Brain Gray Matter Deficits in Patients with Chronic Primary Insomnia

Abstract

STUDY OBJECTIVE: To investigate the structural changes in patients with chronic primary insomnia and the relationships with clinical features of insomnia. DESIGN: Statistical parametric mapping 8-based voxel-based morphometry was used to identify differences in regional gray and white matter between patients with chronic primary insomnia and normal controls. SETTING: University hospital. PATIENTS AND PARTICIPANTS: Twenty-seven patients and 27 age/sex-matched controls. INTERVENTIONS: -tests with age, sex, and intracranial volume as covariates. MEASUREMENTS AND RESULTS: The patients were a mean age of 52.3 y and had a mean history of insomnia of 7.6 y. Patients displayed cognitive deficits in attention, frontal/executive function, and nonverbal memory. Patients also displayed significantly reduced gray matter concentrations (GMCs) in dorsolateral prefrontal and pericentral cortices, superior temporal gyrus, and cerebellum and decreased gray matter volumes in medial frontal and middle temporal gyri compared with control patients with the cluster threshold ≥ 50 voxels at the level of uncorrected P < 0.001. Negative correlations were found between GMC of the prefrontal cortex and insomnia severity and the wakefulness after sleep onset, and between GMC of pericentral cortex and sleep latencies. None of the findings continued to be significant after correction for multiple comparisons. CONCLUSIONS: We found gray matter deficits in multiple brain regions including bilateral frontal lobes in patients with psychophysiologic insomnia. Gray matter deficit of the pericentral and lateral temporal areas may be associated with the difficulties in sleep initiation and maintenance. It is still unclear whether gray matter reductions are a preexisting abnormality or a consequence of insomnia. CITATION: 2013;36(7):999-1007.