Abstract
Objectives To characterise functional brain activity reflecting neuropsychiatric disturbances in patients with anti-N-methyl-D-aspartate receptor (anti-NMDA-R) encephalitis.
Methods 12 anti-NMDA-R encephalitis patients and 19 age and gender matched control participants completed neuropsychological tests including Hopkins Verbal Learning Test, Digit Span test, logical memory subtests 1 and 2 from the Wechler Memory Scale, National Adult Reading Test of IQ, Stroop test, Trail making tests A&B, Verbal fluency, matrix reasoning and WAS-II Vocabulary subtest. Functional Magnetic Resonance Imaging (fMRI) of brain function was undertaken in each participant while undergoing the Shifting Response Set task.
Results Significant differences in neurocognitive function were observed, with decreased function in anti-NMDA-R encephalitis patients on tests of verbal fluency (F[1,29]=6.7, p=0.15) backwards digit span recall (F[1,29]=4.9, p=0.035), Hopkins verbal learning test (F[1,29]=16.5, p<0.001) matrix reasoning test (F[1,29]=9.7, p=0.004), vocabulary (F[1,29]=16.8, p<0.001), trail making test (F[1,29]=9.0, p=0.006) and logical memory (F[1,29]=6.3, p=0.018). Factor analysis revealed these neurocognitive tests loaded onto a single factor, providing one statistical measure quantifying deficits across these domains.
Functional brain responses during shifting response set differed significantly between anti-NMDA-R encephalitis patients and matched controls. Whereas controls reduced activity within the subgenual cingulate, ventrolateral and superior frontal prefrontal cortices, activity was increased within patients.
Neural responses in the right superior parietal cortex, mid anterior cingulate cortex and right ventrolateral cortex reflected generalised neurocognitive deficits (single factor) in patients, relative to controls.
Conclusions Our findings further understanding of neural changes within anti-NMDAR encephalitis, and identify cortical regions where altered function reflects the severity of neurocognitive deficits.
