Ramesh Ghiassi

Changes in brain morphology associated with obstructive sleep apnea

OBJECTIVE Obstructive sleep apnea (OSA) causes hypoxemia and fragmented sleep, which lead to neurocognitive deficits. We hypothesised that focal loss of cortical gray matter generally within areas associated with memory processing and learning and specifically within the hippocampus would occur in OSA. METHODS Voxel-based morphometry, an automated processing technique for magnetic resonance images, was used to characterise structural changes in gray matter in seven right handed, male patients with newly diagnosed OSA and seven non-apneic, male controls matched for handedness and age. RESULTS The analysis revealed a significantly lower gray matter concentration within the left hippocampus (p=0.004) in the apneic patients. No further significant focal gray matter differences were seen in the right hippocampus and in other brain regions. There was no difference in total gray matter volume between apneics and controls. CONCLUSION This preliminary report indicates changes in brain morphology in OSA, in the hippocampus, a key area for cognitive processing.

Changes in brain morphology in patients with obstructive sleep apnoea

Background Obstructive sleep apnoea (OSA) is a common disease that leads to daytime sleepiness and cognitive impairment. Attempts to investigate changes in brain morphology that may underlie these impairments have led to conflicting conclusions. This study was undertaken to aim to resolve this confusion, and determine whether OSA is associated with changes in brain morphology in a large group of patients with OSA, using improved voxel-based morphometry analysis, an automated unbiased method of detecting local changes in brain structure. Methods 60 patients with OSA (mean apnoea hypopnoea index 55 (95% CI 48 to 62) events/h, 3 women) and 60 non-apnoeic controls (mean apnoea hypopnoea index 4 (95% CI 3 to 5) events/h, 5 women) were studied. Subjects were imaged using T1-weighted 3-D structural MRI (69 subjects at 1.5 T, 51 subjects at 3 T). Differences in grey matter were investigated in the two groups, controlling for age, sex, site and intracranial volume. Dedicated cerebellar analysis was performed on a subset of 108 scans using a spatially unbiased infratentorial template. Results Patients with OSA had a reduction in grey matter volume in the right middle temporal gyrus compared with non-apnoeic controls (p<0.05, corrected for topological false discovery rate across the entire brain). A reduction in grey matter was also seen within the cerebellum, maximal in the left lobe VIIIb close to XI, extending across the midline into the right lobe. Conclusion These data show that OSA is associated with focal loss of grey matter that could contribute to cognitive decline. Specifically, lesions in the cerebellum may result in both motor dysfunction and working memory deficits, with downstream negative consequences on tasks such as driving.

Obstructive Sleep Apnea Syndrome Is Associated with Deficits in Verbal but Not Visual Memory

RATIONALE Although cognitive deficits are well documented in patients with sleep apnea, the impact on memory remains unclear. OBJECTIVES To test the hypotheses that (1) patients with obstructive sleep apnea have memory impairment and (2) memory impairment is commensurate with disease severity. METHODS Patients with obstructive sleep apnea and healthy volunteers (apnea-hypopnea index <5 events/h) completed a test battery specially designed to differentiate between aspects of memory (semantic, episodic, and working) versus attention. Sleepiness was measured on the basis of the Epworth Sleepiness Scale and Oxford Sleep Resistance test. Memory performance in patients versus control subjects was compared (Mann-Whitney U test; P < 0.01, Bonferroni corrected for multiple comparisons) and relationships between performance and disease severity were analyzed by linear regression. MEASUREMENTS AND MAIN RESULTS Sixty patients and healthy control subjects matched for age (mean +/- SD: patients, 51 +/- 9 yr; control subjects, 50 +/- 9 yr) and education (patients, 14 +/- 3 yr; control subjects, 15 +/- 3 yr) participated. Patients demonstrated impaired Logical Memory Test results (immediate recall: patients, median [range], 36 [9-69]; control subjects, 43 [19-64], P = 0.0004; and delayed recall: patients, 22 [6-42]; control subjects, 27 [10-46]; P = 0.0001). There were minimal differences in attention, visual episodic, semantic, or working memory; patients performed better than control subjects on Spatial Span forward and backward. Regression analysis revealed that Logical Memory Test performance was not significantly related to disease severity after controlling for age, education, and sleepiness. CONCLUSIONS Obstructive sleep apnea is associated with impairment in verbal, but not visual, memory. The impairment was present across a range of disease severity and was not explained by reduced attention. Such verbal memory impairment may affect daytime functioning and performance.

