Findings from a recent study showed that poor sleep quality in Gulf War veterans was linked to lower brain tissue volume, with lower brain volume occurring independent of some patients’ comorbid psychiatric diagnoses.
Secondary analysis of magnetic resonance images and clinical data showed that 144 Gulf War veterans who reported lower sleep quality were found to have decreased total cortical and frontal gray matter volume.
“Previous imaging studies have suggested that sleep disturbances may be associated with structural brain changes in specific regions of the frontal lobe such as the medial prefrontal and orbitofrontal cortex,” wroteLinda L. Chao, PhD, in an interview withHealio.com/psychiatry. “The surprising thing about our finding is that it suggests poor sleep quality is associated with reduced gray matter volume throughout the entire frontal lobe and also globally in the brain.”
Linda L. Chao
Chao and colleagues in the Department of Radiology and Biomedical Imaging and Psychiatry at the University of California, San Francisco, measured sleep quality using the Pittsburgh Sleep Quality Index (PSQI), which assesses sleep efficiency, perceived sleep quality and daily disturbances.
Structural MRI data were gathered using a 1.5-T scanner; the data were used to calculate total cortical, lobar gray matter and hippocampal volumes. Researchers excluded poor imaging results, which led to 144 veterans’ data being used in the study out of an original pool of 247.
The study used a Structured Clinical Interview for DSM-5 (SCID) which found concurrent Axis I diagnoses in a majority of study participants:
58 participants (40%) had lifetime major depression disorder (MDD) and 18 (13%) had current MDD.
26 participants (18%) had current PTSD and 28 (19%) were diagnosed with PTSD earlier in life, but no longer met criteria for current PTSD.
4 participants (3%) had anxiety disorders other than PTSD, and 1 participant (1%) had obsessive compulsive disorder (OCD).
72 participants (50%) had past alcohol abuse/dependence histories, and 24 participants (17%) had past substance abuse/dependence histories.
Other variable conditions that the study sought to isolate included 32 reported cases (18%) of Gulf War Illness and 18 cases (13%) of low-level sarin exposure.
Part of the research team’s analysis compensated for potential sleeping difficulty due to sleep apnea and sleep-related breathing disorders; further data included a survey on snoring, breathing difficulty and body mass index.
The researchers used multiple linear regressions to chart the relationship between brain volume and PSQI measurements; moreover, the researchers adjusted for measurements of variables including age, intracranial volume and SCID diagnoses that had a measured effect on PSQI. These included PTSD, MDD, OCD, anxiety disorders, Gulf War Illness, and adult and childhood trauma.
The study findings show that poor sleep quality in Gulf War veterans was linked with decreased frontal lobe gray matter volume. After accounting for comorbid Axis I conditions, the researchers saw a continued decrease in PSQI-rated sleep quality.
“Frontal lobe volume may be associated with poorer sleep quality or decreased capacity for sleep to be experienced as restorative,” Chao wrote in the study. “Our results suggest that poor sleep quality, which has been linked to impaired psychosocial, physical and occupational functioning, is associated with frontal lobe atrophy independent of trauma exposure, current and lifetime PTSD symptom severity, current MDD and [Gulf War Illness] status.”
Chao also commented on the potential for continued research on the relationship between frontal lobe volume and sleep quality. “Future work will be needed to examine if effective treatment of disturbed sleep leads to improved frontal lobe structural and functional integrity.”
“A lot of people try to squeeze more hours into their busy lives by sleeping as little as possible,” Chao said in the interview. “There are many things that seem more important than getting a few more hours of sleep. However, our study’s result suggest that the quality of our sleep not only affects the quality of our waking life; it also affects brain volume.”
Disclosure: This study was supported by the Department of Defense and Mental Illness Research and Education; the Clinical Center of the US Veterans Health Administration; and the Mental Illness Research, Education and Clinical Center at VA VISN 21.