Among the many clinical decisions that psychiatrists must make, assessment of a patient's risk of committing suicide is definitely among the most important, complex, and demanding. When reviewing his clinical experience, one of the authors observed that successful predictions of suicidality were often based on the patient's voice independent of content. The voices of suicidal patients judged to be high-risk near-term exhibited unique qualities, which distinguished them from nonsuicidal patients. We investigated the discriminating power of two excitation-based speech parameters, vocal jitter and glottal flow spectrum, for distinguishing among high-risk near-term suicidal, major depressed, and nonsuicidal patients. Our sample consisted of ten high-risk near-term suicidal patients, ten major depressed patients, and ten nondepressed control subjects. As a result of two sample statistical analyses, mean vocal jitter was found to be a significant discriminator only between suicidal and nondepressed control groups (p < 0.05). The slope of the glottal flow spectrum, on the other hand, was a significant discriminator between all three groups (p < 0.05). A maximum likelihood classifier, developed by combining the a posteriori probabilities of these two features, yielded correct classification scores of 85% between near-term suicidal patients and nondepressed controls, 90% between depressed patients and nondepressed controls, and 75% between near-term suicidal patients and depressed patients. These preliminary classification results support the hypothesized link between phonation and near-term suicidal risk. However, validation of the proposed measures on a larger sample size is necessary.
Objective
Newborns requiring hospitalisation frequently undergo painful procedures. Prevention of pain in infants is of prime concern because of adverse associations with physiological and neurological development. However, pain mitigation is currently guided by behavioural observation assessments that have not been validated against direct evidence of pain processing in the brain. The aim of this study was to determine whether cry presence or amplitude is a valid indicator of pain processing in newborns.
Design
Prospective observational cohort.
Setting
Newborn nursery.
Patients
Healthy infants born at >37 weeks and <42 weeks gestation.
Interventions
We prospectively studied newborn cortical responses to light touch, cold and heel stick, and the amplitude of associated infant vocalisations using our previously published paradigms of time-locked electroencephalogram (EEG) with simultaneous audio recordings.
Results
Latencies of cortical peak responses to each of the three stimuli type were significantly different from each other. Of 54 infants, 13 (24%), 19 (35%) and 35 (65%) had cries in response to light touch, cold and heel stick, respectively. Cry in response to non-painful stimuli did not predict cry in response to heel stick. All infants with EEG data had measurable pain responses to heel stick, whether they cried or not. There was no association between presence or amplitude of cries and cortical nociceptive amplitudes.
Conclusions
In newborns with distinct brain responses to light touch, cold and pain, cry presence or amplitude characteristics do not provide adequate behavioural markers of pain signalling in the brain. New bedside assessments of newborn pain may need to be developed using brain-based methodologies as benchmarks in order to provide optimal pain mitigation.
As a result of two-sample ML classification analyses, first four mel-cepstral coefficients yielded exceptional classification performance with correct classification scores of 80% between near-term suicidal patients and non-depressed controls, 75% between depressed patients and non-depressed controls, and 80% between near-term suicidal patients and depressed patients.
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