Dr. Keith Vossel, with help from researchers at the University of California San Francisco (UCSF), has found that some seizures, those that can't be seen, may be linked to Alzheimer’s disease.

These seizures were “subtle neuronal discharges during sleep that people didn’t even realize were happening and that can only be detected with sensitive tests,” Dr. Vossel said in an interview.

Vossel found 42 percent of Alzheimer’s disease patients had theses subtle neuronal discharges. Those that had these episodes showed a faster decline in their mental ability than patients who did not.