Lidocaine Ineffectiveness Suggests New Psychopharmacology Drug Target.

Objectives: The mechanism of many neuropsychiatric disorders remains unknown, but the ineffectiveness of the sodium channel blocker lidocaine has been suggested to be a biomarker for Attention Deficit Hyperactivity Disorder (ADHD) and a severe form of Premenstrual Syndrome (PMS) that is considered psychiatric. We conducted single-arm double-blind clinical trials to test whether lidocaine ineffectiveness can be used as a biomarker to identify people with these conditions and provide a clue as to the molecular mechanism and potential psychopharmacological intervention. Experimental Design: We developed a noninvasive taste test for lidocaine ineffectiveness, validated by comparing lidocaine injections to pain testing in 12 subjects, and assessed it in individuals with ADHD and PMS. Principal Observations: Lidocaine ineffectiveness had a strong association in women with ADHD + PMS in a sample of 53 subjects and controls (p < 0.001). Conclusions: These results suggest the possibility of the biological understanding of the combination of ADHD and PMS that is characteristic of the psychiatric disorder Premenstrual Dysphoric Disorder (PMDD). These results and comparison to family pedigrees of a neuromuscular channelopathy with overlapping symptoms suggest the possibility that the clinical phenotype in PMDD is produced by sensory overstimulation, and amenable to molecular understanding and treatment.

The underrecognized epilepsy spectrum: the effects of levetiracetam on neuropsychological functioning in relation to subclinical spike production.

The purpose of this prospective, open-label pilot study was to determine whether treatment with levetiracetam improves neuropsychological functioning in children and adolescents who have evidence of subclinical spike production associated with attention and learning difficulties. Six participants (mean age 9.8 years) were treated with levetiracetam up to 40 mg/kg per day and evaluated using neuropsychological (Wide Range Assessment of Memory and Learning, Second Edition), academic (Wechsler Individual Achievement Test, Second Edition, Abbreviated), and electroencephalographic assessments at baseline and after 10 weeks of treatment. Statistically significant improvements on indexes of the Wide Range Assessment of Memory and Learning, Second Edition were observed in 4 participants after 10 weeks. No statistically significant differences were observed for the Wechsler Individual Achievement Test, Second Edition, Abbreviated. Concomitant spike suppression was observed. Levetiracetam was generally well tolerated. A subset of patients exists with attention and learning problems that have associated aberrant cortical electrical activity without clinical seizures and associated neuropsychological deficits that may improve after treatment with levetiracetam.