CPAP Withdrawal Alters Brain Function in Apnea Patients

MONTREAL – Sleep apnea patients receiving continuous positive airway pressure therapy have changes in brain function that can be seen with functional magnetic resonance imaging when the therapy is withdrawn for just 2 consecutive nights.

“The brains of these patients must work harder, and possibly in less efficient ways, to perform at the same level [as when they are on the therapy],” said Mark S. Aloia, Ph.D., who reported the findings at the 8th World Congress on Sleep Apnea.

His study included eight subjects with moderate to severe sleep apnea who were compliant with continuous positive airway pressure (CPAP) therapy. The subjects were asked to complete a cognitive function test called the N-back test while undergoing functional magnetic resonance imaging (fMRI) of their brains. The testing was performed both when patients were compliant with CPAP (at least 2 consecutive nights) and when the therapy had been withdrawn for 2 consecutive nights.

While subjects performed similarly both on and off CPAP therapy (because of extensive task training), the fMRI showed significant differences in which regions of their brains were activated in the presence or absence of CPAP, said Dr. Aloia, who serves as director of sleep research at National Jewish Medical and Research Center in Denver.

Specifically, there was significantly greater activation of the left middle frontal gyrus and a trend toward greater activation of the right inferior parietal regions when CPAP was withdrawn. In contrast, when patients had been treated with CPAP, there was significantly more activation of the right middle frontal gyrus.

The findings lend support to the hypothesis that untreated sleep apnea creates an inefficiency in brain function, Dr. Aloia said. “There seems to be a compensatory response of the brain off CPAP such that subjects are using more brain resources to perform at the same level,” he said in an interview.

In addition to altering brain function, there is also evidence that sleep apnea impairs certain cognitive functions–and CPAP can reverse some of this impairment, Dr. Aloia added. In another study currently in press, he found that sleep apnea patients with impaired memory were eight times more likely to normalize their memory if they received adequate CPAP therapy–defined as 3 months of 6 or more hours per night–compared with patients who were less compliant with CPAP, averaging 1 hour or less a night.

Dr. Aloia and his colleagues also have done imaging studies that show differences in white matter in the brains of patients with severe sleep apnea, compared with those with mild disease–suggesting that some of the changes in brain functioning among sleep apnea patients could be caused by microvascular damage.

“From a neuropsychological perspective, we see fine motor discoordination, memory, and executive problems in microvascular disease,” he said. “So, we posited the idea that the relationship we know between apnea and cardiovascular disease probably extends to vessels in the brain.”

It is possible that CPAP therapy might reverse some of this ischemia, Dr. Aloia said.

Functional magnetic resonance imaging shows that activity in the brain increases (red areas) when continuous positive airway pressure is withdrawn. Courtesy Dr. Mark S. Aloia

MONTREAL – Sleep apnea patients receiving continuous positive airway pressure therapy have changes in brain function that can be seen with functional magnetic resonance imaging when the therapy is withdrawn for just 2 consecutive nights.

“The brains of these patients must work harder, and possibly in less efficient ways, to perform at the same level [as when they are on the therapy],” said Mark S. Aloia, Ph.D., who reported the findings at the 8th World Congress on Sleep Apnea.

His study included eight subjects with moderate to severe sleep apnea who were compliant with continuous positive airway pressure (CPAP) therapy. The subjects were asked to complete a cognitive function test called the N-back test while undergoing functional magnetic resonance imaging (fMRI) of their brains. The testing was performed both when patients were compliant with CPAP (at least 2 consecutive nights) and when the therapy had been withdrawn for 2 consecutive nights.

While subjects performed similarly both on and off CPAP therapy (because of extensive task training), the fMRI showed significant differences in which regions of their brains were activated in the presence or absence of CPAP, said Dr. Aloia, who serves as director of sleep research at National Jewish Medical and Research Center in Denver.

Specifically, there was significantly greater activation of the left middle frontal gyrus and a trend toward greater activation of the right inferior parietal regions when CPAP was withdrawn. In contrast, when patients had been treated with CPAP, there was significantly more activation of the right middle frontal gyrus.

