People with Alzheimer’s disease often have other neurodegenerative conditions as well, including a less-understood disorder called frontotemporal lobar degeneration. While a precise diagnosis of FTLD has only been possible during an autopsy, recent research shows how clinicians may be able to diagnose people living with both Alzheimer’s and FTLD by evaluating neuropsychiatric symptoms.

In a study published in Neurology, researchers found that compared to patients who have either of the two types of dementia alone, having both Alzheimer’s disease and FTLD is associated with greater likelihood of having known neuropsychiatric symptoms of both diseases.

“We tend to study cognitive disorders in isolation, but people don’t usually have just Alzheimer’s by itself,” says Daliah Ross, PhD, a postdoctoral fellow in clinical neuropsychology.

The findings could have important implications for patients and their caregivers, because patients with both disorders may experience a more complex disease course, rapid decline, or unique responses to disease-modifying treatments.

“We saw that there were different neuropsychiatric symptoms if people had both pathologies, which could inform diagnosis and treatment plans,” Ross says. “The development of neuropsychiatric symptoms can be really impactful on patients and their families in terms of quality of life and resources needed. It would be helpful for patients and families to have a better sense of what to expect so they can prepare.”

FTLD involves symptoms like disinhibition and personality change that are not typically expected of Alzheimer’s patients. However, scientists have conducted little research on the combination of Alzheimer’s and FTLD. In other neurodegenerative conditions, Ross says, multiple pathologies alter the presentation of neuropsychiatric symptoms, complicating clinical care.

The findings may allow clinicians to provide more education and resources for FTLD patients and their care partners, says Edward Huey, MD, associate director of Brown’s Center for Alzheimer’s Disease Research and director of the Memory and Aging Program at Butler Hospital.

“This study shows a strong association between the amount of FTLD neuropathology and the symptoms of FTLD including personality changes, apathy, and inappropriate behaviors, all of which are more common in FTLD than in Alzheimer’s disease,” Huey says. “There aren’t currently any known disease-modifying treatments for FTLD, and we desperately need them.”