A case-matched study of neurophysiological correlates to attention/working memory in people with somatic hypervigilance

ABSTRACT

Objective: Somatic hypervigilance describes a clinical presentation in which people report more, and more intense, bodily sensations than is usual. Most explanations of somatic hypervigilance implicate altered information processing, but strong empirical data are lacking. Attention and working memory are critical for information processing, and we aimed to evaluate brain activity during attention/working memory tasks in people with and without somatic hypervigilance. Method: Data from 173 people with somatic hypervigilance and 173 controls matched for age, gender, handedness, and years of education were analyzed. Event-related potential (ERP) data, extracted from the continuous electroencephalograph recordings obtained during performance of the Auditory Oddball task, and the Two In A Row (TIAR) task, for N1, P2, N2, and P3, were used in the analysis. Between-group differences for P3 amplitude and N2 amplitude and latency were assessed with two-tailed independent t tests. Between-group differences for N1 and P2 amplitude and latency were assessed using mixed, repeated measures analyses of variance (ANOVAs) with group and Group × Site factors. Linear regression analysis investigated the relationship between anxiety and depression and any outcomes of significance. Results: People with somatic hypervigilance showed smaller P3 amplitudes—Auditory Oddball task: t(285) = 2.32, 95% confidence interval, CI [3.48, 4.47], p = .026, d = 0.27; Two-In-A-Row (TIAR) task: t(334) = 2.23, 95% CI [2.20; 3.95], p = .021, d = 0.24—than case-matched controls. N2 amplitude was also smaller in people with somatic hypervigilance—TIAR task: t(318) = 2.58, 95% CI [0.33, 2.47], p = .010, d = 0.29—than in case-matched controls. Neither depression nor anxiety was significantly associated with any outcome. Conclusion: People with somatic hypervigilance demonstrated an event-related potential response to attention/working memory tasks that is consistent with altered information processing.

KEYWORDS:

• Auditory Oddball task
• Event-related potential
• Perceptual processing
• Somatic hypervigilance
• Working memory

Acknowledgements

We acknowledge the data and support provided by BRAINnet; http://www.BRAINnet.net, under the governance of the BRAINnet Foundation. BRAINnet is the scientific network that coordinates access to the Brain Resource International Database for independent scientific purposes. We also thank the individuals who gave their time to participate in the database.

Conflicts of interest

G.L.M. has received support from Worker's Compensation boards in Australia, Europe and North America and Pfizer. He consults to Kaiser Permanente, Agile Physiotherapy and Results Physiotherapy and receives speaker's fees for lectures on pain and rehabilitation. He receives royalties for books about pain and rehabilitation. T.R.S. received financial support from Eli Lilly Ltd to cover accommodation and travel expenses during a Western Canada speaking tour. This was unrelated to the present topic.

Notes

¹ P3 = peak of activity coincident with the response to a stimulus and measured 300–600 ms after a stimulus is presented.

² Pz = Midline parietal electrode position based on the 10–20 system.

³ N2 = peak of activity coincident with the response to a stimulus and measured 180–420 ms after a stimulus is presented.

⁴ P2 = peak of activity coincident with the response to a stimulus and measured 140–270 ms after a stimulus is presented.

⁵ N1 = peak of activity coincident with the response to a stimulus and measured 80–170 ms after the stimulus is presented.

⁶ Fz = Midline frontal electrode position, based on the 10–20 system.

⁷ Cz = Midline central electrode position based on the 10–20 system.

Additional information

Funding

C.B. is supported by an Australian Postgraduate Award. G.L.M. and T.R.S. are supported by research fellowships from the National Health & Medical Research Council of Australia [ID 1061279], [ID 1054041].