Prolonged exposure to caffeine has been linked to worsening Alzheimer’s symptoms — at least in mice, that is — by researchers in Spain.

Caffeine might heighten behavioral and psychological symptoms of dementia, including delusions, hallucinations, irritability, anxiety and depression, the study’s lead researcher noted.

Previous investigations have linked coffee to a lower risk of developing Alzheimer’s, but the Spanish team found the effects could be harmful for individuals who already have the disease.