Smith, Joshua R.

Transcranial magnetic stimulation can provide noninvasive measures of cortical excitability and plasticity, but relationships between these measures and clinically observable features of autism are not fully characterized. Nineteen autistic participants aged 15 to 40 years were included in the analysis of a left primary motor cortex continuous theta-burst stimulation (cTBS) biomarker protocol. Motor evoked potentials were measured at baseline and at seven assessments from 5 to 60 min after stimulation. Linear mixed-effects models evaluated whether clinical measures moderated the post-stimulation motor evoked potential log-response ratio over time. Aberrant Behavior Checklist (ABC) and Attenuated Behavior Questionnaire (ABQ) analyses were restricted to the same 15 participants with caregiver-informant assessments. Catatonia severity, social impairment, ABQ Motor Total, ABQ Total, and cognitive ability did not significantly moderate the post-stimulation response. ABC Inappropriate Speech was associated with progressively greater post-stimulation facilitation (standardized Time-by-Inappropriate Speech interaction: beta = +0.688, SE = 0.210, 95% CI +0.276 to +1.099; Holm-adjusted P = .008 across eight informant-rated models). Two individual speech-related items ("Talks excessively" and "Talks to self loudly") survived false-discovery-rate correction. An exploratory eight-item ABC phenotype showed a large descriptive in-sample association (beta = +0.904, SE = 0.200, P less than .001) and directionally positive held-out performance. However, full-pipeline permutation tests were nonsignificant for both Pearson (r = .357, two-sided empirical P = .360) and Spearman correlations (rho = .446, two-sided empirical P = .261). Caregiver-rated inappropriate speech may be associated with altered post-cTBS motor cortical facilitation in autism. The candidate phenotype remains hypothesis-generating and requires independent validation.

Introduction: An elevated blood pressure (mean arterial pressure, MAP) response to exercise is an independent predictor of hypertension (HTN) development. HTN is highly prevalent in postmenopausal females. Postmenopausal, compared to premenopausal, females have a higher MAP at rest and during exercise primarily due to higher systemic vascular resistance (SVR). Studies using small muscle mass exercise have suggested that postmenopausal females have augmented increases in MAP from rest to exercise. However, it is unclear if postmenopausal females have augmented MAP responses from rest to exercise during whole-body exercise. Hypothesis: We hypothesized that postmenopausal females would have greater increases in MAP and smaller decreases in SVR from rest to peak exercise than premenopausal females. Methods: Normotensive premenopausal (n=16; age: 30±7 yrs; BMI: 23±4 kg/m 2 ) and postmenopausal (n=14; age: 57±7 yrs; BMI: 27±4 kg/m 2 ) female participants performed an incremental cycling test until task failure. Blood pressure was measured by manual sphygmomanometry, cardiac output (Q) via open-circuit acetylene wash-in technique, and SVR was calculated. Data are reported at rest and peak oxygen uptake (VO 2 ). Data are also reported as % change from rest to VO 2 peak. Results: Postmenopausal females had higher MAP and SVR at rest and at VO 2 peak than premenopausal females (all, p<0.05). Postmenopausal, compared to premenopausal, females had lower Q at VO 2 peak commensurate with the lower achieved VO 2 peak (p<0.01). Resting MAP was positively related to MAP at VO 2 peak in postmenopausal females (r=0.85, p<0.01), but not premenopausal females (p=0.22). % change in MAP from rest to VO 2 peak was not different between groups (Post: 18±8 vs. Pre: 18±9%) (p=0.94). However, postmenopausal females had smaller % decreases in SVR from rest to VO 2 peak (Post: -44±7 vs. Pre: -54±8%) and smaller % increases in Q compared to premenopausal females (Post: 113±31 vs. Pre: 162±50%) (both, p<0.01). Conclusion: Our findings indicate that postmenopausal and premenopausal females have similar increases in MAP from rest to VO 2 peak; however, the mechanisms contributing to the MAP response differed by menopausal status. Postmenopausal females relied on smaller decreases in SVR, whereas premenopausal females had greater increases in Q. These findings provide important insight into the mechanisms contributing to the clinically relevant higher MAP response during exercise in postmenopausal females.