A study recently published in JAMA Psychiatry revisited a 120-year-old theory on “premature dementia” and has discovered similarities and some degree of overlap between schizophrenia and behavior variant frontotemporal degeneration (bvFTD).  

The similarities between the two diseases, particularly their symptomology, compelled Nikolaos Koutsouleris, MD, of Ludwig Maximilian University and Matthias Schroeter, MD, of the Max Planck Institute to compare them scientifically.  

Using machine learning and a model of neuroanatomical classifiers, Drs. Koutsouleris and Schroeter studied different cohorts of volunteers, finding that 41% of people with schizophrenia met classifying criteria for bvFTD. Similarly, the duo found that 22% of people diagnosed with major depression similarly met bvFTD criteria.  

Similar areas of the brain appeared to be affected by both diseases, including the areas responsible for empathy and attention control.  

“[BvFTD] in particular is difficult to recognize in the early stages because it occurs at a relatively young age, even here it is the most common form of dementia and is often confused with psychiatric disorders such as schizophrenia,” Koutsouleris said. “This is especially the case in sufferers with a change in the genetic material, the C9orf72 gene. This is what makes their comparison with schizophrenia so significant.” 

Some C9orf72 expansion carriers can also present with psychiatric illness such as schizophrenia or bipolar disorder, complicating the path to an FTD diagnosis. On average, it takes more than three and a half years after symptom onset to secure an FTD diagnosis, and misdiagnoses of conditions such as schizophrenia are common.

“For bvFTD, our results contribute to timely diagnosis and initiation of therapy, which is central for affected individuals and their families,” Dr. Schroeter said.