It’s often a challenge for doctors to determine whether a patient has Alzheimer’s disease or frontotemporal dementia, but a new, non-invasive method may make it a bit easier to tell the two apart. Worldwide, there’s nearly 10 million new cases of dementia every year, so distinguishing between two common types is critical.

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“Making the correct diagnosis can be difficult,” study author Dr. Barbara Borroni said in a statement. “Current methods can be expensive brain scans or invasive lumbar punctures involving a needle inserted in the spine, so it’s exciting that we may be able to make the diagnosis quickly and easily with this non-invasive procedure.”

In the preliminary study, published in the online issue of Neurology, Borroni and her colleagues studied 79 individuals with probable Alzheimer’s disease, 61 with probable frontotemporal dementia, and 32 of the same age who didn’t have any signs of dementia. In order to stimulate the patients’ nerve cells, the researchers used a method known as “transcranial magnetic stimulation” (TMS), which involves a large coil placed on the scalp. The TMS technique revealed that those with Alzheimer’s disease primarily had issues associated with one type of circuit, while individuals with frontotemporal dementia had issues with a different type of circuit.

The researchers were able to distinguish between the two types of dementia with the same accuracy as more traditional methods, such as testing spinal fluid, according to Borroni. One of the limitations of the study was that the person who controlled the TMS device knew when it was connected to a healthy person, but they weren’t told when it was connected to participants with Alzheimer’s disease or frontotemporal dementia. Also, those who were diagnosed with dementia were not confirmed of their condition by autopsy after death.

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“If our results can be replicated with larger studies, this will be very exciting,” Borroni said. “Doctors might soon be able to quickly and easily diagnose frontotemporal dementia with this non-invasive procedure. This disease unfortunately can’t be cured, but it can be managed - especially if it is caught early.”

Unlike Alzheimer’s disease, frontotemporal dementia is more likely to affect people under the age of 65. Another key difference is that people with frontotemporal dementia develop motor problems early on in their illness, according to the Memory and Aging Center at the University of California, San Francisco. One similarity between the two is that both may cause a person to appear apathetic and uninterested in hobbies they used to enjoy; however, it’s typically due to frustration with the difficulty it may cause rather than true uninterest. Globally, around 47 million people combined have Alzheimer's, frontotemporal dementia, and other types of the disease, according to the World Health Organization.

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