The findings lend support to the hypothesis that untreated sleep apnea creates an inefficiency in brain function, Dr. Aloia said. “There seems to be a compensatory response of the brain off CPAP such that subjects are using more brain resources to perform at the same level,” he said in an interview.

In addition to altering brain function, there is also evidence that sleep apnea impairs certain cognitive functions–and CPAP can reverse some of this impairment, Dr. Aloia added. In another study currently in press, he found that sleep apnea patients with impaired memory were eight times more likely to normalize their memory if they received adequate CPAP therapy–defined as 3 months of 6 or more hours per night–compared with patients who were less compliant with CPAP, averaging 1 hour or less a night.

Dr. Aloia and his colleagues also have done imaging studies that show differences in white matter in the brains of patients with severe sleep apnea, compared with those with mild disease–suggesting that some of the changes in brain functioning among sleep apnea patients could be caused by microvascular damage.

“From a neuropsychological perspective, we see fine motor discoordination, memory, and executive problems in microvascular disease,” he said. “So, we posited the idea that the relationship we know between apnea and cardiovascular disease probably extends to vessels in the brain.”

It is possible that CPAP therapy might reverse some of this ischemia, Dr. Aloia said.

Functional magnetic resonance imaging shows that activity in the brain increases (red areas) when continuous positive airway pressure is withdrawn. Courtesy Dr. Mark S. Aloia

MONTREAL – Sleep apnea patients receiving continuous positive airway pressure therapy have changes in brain function that can be seen with functional magnetic resonance imaging when the therapy is withdrawn for just 2 consecutive nights.

“The brains of these patients must work harder, and possibly in less efficient ways, to perform at the same level [as when they are on the therapy],” said Mark S. Aloia, Ph.D., who reported the findings at the 8th World Congress on Sleep Apnea.

His study included eight subjects with moderate to severe sleep apnea who were compliant with continuous positive airway pressure (CPAP) therapy. The subjects were asked to complete a cognitive function test called the N-back test while undergoing functional magnetic resonance imaging (fMRI) of their brains. The testing was performed both when patients were compliant with CPAP (at least 2 consecutive nights) and when the therapy had been withdrawn for 2 consecutive nights.

While subjects performed similarly both on and off CPAP therapy (because of extensive task training), the fMRI showed significant differences in which regions of their brains were activated in the presence or absence of CPAP, said Dr. Aloia, who serves as director of sleep research at National Jewish Medical and Research Center in Denver.

Specifically, there was significantly greater activation of the left middle frontal gyrus and a trend toward greater activation of the right inferior parietal regions when CPAP was withdrawn. In contrast, when patients had been treated with CPAP, there was significantly more activation of the right middle frontal gyrus.

The findings lend support to the hypothesis that untreated sleep apnea creates an inefficiency in brain function, Dr. Aloia said. “There seems to be a compensatory response of the brain off CPAP such that subjects are using more brain resources to perform at the same level,” he said in an interview.

In addition to altering brain function, there is also evidence that sleep apnea impairs certain cognitive functions–and CPAP can reverse some of this impairment, Dr. Aloia added. In another study currently in press, he found that sleep apnea patients with impaired memory were eight times more likely to normalize their memory if they received adequate CPAP therapy–defined as 3 months of 6 or more hours per night–compared with patients who were less compliant with CPAP, averaging 1 hour or less a night.

Dr. Aloia and his colleagues also have done imaging studies that show differences in white matter in the brains of patients with severe sleep apnea, compared with those with mild disease–suggesting that some of the changes in brain functioning among sleep apnea patients could be caused by microvascular damage.

“From a neuropsychological perspective, we see fine motor discoordination, memory, and executive problems in microvascular disease,” he said. “So, we posited the idea that the relationship we know between apnea and cardiovascular disease probably extends to vessels in the brain.”

It is possible that CPAP therapy might reverse some of this ischemia, Dr. Aloia said.

Functional magnetic resonance imaging shows that activity in the brain increases (red areas) when continuous positive airway pressure is withdrawn. Courtesy Dr. Mark S. Aloia