Pilot Study of Reticular Activating System (RAS) in Mild Dementia

Frank Ho-yin Lai*, Eddie Hai, Catherine Chan

*Corresponding author for this work

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Clinically, the common early symptoms of dementia include memory problems, reduced concentration, behaviour changes, apathy and withdrawal, loss of ability to do everyday tasks. These cognitive functions are mediated by the reticular activating system (RAS) that is a collection of interconnected brain nuclei that regulates wakefulness, alertness and modulate behaviors. The RAS degenerates early during Alzheimer’s disease progression in association with abnormal tau build-up.

This study aimed to explore the relationship between the RAS functioning and older people with mild grade dementia. The Kendrick Object Learning Test (KOLT) is a test of recall of everyday objects after viewing for a brief period, an immediate recall of briefly perceived visual data. The Kendrick Digit Copying Test (KDCT) is a test of speed in processing and recording information. These tests suggested cortical excitation mediated by both the RAS and the hypothalamic limbic network which deteriorate in older people with mild grade dementia.

In this pilot study, 25 demented patients with mild grade dementia and 20 participants with known depression were recruited. They are matched in age (mean age 72 with sd 4.89) and shared similar demographic background. The participants were tested with the Kendrick Object Learning Test (KOLT) andthe Kendrick Digit Copying Test (KDCT). To observe the short term longitudinal change of their RAS functioning, these tests were administered again 4 weeks following baseline. With regular day activity treatment, the depressive group showed improvement in KOLT (p < 0.1), but not on KDCT (p = .82).However, in the dementia group, there were no significant difference noted in both KOLT and KDCT (p < 0.5).

The present findings echo some findings of RAS does not function properly as in the older people with dementia. The reticular system is not compromised in group of depressive participants, there- would be improvement in object learning, but no significant difference on speed in processing and recording information as measured by speed-performance tests (KDCT). Proper and targeted rehabilitation training sand care giving techniques could be arranged in meeting the specific patients’ needs.
Original languageEnglish
Article numbere071293
Number of pages1
JournalAlzheimer's & Dementia: the journal of the Alzheimer's Association
Issue numberS18
Early online date19 Jul 2023
Publication statusPublished - 1 Dec 2023
EventAlzheimer's Association International Conference 2023: AAIC2023 - Amsterdam, Amsterdam, Netherlands
Duration: 16 Jul 202320 Jul 2023

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