SLEEP - Cortical GABA Levels in Primary Insomnia

VOLUME 35, ISSUE 06

CORTICAL GABA LEVELS IN PRIMARY INSOMNIA
Cortical GABA Levels in Primary Insomnia

http://dx.doi.org/10.5665/sleep.1880

Peter T. Morgan, MD, PhD¹; Edward F. Pace-Schott, PhD²; Graeme F. Mason, PhD¹^,³; Erica Forselius, BA¹; Madonna Fasula, APRN¹; Gerald W. Valentine, MD¹; Gerard Sanacora, MD, PhD¹

¹Department of Psychiatry, Yale University School of Medicine, New Haven, CT; ²Department of Psychology, University of Massachusetts Amherst, Amherst, MA; ³Magnetic Resonance Center, Department of Diagnostic Imaging, Yale University School of Medicine, New Haven, CT

Table of Contents

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Study Objectives:

GABA is increasingly recognized as an important neurotransmitter for the initiation and maintenance of sleep. We sought to measure cortical GABA content through proton magnetic resonance spectroscopy (MRS) in persons with and without primary insomnia, and relate brain GABA levels to polysomnographic sleep measures.

Design:

Two-group comparison study.

Setting:

Outpatient study at a university research clinic.

Participants:

Non-medicated persons with primary insomnia (N = 16) and no sleep complaints (N = 17).

Interventions:

Participants kept sleep diaries and a regular time-in-bed schedule for 9 days, culminating in 2 consecutive nights of ambulatory polysomnography and a single proton MRS session. The main outcome measure was occipital GABA/creatine ratios; secondary measures included sleep measurements and relationship between polysomnographically measured time awake after sleep onset and occipital GABA content.

Measurements and Results:

The primary insomnia group was distinguished from persons with no sleep complaints on self-reported and polysomnographically measured sleep. The two groups did not differ in age, sex, body mass index, habitual bed- and wake-times, napping, use of caffeine, or use of cigarettes. Mean occipital GABA level was 12% higher in persons with insomnia than in persons without sleep complaints (P < 0.05). In both groups, GABA levels correlated negatively with polysomnographically measured time awake after sleep onset (P < 0.05).

Conclusions:

Increased GABA levels in persons with insomnia may reflect an allostatic response to chronic hyperarousal. The preserved, negative relationship between GABA and time awake after sleep onset supports this notion, indicating that the possible allostatic response is adaptive.

Citation:

Morgan PT; Pace-Schott EF; Mason GF; Forselius E; Fasula M; Valentine GW; Sanacora G. Cortical GABA levels in primary insomnia. SLEEP 2012;35(6):807-814.