Patients with amyotrophic lateral sclerosis (ALS) may have problems recognizing emotions in other people, even though they do not have other cognitive or behavioral problems. This inability is linked to microscopic changes in brain anatomy in regions linked to emotional processing, and resembles changes seen in patients with some types of frontotemporal dementia.
The study, “Microstructural Correlates of Emotional Attribution Impairment in Non-Demented Patients with Amyotrophic Lateral Sclerosis,” published in the journal PLOS ONE, underscores that these changes support the notion that brain changes seen in ALS can be viewed as different levels along a continuum of changes linking ALS with frontotemporal dementia — another feared degenerative brain condition.
About half of all who develop ALS have symptoms not related to movement. These symptoms are also observed in the behavioral variant of frontotemporal dementia. Some patients only have a few of these symptoms, while about 10 to 15 percent have the full range of symptoms known as the behavioral variant of frontotemporal dementia syndrome, basically ALS and frontotemporal dementia at the same time.
Earlier studies have found that some disease mechanisms, both brain changes, and genetic factors also overlap between the two conditions. Many researchers believe the two diseases represent various manifestations of a disease spectrum.
The recognition of emotional states in others is a requirement for empathy, and earlier studies have shown that both ALS and frontotemporal dementia patients have changes in their brain anatomy visible to the naked eye. Researchers at the Vita-Salute San Raffaele University in Italy now assessed whether ALS patients without dementia also had microscopic brain changes in key brain regions.
The study recruited 13 patients who had either been diagnosed or had suspected ALS, and 14 healthy people. Before the experiments, all ALS patients were screened for cognitive and behavioral symptoms, including language, memory, and executive functions.
Researchers identified two patients with problems in executive functions and two patients with behavioral problems, such as apathy, irritability, and loss of self-control. The remaining nine patients (70 percent) were considered “pure” ALS patients.
All participants had their brains scanned using an MRI method called Diffusion Tensor Imaging, measuring the microscopic features of the brain’s white matter. During the brain scans, participants performed two tasks to test whether they could recognize the emotional state or intentions of another person.
Compared to healthy people, patients with ALS had more problems in understanding the emotions of others. And when researchers looked only at the nine patients without apparent behavioral and cognitive problems, a lower ability to recognize emotions was evident. The recognition of intentions was not impaired, however.
The severity of the problems could also be linked to measures of microscopic changes in several brain areas linked to emotional processing, showing that problems in identifying emotions may occur in ALS patients even without other cognitive or behavioral problems.