By Kent Caylor, RPSGT
Researchers have discovered that obstructive sleep apnea syndrome (OSAS) increases the risk of cognitive impairment. The physiological consequences of sleep apnea can produce physical changes in the brain that have been associated with depression, anxiety, panic disorder, substance abuse, suicidal ideation, and dementia. Scientists discovered this connection through population comparison studies and further explored this with neuropsychological testing to define the level of cognitive impairment. They also performed neuroimaging to determine which regions of the brain are involved.
Investigators determined that the hippocampus and prefrontal cortex, areas of the brain closely associated with memory processes and higher-level cognitive skills, are vulnerable to sleep deprivation and hypoxemia (low oxygen levels in the blood). Cerebral autoregulation protects the brain during changes in blood pressure. However, in OSAS this mechanism is no longer able to keep up with blood pressure changes leading to hypoxemia due to low perfusion. As a result, atrophy of the hippocampus and lesions in the cerebral white matter increase with the severity of OSAS. This atrophy has been linked to cognitive dysfunction.
Both adults and children with OSAS are susceptible to cognitive decline. Several factors affect the degree of impairment: increasing age, male gender, obesity, diabetes, hypertension, and hypothyroidism. Those with comorbidities are more susceptible demonstrating that other factors play a role as well. Additionally, highly intelligent people may have a cognitive reserve that appears to be protective.
While depression is a disorder by itself, it can also be comorbid with OSAS. To complicate the problem, symptoms of depression also mimic those of OSAS. As a result, depression treatment yielding minimal results may indicate the need to reevaluate for other conditions like OSAS. Treating sleep apnea leads to improvement in shared symptoms of depression.
The AASM has estimated a staggering 8.7 million people with undiagnosed sleep apnea that have anxiety, depression or other mental health problems.
Children with OSAS display symptoms similar to Attention-Deficit/Hyperactivity Disorder (ADHD). For example, during the day, children with sleep apnea may have difficulty paying attention, perform poorly in school due to learning and behavior problems, be hyperactive, and have slower physical growth. Additionally, both attention and short-term memory can be impaired in children with sleep apnea. Many child behavioral health specialists will screen for OSA prior to rendering a diagnosis of ADHD or ADD. Studies also show that OSA is comorbid with 30% of children diagnosed with ADD or ADHD.
Sleep apnea can also cause anxiety and depression in the spouse of someone with this condition. Research has found that quality of life and depression are worse in some, but not all spouses of patients with untreated OSAS. Some studies have shown that as many as 33% of spouses suffer depression and as many as 45% from anxiety.
Kent Caylor, RPSGT is a sleep technologist at MedBridge Healthcare. This article was republished with permission. MedBridge Healthcare partners with hospitals and physician practices to offer comprehensive, fully-integrated sleep disorders services. Find out more here.