Using a combination of screening methods, it might be possible to diagnose Alzheimer’s disease earlier than ever before, according to a new study.

The study found a positron emission tomography (PET) scan could help discover amyloid proteins in the brain, which can be an important warning sign of Alzheimer’s. The use of the PET scan would come in after physicians measure levels of two certain amyloid proteins in the spinal fluid; the volumes of the two measurements usually have an inverse relationship, but when there is an unexpected or “off” measurement, a PET scan could be used to check out the amyloid levels in the brain and come to a diagnosis of dementia or Alzheimer’s.

The European study, published in the journal BRAIN, examined data from 243 people in Spain, Portugal, Germany and several Scandinavian countries. They included patients with Alzheimer’s, other kinds of dementia and 13 healthy control participants.

Study authors said that most of the patients showed the expected relationship between the two types of amyloid proteins measured (amyloid-β₄₂ and amyloid-β_42/40). But some unexpected variance was seen in the amyloid-β_42/40 in Alzheimer’s patients. They found that comparing those results with PET scan results showed a more accurate picture of the patient’s status.

“Interestingly, there was also a difference between the values measured in the brain and spinal fluid in a smaller group of patients. This may justify that, in some unclear cases, the diagnosis should include an amyloid PET scan to complement the cerebrospinal fluid sample,” said Agneta Nordberg of the Karolinska Institute in Sweden, where the study was centered, in a statement.

According to the authors, the study’s findings mean that Alzheimer’s could be detected sooner than usual, and therefore treated earlier in its progression than currently possible. Patients could start to receive treatment even before symptoms make themselves known, which could increase the chance of slowing down or reversing the disease’s degenerative march.