At least 15,000 more Americans have died in recent months from Alzheimer’s disease and dementia than otherwise would have, health officials believe, pointing to how the coronavirus pandemic has exacted a higher fatality toll than official numbers have shown.

Roughly 100,000 people died from Alzheimer’s and dementia from February through May, the U.S.

Although not all the extra deaths were directly caused by the coronavirus, that fatality rate is 18% higher than average for those disorders in recent years.

Some of the deaths were likely caused by Covid-19, the disease caused by the new coronavirus, but weren’t counted as such on death certificates, according to the CDC.

People with advanced Alzheimer’s and dementia are often in fragile health, dependent on steady routines and close care from family members and other caregivers but vulnerable to disruption.