navigation Impairment in Alzheimer's Disease Patients.

Kerbler GM, Nedelska Z, Fripp J, Laczó J, Vyhnalek M, Lisý J, Hamlin AS, Rose S, Hort J, Coulson EJ - Front Aging Neurosci (2015)

Group comparison of hippocampal volumes between NC, aMCI, and AD groups. There was a significant reduction of hippocampal volume in the aMCI and AD groups compared to the NC group. The hippocampal volume of the AD group was not significantly different from that of the aMCI group. Whiskers represent min/max values except for data points (circles) more than 1.5 interquartile ranges away from the 75th percentile. ***p < 0.001
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Related In: Results  -  Collection

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Figure 3: Group comparison of hippocampal volumes between NC, aMCI, and AD groups. There was a significant reduction of hippocampal volume in the aMCI and AD groups compared to the NC group. The hippocampal volume of the AD group was not significantly different from that of the aMCI group. Whiskers represent min/max values except for data points (circles) more than 1.5 interquartile ranges away from the 75th percentile. ***p < 0.001
Mentions: In order to compare the basal forebrain integrity between clinical groups, we first calculated the basal forebrain volume of the whole structure, as well as the anterior and the posterior regions. These volumes were then corrected for age, education, and gender, and subsequently compared between the NC, aMCI, and AD groups, as well as being correlated to the hippocampal volume. Group comparisons revealed that the mean whole (Figure 2A; p = 0.032), as well as the anterior (Figure 2B; p = 0.044), but not the posterior (Figure 2C) basal forebrain volumes were significantly reduced in aMCI subjects compared to NC. Hippocampal volumes were significantly reduced in the aMCI and AD subject groups (Figure 3). Although we and other groups have reported significant reductions in BF volumes for AD groups previously (Grothe et al., 2011; Kerbler et al., 2014), this was not the case for the current cohort. No other significant differences in mean basal forebrain volume were found between diagnostic groups, perhaps due to the small group sizes (Table 2). As found previously (Kerbler et al., 2014), the whole (p < 0.001), anterior (p < 0.001), and posterior (p < 0.001) basal forebrain volumes were highly correlated to the hippocampal volume.

Bottom Line: When considering the entire sample, we found that basal forebrain volume correlated with spatial accuracy in allocentric (cued) and mixed allo/egocentric navigation tasks but not the egocentric (uncued) task, demonstrating an important role of the basal forebrain in mediating cue-based spatial navigation capacity.Regression analysis revealed that, although hippocampal volume reflected navigation performance across the entire sample, basal forebrain volume contributed to mixed allo/egocentric navigation performance in the AD group, whereas hippocampal volume did not.This suggests that atrophy of the basal forebrain contributes to aspects of navigation impairment in AD that are independent of hippocampal atrophy.

View Article: PubMed Central - PubMed

Affiliation: Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland , Brisbane, QLD , Australia.

ABSTRACT
The basal forebrain degenerates in Alzheimer's disease (AD) and this process is believed to contribute to the cognitive decline observed in AD patients. Impairment in spatial navigation is an early feature of the disease but whether basal forebrain dysfunction in AD is responsible for the impaired navigation skills of AD patients is not known. Our objective was to investigate the relationship between basal forebrain volume and performance in real space as well as computer-based navigation paradigms in an elderly cohort comprising cognitively normal controls, subjects with amnestic mild cognitive impairment and those with AD. We also tested whether basal forebrain volume could predict the participants' ability to perform allocentric- vs. egocentric-based navigation tasks. The basal forebrain volume was calculated from 1.5 T magnetic resonance imaging (MRI) scans, and navigation skills were assessed using the human analog of the Morris water maze employing allocentric, egocentric, and mixed allo/egocentric real space as well as computerized tests. When considering the entire sample, we found that basal forebrain volume correlated with spatial accuracy in allocentric (cued) and mixed allo/egocentric navigation tasks but not the egocentric (uncued) task, demonstrating an important role of the basal forebrain in mediating cue-based spatial navigation capacity. Regression analysis revealed that, although hippocampal volume reflected navigation performance across the entire sample, basal forebrain volume contributed to mixed allo/egocentric navigation performance in the AD group, whereas hippocampal volume did not. This suggests that atrophy of the basal forebrain contributes to aspects of navigation impairment in AD that are independent of hippocampal atrophy.

No MeSH data available.


Related in: MedlinePlus