Protective role of brain derived neurotrophic factor (BDNF) in obstructive sleep apnea syndrome (OSAS) patients.

Obstructive sleep apnea syndrome (OSAS) is a common disorder characterized by repeated episodes of upper airways collapse during the sleep. The following intermittent hypoxia triggers a state of chronic inflammation, which also interests the nervous system leading to neuronal damage and increased risk of cognitive impairment. Brain derived neurotrophic factor (BDNF) is a growth factor often associated with neuroplasticity and neuroprotection whose levels increase in several condition associated with neuronal damage. However, whether patients affected by OSAS have altered BDNF levels and whether such alteration may be reflective of their cognitive impairment is still controversial. Here we show that, when compared to healthy control volunteers, OSAS patients have increased serum levels of BDNF. Moreover, OSAS patients with the higher levels of BDNF also have reduced neurocognitive impairment as measured by The Montreal Cognitive Assessment (MoCA) questionnaire. Treatment with standard non-invasive mechanical ventilation (CPAP) also was able to ameliorate the level of cognitive impairment. Altogether our results indicate that BDNF levels represent a neuroprotective response to intermittent hypoxia in OSAS patients.

Effect of OSAS on cerebral vasoreactivity and cIMT before and after CPAP treatment.

INTRODUCTION: Obstructive sleep apnea syndrome (OSAS) has been shown to be an important risk factor for ischaemic cerebral disease. Specific Doppler parameters may be used to measure cerebral vascular dynamics opening the door to new markers/predictors of risk. The objective of our study was to shed light on how the treatment of OSA with continuous positive airway pressure (CPAP) may have an impact on these parameters and, consequently, lower the risk of cerebral ischemic events in these patients. METHODS: A total of 40 untreated patients diagnosed with moderate to severe obstructive sleep apnoea were submitted to a comprehensive ultrasonographic transcranial Doppler evaluation. The parameters measured were: Breath holding index (BHI), mean blood flow velocity (MBFV) and pulsatility index in middle cerebral artery. Colour Doppler ultrasound was also used to measure carotid intima-media thickness (cIMT). These parameters were compared before and after CPAP treatment. RESULTS: After CPAP treatment, MBFV and BHI were shown to be increased (without statistical significance), while cIMT and polysomnographic parameters were significantly decreased. CONCLUSION: The improvement of cerebral vasoreactivity parameters and cIMT after long-term CPAP treatment suggest that treatment of OSA may influence the cerebral vascular regulation and consequently reduce the risk of stroke.

Reversibility test in the early stages of bronchial asthma.

In the early stages of bronchial asthma, it is frequent to find subjects with a positive history and an FEV1 or FEV1/FVC > 80% of the predicted value. This study investigated if the test of reversibility showed a reversible airway obstruction (RAO) in 291 subjects with the above clinical and functional features. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and expiratory flows (PEF, MEF50, FEF(25-75)) were registered before and 20 minutes after salbutamol administration (200 mcg by MDI). Of 291 subjects, FEV1 increased in 73 (25%) after bronchodilator > or = 12% compared to baseline; the number of subjects with a > or = 35% increase in MEF50 or FEF(25-75) were similar in terms of percentage (respectively, 29.2% and 29%), whereas those with increases in FVC (> or = 12%) and in PEF (> or = 15%) were significantly lower (respectively, 2.7% and 12.3%). The percentage of subjects with RAO (FEV1 increase after bronchodilator > or = 12%) was lower (12%) in the subgroup (108 subjects), with an MEF50 > or = 70% of the value predicted at the baseline assessment, and higher (36%) in the subjects of the subgroup (183 subjects) with an MEF50 < 70%. In conclusion, it is advisable to carry out reversibility tests in all subjects with symptoms indicative of asthma even if their functional tests are "normal" because in a considerable number of cases the RAO was found to confirm the suspected diagnosis and provided a more reliable classification of the disease.