A new study from the United Kingdom found a link between commonly prescribed anticholinergic drugs and an increased risk of dementia. JAMA Internal medicine published the study 

Anticholinergics are a type of drug that help contract and relax muscles. The medicine blocks a neurotransmitter called acetylcholine that transmits messages to the nervous system. They're used to treat a wide range of diseases and conditions, and are found in many medications such as Benadryl, antipsychotics, antidepressants and Parkinson's medications. 

The study found that people aged 55 and older who took strong interscholastic medications daily for three years showed a 50% increased risk of developing dementia. 

The study also highlighted which types of anticholinergic drugs were most strongly linked to dementia. The study found potential dementia risks in antidepressants, bladder antimuscarinic drugs, drugs that treat Parkinson's and epilepsy drugs. 

Antihistamines, skeletal muscle relaxants,gastrointestinal antispasmodics, antiarrhythmics, or antimuscarinic bronchodilators were named as having no significant  risk for dementia. 

Researchers emphasized that the study is observational, and therefor a conclusion cannot be made that these drugs actually cause dementia. Patients who are taking these drugs should not stop taking them without consulting a medical professional first. 

There were also some limitations to the study. Researches adjusted for confounding variables, or outside things that could also cause dementia, such as BMI, weight, smoking status and alcohol consumption. They couldn't however, control for whether or not patients took their medication as directed, which could have affected results. While researchers found a link between antidepressant use and an increased risk of dementia, there is still debate in the medical world over whether depression is in itself a risk factor for dementia.