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. 2021 Sep;36(9):1398-1406.
doi: 10.1002/gps.5540. Epub 2021 Apr 9.

Neural correlates of the impulse dyscontrol domain of mild behavioral impairment

Sascha Gill  1   2 , Meng Wang  1   3 , Pauline Mouches  1   4 , Deepthi Rajashekar  1   4 , Tolulope Sajobi  1   3 , Frank P MacMaster  1   5   6 , Eric E Smith  1   2 , Nils D Forkert  1   2   4 , Zahinoor Ismail  1   2   3   5   7 ; Alzheimer's Disease Neuroimaging Initiative
Affiliations

Neural correlates of the impulse dyscontrol domain of mild behavioral impairment

Sascha Gill et al. Int J Geriatr Psychiatry. 2021 Sep.

Abstract

Objectives: Agitation and aggression are common in dementia and pre-dementia. The dementia risk syndrome mild behavioral impairment (MBI) includes these symptoms in the impulse dyscontrol domain. However, the neural circuitry associated with impulse dyscontrol in neurodegenerative disease is not well understood. The objective of this work was to investigate if regional micro- and macro-structural brain properties were associated with impulse dyscontrol symptoms in older adults with normal cognition, mild cognitive impairment, and Alzheimer's disease (AD).

Methods: Clinical, neuropsychiatric, and T1-weighted and diffusion-tensor magnetic resonance imaging (DTI) data from 80 individuals with and 123 individuals without impulse dyscontrol were obtained from the AD Neuroimaging Initiative. Linear mixed effect models were used to assess if impulse dyscontrol was related to regional DTI and volumetric parameters.

Results: Impulse dyscontrol was present in 17% of participants with NC, 43% with MCI, and 66% with AD. Impulse dyscontrol was associated with: (1) lower fractional anisotropy (FA), and greater mean, axial, and radial diffusivity in the fornix; (2) lesser FA and greater radial diffusivity in the superior fronto-occipital fasciculus; (3) greater axial diffusivity in the cingulum; (4) greater axial and radial diffusivity in the uncinate fasciculus; (5) gray matter atrophy, specifically, lower cortical thickness in the parahippocampal gyrus.

Conclusion: Our findings provide evidence that well-established atrophy patterns of AD are prominent in the presence of impulse dyscontrol, even when disease status is controlled for, and possibly in advance of dementia. Our findings support the growing evidence for impulse dyscontrol symptoms as an early manifestation of AD.

Keywords: Alzheimer's disease; aggression; agitation; geriatric psychiatry; impulse dyscontrol; mild behavioral impairment.

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Conflict of interest statement

Dr. Ismail reports consultation fees and honoraria from Janssen, Lundbeck, and Otsuka, outside the submitted work; Dr. Smith reports personal fees from Alnylman Pharmaceuticals and Biogen, outside the submitted work; no other authors have financial interests with commercial interests.

SG analyzed and interpreted the data and contributed in writing the manuscript. PM, MW, DR, and TS were involved in the statistical analyses. FPM, EES, NDF, and ZI critically analyzed the results and made intellectual contributions to writing the manuscript. All authors read and approved the final manuscript.

Figures

FIGURE 1
FIGURE 1
Visual representation of diffusion tensor imaging regions analyzed in association with impulse dyscontrol symptoms (A) profile view, (B) sagittal view, (C) coronal view
FIGURE 2
FIGURE 2
Visual representation of volumetric regions analyzed in association with impulse dyscontrol symptoms (A) profile view, (B) sagittal view, (C) coronal view
See this image and copyright information in PMC

References

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