*Correspondence:
This article was submitted to Cardiovascular and Smooth Muscle Pharmacology, a section of the journal Frontiers in Pharmacology.
Edited by: Suren Soghomonyan, The Ohio State University Wexner Medical Center, USA
Reviewed by: Suren Soghomonyan, The Ohio State University Wexner Medical Center, USA; Nicoleta Stoicea, Ohio State University Wexner Medical Center, USA; Emmett Whitaker, Nationwide Children's Hospital, USA
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The excellent review article published in
We believe a cautionary note is required before granting unrestricted endorsement to this treatment. In our experience, the use of scopolamine in the elderly may trigger episodes of amnestic delirium. The following case exemplifies the effect of transdermal scopolamine for prevention of motion sickness during a vacation ship cruise by a previously normal elderly woman.
A healthy, young-looking, intelligent and cheerful 80-year-old woman was evaluated at the Houston Methodist Hospital Memory Clinic because of an episode of “scopolamine intoxication” that occurred on November 12, 2010. She flew from Texas to Hawaii and prior to boarding a cruise ship applied a post-auricular transdermal scopolamine patch to prevent seasickness. Her last memories of the vacation include arriving to Hawaii and boarding the cruise ship. She has no recollection after becoming confused, delirious, agitated, and experiencing visual hallucinations. Because of her markedly altered mental status she was disembarked, admitted to a local hospital in Hawaii and eventually flown back to Texas 5 days later.
On November 30, 2010 her neurological and neuropsychological evaluation was consistent with Mild Cognitive Impairment - Amnestic type. A 2-deoxy-2-(18F)fluoro-D-glucose (FDG) positron emission tomography (PET) brain scan showed markedly increased tracer uptake in the basal ganglia bilaterally (Figure
In our experience, scopolamine-induced amnestic delirium in the elderly is not exceptional. Seo et al. (
The transdermal scopolamine patch applied to the post-auricular area contains 1.5 mg of scopolamine; the system releases
We hypothesize that the CNS cholinergic blocking effect of scopolamine induces a “cholinergic stress test” resulting in amnestic delirium in elderly patients who have low central cholinergic reserves as a result of age, subclinical Alzheimer's disease, or vascular lesions affecting the cholinergic pathways in the periventricular white matter. It is well demonstrated that the elderly are more sensitive to the cognitive effects of scopolamine than young individuals, probably due to central cholinergic system deficits associated with aging (Flicker et al.,
The effects of acute muscarinic blockade on brain glucose metabolism have not been well studied, but we found a striking and reversible hypermetabolism of the basal ganglia, a very unusual finding on PET imaging. The mechanism of the effect is far from understood, but muscarinic cholinergic synapses exert powerful and complex effects on neurotransmission in the basal ganglia, with muscarinic receptors mediating a wide variety of excitatory and inhibitory effects in both the direct and indirect pathways (reviewed by Benarroch,
In summary, we believe that the transdermal scopolamine patch for prevention of PONV or motion sickness should be used with caution in most elderly patients. This group includes those with a history of glaucoma or urinary problems. Scopolamine should be avoided completely in subjects with a diagnosis of Mild Cognitive Impairment or when the patient's relatives acknowledge the occurrence of age-related memory loss.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Doctor Ronald E. Fisher, Baylor College of Medicine, provided the interpretation of the FDG-PET scans.