Sleep apnea and the risk of dementia: A systematic review and meta-analysis.

Sleep apnea (SA) is potentially a modifiable risk factor for dementia. However, its associations to specific aetiologies of dementia remain uncertain. A systematic review and meta-analysis of cohort studies investigating the association between sleep apnea and specific aetiologies of dementia, including Alzheimer's disease (AD), Parkinson's disease (PD), Lewy body dementia (LBD), vascular dementia (VaD), and frontotemporal dementia (FTD) was performed. The use of biomarkers to support clinical diagnoses in eligible studies was collected. Eleven studies were included, comprising 1,333,424 patients. Patients with sleep apnea had an increased risk of developing any type of neurocognitive disorder (HR: 1.43 [95% CI 1.26-1.62]), Alzheimer's disease (HR: 1.28 [95% CI 1.16-1.41]), and Parkinson's disease (HR: 1.54 [95% CI 1.30-1.84]). No statistically significant association was found for vascular dementia. One study reported a two-fold increased risk for Lewy body dementia (HR: 2.06 [95% CI 1.45-2.91]). No studies investigated the risk for frontotemporal dementia and none of the studies reported results pertaining to biomarkers. Sleep apnea is associated with a significantly increased risk of dementia, particularly for Alzheimer's disease and Parkinson's disease, but not for vascular dementia. Future studies should look at the impact of sleep apnea on specific dementia biomarkers.

ACTH-dependent Cushing Syndrome with No Peripheral Response But a Marked Petrosal Sinus ACTH Response to Desmopressin.

Desmopressin is increasingly used for the diagnosis of Cushing disease (CD) since corticotropin-releasing hormone became unavailable. We report the case a 32-year-old man who presented with overt Cushing syndrome. Morning blood cortisol, ACTH, 1 mg dexamethasone suppression test, 24-hour urinary free cortisol, and bedtime salivary cortisol were highly variable, reaching markedly elevated values. Intravenous desmopressin administration produced no ACTH or cortisol increase. Pituitary magnetic resonance imaging, thoracic computed tomography, and DOTATATE positron emission tomography scan identified no lesion. Inferior petrosal sinus sampling (IPSS) with desmopressin stimulation resulted in elevated central-to-peripheral ACTH ratio and prolactin co-secretion, while peripheral ACTH remained stable. No corticotroph tumor was identified on pituitary surgery pathology. Hypercortisolism persisted postoperatively. Cabergoline was initiated, after which the patient rapidly developed transient severe adrenal insufficiency (AI). Bilateral adrenalectomy was performed in view of persistent hypercortisolism. This is an unusual case of petrosal sinus ACTH response to desmopressin without any peripheral response, suggesting a central source of ACTH. Thus, desmopressin should still be used during IPSS in patients with no peripheral response. It is unclear whether the AI episode resulted from a combination of nadir of cyclic hypercortisolism, partial apoplexy, and response to cabergoline of an occult corticotroph tumor.