Behavioral disorders: The 'blind spot' of neurology and psychiatry.

Behavioral disorders occupy the crossroads between neurology and psychiatry, and emerging disorders, such as frontotemporal lobar degeneration of genetic origin and autoimmune encephalitis, can present with both neurological and psychiatric signs. Thus, the primary aim of this introductory article is to review frequently encountered behavioral clinical features, such as apathy and agitation, and their related syndromes, including frontal and anterior temporal syndromes. These behavioral states and their underlying etiologies are also here illustrated with clinical case reports. In addition, this review highlights the idea that in order to progress in the understanding and management of behavioral disorders, there needs to be a strong interest towards developing new forms of cooperation between neurologists, psychiatrists and neuroscientists, such as those who work at university-based hospital neuropsychiatric clinical units.

Testing the model of caudo-rostral organization of cognitive control in the human with frontal lesions.

The cascade model of cognitive control, mostly relying on functional neuroimaging studies, stipulates that the lateral frontal cortex (LFC) is organized as a cascade of executive processes involving three levels of cognitive control, implemented in distinct LFC areas from the premotor to the anterior prefrontal regions. The present experiment tested this model in patients with LFC lesions and studied the hierarchy of executive functions along the caudo-rostral axis, i.e. the respective roles of the different LFC areas in the control of behavior. Voxel-based lesion-symptom mapping and region of interest group analyses were conducted in 32 patients with focal LFC lesions who performed cognitive tasks assessing the cascade model. We first showed that three different LFC areas along the caudo-rostral axis subserved three distinct control levels, whose integrity is necessary for adaptive behavior. Second, we found that prefrontal cognitive control has an asymmetric organization: higher control processes involving more anterior prefrontal regions rely on the integrity of lower control processes in more posterior regions, while lower control processes can operate irrespective of the integrity of higher control processes. Altogether, these findings support a caudo-rostral cascade of executive processes from premotor to anterior prefrontal regions.

The Aphasia Rapid Test: an NIHSS-like aphasia test.

The Aphasia Rapid Test (ART) is a 26-point scale developed as a bedside assessment to rate aphasia severity in acute stroke patients in <3 min. We tested its inter-rater reproducibility, its sensitivity to detect changes from Day 1 to Day 8, and the predictive value of D8 ART scores on the 3-month aphasia outcome assessed with the Aphasia Handicap Score (AHS), a 0-5 "Rankin-like" score for aphasic disability. The reproducibility was tested in 91 aphasic patients within one week of stroke onset. The inter-rater concordance coefficient was 0.99 and the weighted Kappa value (κw) was 0.93. The sensitivity was tested in 70 aphasic patients by measuring changes in ART values between D1 and D8. Improvement occurred in 46 patients (66 %) and aggravation in three patients (4 %). In these patients, a logistic regression analysis showed that D8 ART was the only significant predictor of good (AHS 0-2) or poor (AHS 4-5) outcome. The ROC curves analyzes showed areas under the curve above 0.9 for good and poor outcome and revealed D8 ART best cut-off values of <12 for good and >21 for poor outcome, with more than 90 % sensitivity and 80 % specificity. The ART is a simple, rapid and reproducible language task, useful in monitoring early aphasic changes in acute stroke patients and highly predictive of the 3-month verbal communication outcome. It should be easy to adapt to other languages.