A group of common drugs used to treat allergies and other chronic health issues increase the risk of Alzheimers and dementia, according to a new study by the University of Indiana School of Medicine. The study also found that these drugs reduce the overall size of the brain as well as its metabolism if taken regularly. The drugs, known collectively as anticholinergics, are commonly prescribed for allergies, insomnia, hypertension, cardiac problems, and depression among others. Some of the most well-known brands in the US include Xanax, Zyrtec, Valium, Wellbutrin, Benadryl, Dramamine, Paxil, and Histex. You can see a comprehensive list of anticholinergic drugs implicated in this study by clicking here. This class of drugs blocks acetylcholine in the brain, an important neurotransmitter vital to normal brain function. In people with Alzheimers, there is always a lack of this neurotransmitter and, according to this study and others, these drugs worsen the condition or can provoke it.