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Dementia
Published in Henry J. Woodford, Essential Geriatrics, 2022
The limbic system, which lies predominantly within the medial temporal lobes, is thought to play a crucial role in the processing of memories (seeFigure 6.7). Acetylcholine, norepinephrine and serotonin pathways are affected. The cholinergic neuronal projections of the nucleus basalis of Meynert within the limbic system to the cortex are particularly impaired.
Degenerative Diseases of the Nervous System
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
James A. Mastrianni, Elizabeth A. Harris
DLB is complex and poorly understood. The features of disease are multifactorial. Motor symptoms likely result from the loss of dopamine-containing neurons within the substantia nigra, the key feature associated with PD. Cognitive dysfunction may be related to the loss of cholinergic neurons within the nucleus basalis of Meynert, as is typically present in AD. The presence of Lewy bodies in cortical layers V and VI likely impairs informational processing from neocortex to subcortical structures. Hallucinations may relate to early impairment in the parietal and occipital association cortices, which may also account for the predominance of visuospatial dysfunction in these patients compared with AD. The extreme fluctuations in alertness have not been explained.
EEG in the Diagnosis of Early Alzheimer Disease
Published in Robert E. Becker, Ezio Giacobini, Alzheimer Disease, 2020
H. Soininen, P. Riekkinen, V.J. Partanen, A. Pääkkönen, E-L. Helkala, V. Laulumaa
Though AD is associated with several neurochemical alterations, the most consistent change in brains of AD patients is the deficit of the cholinergic system (Bird et al., 1983; Davies, 1983; Rossor et al., 1986; Palmer et al., 1987). Reduction of the presynaptic cortical cholinergic markers and the loss of neurons in the nucleus basalis of Meynert have been confirmed in numerous studies (Whitehouse et al., 1981;Reinikainen et al., 1988). Both pharmacological and lesion studies suggest that the ascending cholinergic projections from the nucleus basalis to the neocortex play a major role in the regulation of brain electric activity (Vanderwolf, 1975; Steward et al., 1984; Buzsaki et al., 1988). Reduction of the cholinergic drive to the cortex with anticholinergic drugs, scopolamine or atropine, or lesions of nucleus basalis have induced EEG slowing. Thus it is interesting to find out whether there is any relationship between cholinergic markers and EEG slowing in AD. On the other hand, there is evidence supporting the contribution of the monoaminergic system to EEG activity (Vanderwolf, 1984). Interestingly, a correlation analysis between quantitative EEG variables and a cholinergic marker (AChE activity of the CSF) and CSF monoamine metabolite concentrations (homovanillic acid, HVA; 5-hydroxyindoleacetic acid, 5-HIAA; 3-methoxy-4-hydroxyphenylglycol, MHPG) of AD patients, showed a significant negative correlation between the delta power and the CSF AChE activity (r=-0.57, p<0.001, n=23) (Riekkinen et al. 1989). Monoamine metabolites did not correlate with any of the EEG parameters.
The cognitive safety of antimuscarinics in the treatment of overactive bladder
Published in Expert Opinion on Drug Safety, 2020
George Araklitis, Dudley Robinson
Patients with Alzheimer’s disease have been shown to have accumulation of amyloid in cortical neuritic plaques and walls of vessels as well as intraneuronal deposition of neurofibrillary tangles [37]. There is also damage to the microcirculation and the BBB. The deposition of amyloid-beta (Aβ) peptide around cortical vessels causes stenosis, leading to ischemia. The peptide also destroys the myocytes in the vessels leading to disruption in the control of cerebral blood flow. Furthermore, the vessels in the brain, which are innervated by cholinergic neurons of the nucleus basalis of Meynert, are damaged in Alzheimer’s disease. A study on rabbits, found that ablation of the cholinergic neurons of the nucleus basalis of Meynert, caused Aβ peptide deposition around cerebral vessels [37] although this was not the case in sham rabbits. The authors conclude that loss of cholinergic innervation was an important factor in the development of Alzheimer’s disease.
An update on the utility and safety of cholinesterase inhibitors for the treatment of Alzheimer’s disease
Published in Expert Opinion on Drug Safety, 2020
Andrea Haake, Kevin Nguyen, Lauren Friedman, Binu Chakkamparambil, George T Grossberg
Major Neurocognitive Disorders (formerly Dementias) are characterized by a decline in cognition limiting the patient’s day-to-day social and/or occupational function. AD is the most common cause of Major Neurocognitive Disorders. Due to its growing world-wide prevalence, AD is a significant cause of disability, mortality and caregiver burden . The cholinergic hypothesis suggests that atrophy and loss of cholinergic neurons especially in the nucleus basalis of Meynert is the hallmark of the pathophysiology of AD and results in cognitive and functional symptoms. Consequently pharmacotherapy, namely the use of ChEIs to increase cholinergic neuro-transmission, is currently the mainstay in the symptomatic treatment of AD.
Relationship Between Posturography, Clinical Balance and Executive Function in Parkinson´s Disease
Published in Journal of Motor Behavior, 2019
Carolina de Oliveira Souza, Mariana Callil Voos, Alessandra Ferreira Barbosa , Janini Chen, Debora Cristina Valente Francato, Matija Milosevic, Milos Popovic, Erich Talamoni Fonoff, Hsin Fen Chien, Egberto Reis Barbosa
The cholinergic system may play a pivotal role as a unifying factor in balance and cognition control. The nucleus basalis of Meynert supplies most cholinergic inputs to the cerebral cortex, modulating the hippocampus activity and cognitive frontoparietal networks (Coyle, Price, & DeLong, 1983). Moreover, the cholinergic pedunculopontine nucleus exerts a key role on both posture and attention (Mena-Segovia, Bolam, & Magill, 2004). A neuroimaging study (Rochester et al., 2012) used the short-latency afferent inhibition method to reflect cholinergic activity. It demonstrated the association between gait dysfunction, cholinergic deficiency, and attention impairment in people with PD.