Affiliations: [a] Otto-von-Guericke University Magdeburg, Department of Neurology, Magdeburg, Germany | [b] University of Ulm, Gerontopsychiatry, Ulm, Germany | [c] University of Tuebingen, Eye Clinic, Tuebingen, Germany | [d] German Center for Neurodegenerative Diseases (DZNE) Magdeburg, Germany
Correspondence:
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Correspondence to: Daniel M. Bittner, MD, Otto-von-Guericke University Magdeburg, Department of Neurology, Leipziger Str. 44, 39120 Magdeburg, Germany. Tel.: +49 391 6724555; Fax: +49 391 6724526; E-mail: daniel.bittner@med.ovgu.de.
Abstract: It was investigated whether alterations of the pupil's light reflex might reflect Alzheimer's disease (AD) pathology. Changes in the pupil's system might be expected due to AD pathology present in the oculomotor system of the Edinger-Westphal nucleus, and a cholinergic deficit caused by degeneration of the nucleus basalis Meynert. A rather new method of repetitive light stimulation was applied assessing variations in pupil size, latency, and amplitude over time. We analyzed 44 healthy controls, 42 subjects with mild cognitive impairment (MCI), and 66 AD patients. AD and MCI showed a less pronounced pupil size decrease and amplitude increase over time than controls. A higher MMSE was associated with a higher increase of relative amplitude and greater decrease of latency in AD and MCI, and absolute amplitude increase in AD alone. Pupil size increase correlated with cerebrospinal fluid markers in AD. Summarized pupil light reflex is not stable under repetitive stimulation, but changes systematically and less pronounced in AD and MCI. Thus repetitive stimulation of the pupil's response potentially indicates AD pathology.