Health literacy in COPD

If patients are to participate fully in their care and in the management of a long term condition such as chronic obstructive pulmonary disease, good communication is essential. However, not all patients are able to use the written word and we need to be aware of the size of this problem and its implications for the way in which we give information and conduct medical consultations. The impact of health literacy on outcomes can be considerable and improvements can be made by being aware of the problem, offering information in several different forms, and by reinforcing the spoken word with pictorial images.

The use of an online pictorial Epworth Sleepiness Scale in the assessment of age and gender specific differences in excessive daytime sleepiness

BACKGROUND Excessive daytime sleepiness (EDS) is a non-specific but highly prevalent cardinal symptom of sleep disorders. We hypothesized that with modern media and an online pictorial Epworth Sleepiness Scale (ESS) age and gender specific differences of EDS could be identified on a large scale. This could be helpful in the screening of patients with sleep disorders. PATIENTS AND METHODS In 8,098 subjects, age and gender were recorded in addition to an online pictorial ESS (range 0-24 points). The cut-off for EDS (ESS >10 points) was chosen in line with the traditional ESS. RESULTS The prevalence of EDS was slightly higher in male subjects (45% vs. 43%, P=0.033). When age was considered, female subjects tended to be sleepier in their 3(rd) and 4(th) lifetime decade (P=0.01 and P=0.003, respectively), whilst male subjects scored significantly higher in their 7(th) decade (P<0.0001); there was a trend to more daytime symptoms with higher age (P for trend <0.001). CONCLUSIONS The online pictorial ESS identifies gender differences in EDS and reveals increased levels of sleepiness associated with higher age. The use of modern media facilitates reaching out to the general population to raise awareness of conditions associated with EDS such as sleep apnoea.

Health literacy and sleep apnoea

Determining which of our patients struggle with numeracy or literacy is difficult and clinicians overestimate the levels of patient literacy.1 In a report in this journal, we demonstrate that 33% of new patients and 16% of serial users have difficulty completing the Epworth Sleepiness Scale (ESS).2 To explore reasons for this we have assessed literacy in a further group of 122 patients attending either the Sleep Centre (Sleep group) or the Lung Function Laboratory (LF group). The level of functional literacy in medicine was assessed using the Rapid Estimate of Adult Literacy in Medicine (REALM) questionnaire.3 A REALM score ≤60 suggests that the patient would struggle with patient education materials and …

A pictorial Sleepiness and Sleep Apnoea Scale to recognize individuals with high risk for obstructive sleep apnea syndrome

Purpose The aim of this study was to evaluate the validity of a new pictorial form of a screening test for obstructive sleep apnea syndrome (OSAS) – the pictorial Sleepiness and Sleep Apnoea Scale (pSSAS). Validation was performed in a sample of patients admitted to sleep clinics in the UK and Switzerland. Patients and methods All study participants were investigated with objective sleep tests such as full-night-attended polysomnography or polygraphy. The pSSAS was validated by taking into account the individual result of the sleep study, sleep-related questionnaires and objective parameters such as body mass index (BMI) or neck circumference. Different scoring schemes of the pSSAS were evaluated, and an internal validation was undertaken. Results The full data set consisted of 431 individuals (234 patients from the UK, 197 patients from Switzerland). The pSSAS showed good predictive performance for OSAS with an area under the curve between 0.77 and 0.81 depending on which scoring scheme was used. The subscores of the pSSAS had a moderate-to-strong correlation with widely used screening questionnaires for OSAS or excessive daytime sleepiness as well as with BMI and neck circumference. Conclusion The pSSAS can be used to select patients with a high probability of having OSAS. Due to its simple pictorial design with short questions, it might be suitable for screening in populations with low health literacy and in non-native English or German speakers.