Abnormal pattern electroretinogram in Alzheimer's disease: evidence for retinal ganglion cell degeneration?

We recorded pattern-reversal electroretinograms, flash electroretinograms, pattern-reversal visual evoked potentials, and flash visual evoked potentials in 6 patients with clinically diagnosed Alzheimer's disease and 6 age- and sex-matched control subjects. The mean amplitude of the pattern-reversal electroretinogram in the Alzheimer patients was significantly less than that of the control group (p = 0.004). This anomaly of the pattern-reversal electroretinogram may be a reflection of documented axonal depletion within the optic nerve and the degeneration of retinal ganglion cells seen in Alzheimer's disease. We found Alzheimer patients to have normal pattern-reversal visual evoked potentials and flash electroretinograms, but a delayed second positive component of the flash visual evoked potential. This combination of findings may be of diagnostic import in Alzheimer's disease.