APOE gene-dependent BOLD responses to a breath-hold across the adult lifespan.

Age and apolipoprotein E (APOE) e4 genotype are two of the strongest known risk factors for sporadic Alzheimer's disease (AD). Neuroimaging has shown hemodynamic response changes with age, in asymptomatic carriers of the APOE e4 allele, and in AD. In this study, we aimed to characterize and differentiate age- and APOE gene-specific hemodynamic changes to breath-hold and visual stimulation. A further aim was to study whether these responses were modulated by 3-day intake of nitrate, a nitric oxide (NO) source. The study was designed as a randomized, double-blinded, placebo-controlled crossover study, and the study cohort comprised 41 APOE e4 carriers (e3/e4 or e4/e4 genotype) and 40 non-carriers (e3/e3 genotype) aged 30-70 years at enrollment. The participants underwent two scanning sessions, each preceded by ingestion of sodium nitrate or sodium chloride (control). During functional magnetic resonance imaging (fMRI) sessions, participants performed two concurrent tasks; a breath-hold task to probe cerebrovascular reactivity and a visual stimulation task to evoke functional hyperemia, respectively. We found that the blood oxygenation level dependent (BOLD) hemodynamic response to breath-hold was altered in APOE e4 carriers relative to non-carriers. Mid-aged (50-60 years of age) e4 carriers exhibited a significantly increased peak time relative to mid-aged e3 carriers, and peak time for younger (30-40 years of age) e4 carriers was significantly shorter than that of mid-aged e4 carriers. The response width was significantly increased for e4 carriers. The response peak magnitude significantly decreased with age. For the visual stimulation task, we found age-related changes, with reduced response magnitude with age but no significant effect of APOE allele type. We found no effect of nitrate ingestion on BOLD responses evoked by the breath-hold and visual stimulation tasks. The APOE gene-dependent response to breath-hold may reflect NO-independent differences in vascular function.

Genetic predisposition to breath-hold diving-induced hemoptysis: Preliminary study.

INTRODUCTION: Breath-hold diving-induced hemoptysis (BH-DIH) has been reported in about 25% breath-hold divers (BHD) and is characterized by dyspnea, coughing, hemoptysis and chest pain. We investigated whether eNOS G894T, eNOS T786C and ACE insertion/deletion I/D genetic variants, are possible BH-DIH risk factors. METHODS: 108 experienced healthy instructor BHDs with the same minimum requirements (102 male, six female; mean age 43.90 ± 7.49) were studied. We looked for different eNOS G894T, eNOS T786C and ACE insertion/ deletion genetic variants between BH-DIH-positive and BH-DIH-negative subjects to identify the variants most frequently associated with BH-DIH. RESULTS: At least one BH-DIH episode was reported by 22.2% of subjects, while 77.7% never reported BH-DIH. The majority of BH-DIH-positive subjects showed eNOS G894T (p = 0.001) and eNOS-T786C (p = 0.001) genotype "TT" (high-risk profile). Prevalence of BH-DIH was higher in subjects with eNOS G894T TT genotype (50%) than in subjects with GT (9.5%, p < 0.001) and GG (24%, (p = 0.0002) genotype (low-risk profile). Similar results were observed for eNOS T786C: BH-DIH prevalence was higher in the TT genotype (41.2%) group than in the CT (15.4%, p < 0.001) and CC genotype (9.1%, p < 0.001) groups. BH-DIH prevalence was significantly higher in subjects showing ACE ID genotype (34.5%) than II (0%, p < 0.001) and DD (10.5%, p = 0.0002). Of the ACE "II" genotype group, 100% never developed BH-DIH. DISCUSSION: eNOS-G894T, eNOS-T786C and ACE influence NO availability and regulation of peripheral vascular tone and blood flow. Different genetic variants of eNOS-G894T, eNOS-T786C and ACE appear significantly related to the probability to develop BH-DIH (p < 0.001).

Breath holding spells: point prevalence and associated factors among Turkish children.

BACKGROUND: Breath holding spells (BHS) are known as paroxysmal non-epileptic disorder. There are two subtypes of BHS: cyanotic and the pallid. BHS have been reported to occur in 0.1-4.6% of children in Western countries. Although it is easy to diagnose in its typical form, the data on prevalence of BHS are insufficient in developing countries. METHODS: This study was performed in Turkey's Eskisehir province. A total of 1000 randomly selected 0-6-year-old children were invited to family health centers. A specific questionnaire was given to parents. Children who had a history BHS were referred to the hospital to for investigation of medical history and neurological examinations. RESULTS: A total of 933 children participated and were included in analysis. Thirty-four children (3.6%) had had BHS. Children's birthweight, parent consanguinity and mothers' education status significantly affected the frequency of BHS. Increase in birth sequence decreases the risk of BHS 0.65-fold. Fathers' education status also affected the prevalence of BHS, with the risk of BHS being 0.39-fold less if the father had completed high school or some higher education. And, as the age of the fathers increased, the risk that their children would have BHS was 1.14-fold higher. CONCLUSIONS: Although the calculated prevalence rate was compatible with previous studies, positive family history for BHS, birth sequence, parents' education status and fathers' age were identified as risk factors associated with BHS.