PP513 - Effects of Acute Cigarette Smoking and Stimulus Type on AMLR in Younger vs. Older Adults

Abstract: Cigarette smoking is a public health concern for younger and older generations alike, with known links to hearing loss. In adult smokers, this relationship can be measured with the auditory middle latency response (AMLR) as nicotine receptors share common landmarks with central auditory neural pathways. The current study examined acute versus chronic multichannel AMLR recordings in 22 younger and older smokers across three stimuli conditions (clicks, 500 Hz, and 3000 Hz tonebursts). This session will explore results from waveform analyses and mixed model ANOVA findings. Clinical implications regarding test protocol, stimulus selection, and participant case history will be elucidated.

Summary:

Cigarette smoking among adults is a public health concern and leading cause of preventable disease. One such chronic disease is hearing loss, which has been linked to smoking, making it possible that audiology caseloads may include higher proportions of smokers. Smokers with age-related hearing loss present an interesting clinical case due to possible intertwined impacts of smoking and aging on the central auditory nervous system (CANS). Thus, audiologists may use the auditory middle latency response (AMLR) as an ideal measure for evaluating the CANS that is sensitive to both age-related changes and nicotine effects. AMLR research indicated trends for long-term (chronic) smoking effects, however less is known about short-term (acute) nicotine effects immediately following cigarette smoking. Currently, click stimuli are often selected for AMLR clinical protocols for faster test time, however, clicks may not be optimal for clients with high frequency hearing loss. Thus, the purpose of the current study is to explore acute effects of cigarette smoking on multichannel AMLR recordings considering participant age and stimulus type. 

 

Study hypotheses were: 1) Acute smoking effects will occur with higher amplitudes and shorter latencies than chronic AMLRs in younger and older smokers. 2) Stimulus type will influence acute AMLR similarly to past chronic findings, with tonebursts producing longer latencies and lower amplitudes than clicks. 3) Interaction and possible additive effects of smoking, stimulus type, and age will yield differential impacts in younger versus older smokers.  

 

A cross-sectional study design facilitated the evaluation of smoking effects in the AMLR. Waveforms were acquired from 22 participants confirmed as smokers via biochemical urine analysis. Smokers were younger (aged 19–29) or older (aged 46–71) individuals. AMLR was acquired with three counterbalanced stimuli (clicks, 500 Hz toneburst, 3000 Hz toneburst) at two electrode scalp positions (Fz and Cz). For the first AMLR acquired (chronic), participants abstained from smoking for two hours prior. The second AMLR (acute), was acquired immediately after the participant smoked a cigarette. Only the first acute AMLR waveform was analyzed to optimize any immediate smoking effects given nicotine’s half-life of 2 minutes. Data management included waveform analysis (amplitudes, latencies, morphology) using SmartEP IHS software and data transfer to a spreadsheet. Group data of latencies and relative amplitudes will be examined to explore the research questions. Statistical analysis is underway in SPSS using mixed model ANOVA.

In this presentation, results are reported for a portion of the AMLR data acquired at the Fz electrode site. The AMLR was consistently and reliably recorded in all 22 participants. Preliminary findings from waveform analyses revealed a distinct morphological difference between click and toneburst stimuli. Further analysis for acute smoking effects in younger versus older adults as well as stimulus considerations is pending completion of statistical analysis. Findings may supplement clinical AMLR utilizations by providing additional knowledge concerning anticipated waveform characteristics when testing adult populations across stimuli conditions. This study potentially has strong clinical implications regarding stimuli selected for AMLR protocols, case history, and test scheduling (i.e, time of day, abstinence period for smoking clients, etc.).