Altered brain connectivity behind atypical personality traits in myotonic dystrophy?

By Reuters Staff

NEW YORK (Reuters Health) - Functional brain abnormalities may explain atypical personality traits in adults with myotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, hints new research from Italy.

"Our findings provide novel biological evidence that DM1 is a clinical condition that also involves an alteration of functional connectivity of the brain," the researchers report in JAMA Neurology, online March 24. "We speculate that these functional brain abnormalities, similarly to frank psychiatric disorders, may account for the atypical personality traits observed in patients with DM1."

Dr. Marco Bozzali from the Neuroimaging Laboratory, IRCCS Santa Lucia Foundation in Rome and colleagues studied 27 patients with genetically confirmed DM1 and 16 matched healthy control individuals. All of them underwent standard personality assessment as well as resting-state functional magnetic resonance imaging (fMRI).

This is the first study to investigate brain functional networks and their relationship with personality traits/disorders in patients with DM1, the researchers note.

In the DM1 group, they identified a "continuum of atypical personality profiles" ranging from schizotypal personality traits to paranoid personality disorder.

On fMRI, compared with controls, the DM1 group showed abnormalities in functional connectivity in the default mode network (DMN). "The main result," say the researchers, "was an increase in functional connectivity within bilateral posterior cingulate and the left parietal node. Similar findings have been observed in patients with severe psychiatric disorders, such as schizophrenia."

Indeed, in the DM1 group, these abnormalities correlated strongly with the presence of atypical personality profiles characteristic of DM1, namely schizotypal-paranoid traits.

"In schizophrenia, increased DMN connectivity has been proposed to reflect the neurobiological substrate for patients' inability to redirect resources from internal thoughts and feelings toward external stimuli," the researchers write. "These deficits make implementation of adaptive strategies in response to environmental modifications difficult for patients with schizophrenia."

"We similarly speculate that the presence of schizotypal and/or paranoid traits observed in our patients with DM1 can be associated with an over engagement of their DMN, which could eventually lead to an exaggerated focus on one's own thoughts and feelings," they say.

They team did not respond to a request for comment by press time.

SOURCE: http://bit.ly/1l7buvD

JAMA Neurol 2014.

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