(HealthDay)—Biological changes in the brain may underlie a relationship between sleep disordered breathing (SDB) and Alzheimer's disease, according to new research. A trio of studies on the matter were scheduled for presentation at the annual Alzheimer's Association International Conference, held from July 16 to 20 in London.

In one study led by Amanda Shim, from Wheaton College in Illinois, the researchers looked at β-amyloid-42 accumulation in 516 cognitively normal individuals. The researchers found that people with SDB had higher levels in cerebrospinal fluid (CSF) at baseline and more rapid accumulation over time. Moreover, Shim's team did not find a connection between obstructive sleep apnea (OSA) and the APOE e4 gene.

In a second study, Megan Hogan, also of Wheaton College, and colleagues did a similar analysis, which looked at the effects of OSA in 798 patients with mild cognitive impairment. Hogan's team found that levels of β-amyloid were higher in those with OSA than among those without the condition.

In a final report, Omonigho Michael Bubu, M.D., M.P.H., an instructor of applied health science at Wheaton College, assessed both groups in the first and second studies plus 325 patients with Alzheimer's disease. Bubu found an association between OSA and β-amyloid levels in patients with mild cognitive impairment and in those with Alzheimer's. β-amyloid also decreased in CSF and increased in the brain more quickly, and tau protein levels increased, among those with OSA whether they had normal mental function or mild cognitive impairment, Bubu added.

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