Obstructive sleep apnea (OSA) is characterized by repeated pharyngeal obstruction during sleep, causing apnea or hypopnea. Respiratory events cause arousals, fragmented sleep, and are often accompanied by oxygen desaturation for a period of more than 10 s 1. Patients with OSA have depressive symptoms, anxiety, and poor concentration 2. These psychological consequences occur in addition to medical disorders such as hypertension, diabetes, and cardiovascular diseases 3,4. The underlying mechanisms that elicit the relation between apnea and psychiatric sequalae are not clear. The mood disturbance may be psychological or biological sequences of sleep apnea, although some researchers suggest that both conditions may contribute toward the underlying common mechanism. Irrespective of how sleep apnea is linked to depression and cognitive impairment, patients with OSA have impaired quality of life 1. Following continuous positive airway pressure (CPAP) treatment, it was observed that there was improvement in depression and neurocognitive deficits 5.
To assess depression, anxiety, and executive functions in patients with OSA before and after treatment with CPAP.
Participants and methods
This was an interventional follow-up study. Twenty male and female patients with OSA (30–50 years old) were selected as a systematized random sample from the outpatient clinic of pulmonology in the International Hospital of Bahrain. Patients were diagnosed with OSA by the pulmonology consultant through an assessment of medical history, medical clinical examination, and polysomnography. Delirious patients, patients receiving psychoactive medication, and those with a history of psychiatric disorders were excluded from the study. Patients were also excluded if they had a history of heart, liver, or renal disease, diabetes, psychosis, narcolepsy, current alcohol or drug abuse, severe asthma, or cerebrovascular disease. Patients’ assessment was carried out twice: the first assessment before receiving any form of therapeutic intervention and the second 4 weeks after treatment with CPAP. The patients were receiving the CPAP daily during sleep throughout the 4 weeks before the second assessment, aiming to allow deficits in executive functions to return to their basic level. Informed written consent was obtained from all patients before enrollment in the study.
Patients’ assessment was carried out using the following tools:
- Full clinical Kasr El-Eini psychiatric sheet by a consultant psychiatrist and a psychiatric diagnosis, if any, according to the Diagnostic and Statistical Manual of Mental Disorders, 4th ed. 6.
- Polysomnography was used to diagnose, or rule out, many types of sleep disorders including sleep apnea with reporting of electroencephalogram, ECG, and electro-oculography during sleep with closed nurse observation. Sleep apnea was reported when oxygen desaturation occurred (reported by oxymetry) and ended with arousal 7. Sleep apnea was diagnosed when the patient had more than five attacks of apnea during sleep. Eighty-five percent of patients had a moderate (15–30 attacks) to severe form (>30 attacks) of sleep apnea during sleeping hours. Fifteen percent of patients had the mild form (5–15 attacks).
- Hamilton Rating Scale for Depression (HRSD) 8: it includes 24 items for the assessment of depressive symptoms, but not diagnostic.
- Hamilton Anxiety Scale (HAS) 9: it includes 13 items for the assessment of the severity of anxiety.
- Executive interview (EXIT) for global assessment and executive functions 10: the EXIT25 consists of 25 items or short tasks all described in the literature as reflecting frontal dysfunction. Each item was scored from 0 to 2 scores. The tasks are presented to the patient in rapid succession and with minimal instruction, which allows little time for reflection and therefore may enhance any tendency of disinhibition or inappropriate responses 11.
Analysis of data
Means with SD or percentage were used for sample comparison between groups using the unpaired t-test. The Spearman correlation coefficient was used to determine the association between numerical variables.
- The threshold of significance was fixed at 5% (P-value).
- A P-value more than 0.05 indicated a nonsignificant result.
- A P-value less than 0.05 was considered significant, and the P-value indicated the degree of significance 12.
The mean age of the patient group was 43.65±4.12 years. The mean years of education for the entire sample was 16.20±3.21 years. BMI was 37.6±3.21. Fourteen patients (70%) were men and six (30%) were women with the following characteristics.
Table 1 shows that the female sample was significantly older that the male sample and had significantly less years of education. Women were more significantly anxious and depressed than men. They had lower scores on executive functions, but not to a significant level.
Table 2 shows that 45% of patients had major depressive disorder (NOS), 35% had adjustment with depressed mood, and 20% had anxiety (NOS).
Table 3 shows a significant decrease in depression and anxiety following CPAP.
Table 4 shows a significant improvement in total executive functions, shifting, preservation, working memory, and attention following CPAP treatment.
Table 5 shows that there was a significant negative correlation between the total score of executive function and the duration of sleep apnea, with no significance in depression or anxiety scores.
The mean age of the patients was 43.65±4.12 years, and this was not in agreement with the study of Sharafkhaneh et al.13, in which the mean age of the patients was 57.4±12.47 years. This difference may be because of the nature of the study. Sharafkhaneh and colleagues’ study was a cohort study with a larger sample of patients. Patient included with 30–50 years old to have the same executive skills. In terms of sex, our study had a higher percentage of men (70%) compared with women (30%). This was in agreement with the study of Dominci and Gomes 14 and Pillar and Lavie 15, in which 74.8 and 87.05% of the patients were men and 25.2 and 12.94% were women, respectively; this agreement indicates the higher incidence of sleep apnea in men than in women.
Female patients were significantly more depressed and anxious than male patients. Also, they had greater cognitive impairment than male patients. This result was in agreement with that of Shepertycky et al.16, who found that female patients had more affective symptoms and cognitive decline than male patients. This consistency can be explained by the nature of female patients who have less expressive abilities and more emotional suffering. Also, the older age of presentation in female than male patients may be responsible for the greater cognitive decline.
This study showed comorbidities in the form of depressive disorder (not otherwise specified) (35%), adjustment disorder with depressed mood (45%), and anxiety disorder (20%). On using the psychometric tools, the mean score of patients was 29.4±8.26 on HRSD and 24.9±4.79 on HAS. This result was in agreement with that of Dominci and Gomes 14, Schröder and O’Hara 17, Leonnard 18, and Sateia 5, who found increased incidence of depressive symptoms in patients with OSA. This consistency can be attributed to sleep fragmentation and oxygen desaturation during sleep. Sleep fragmentation is a direct consequence of recurrent microarousal associated with apnea and hypopnea, wherein nocturnal hypoxemia is because of an intermittent decrease in oxygen saturation caused by respiratory events 19.
However, Wu et al.20 suggested that sleep apnea is a protective factor against depression as it could be explained by the effect of sleep restriction on improvement of depression in depressed patients. This may be attributable to the different sample sizes, sex distributions, populations in the study, and psychoactive drugs administered in Wu and colleagues study. Also, Tourian 21 reported that there is no association between OSA and depression or anxiety and he attributed the presence of depressive symptoms to obesity and other metabolic syndromes associated with sleep apnea.
Following the administration of CPAP, the mean scores of HRSD and HAS decreased significantly to 13.85±5.35 and 12.1±3.97, respectively. This result was in agreement with that of Kawahara et al.22 and Kjelsberg et al. 23, who reported a significant decrease in depression and anxiety symptoms after treatment with CPAP despite the nonexistence of a correlation between psychological symptoms and CPAP in their studies. Also, we found that there was no correlation between depression and anxiety scores in relation to the oxygen saturation and duration of sleep apnea. Although we can surmise that the improvement in depression and anxiety can be attributed to better sleep patterns and improvement in oxygen saturation following CPAP, impairment in executive functions was also noted in patients, and this could be explained by the low scores on EXIT (24.5±5.82). This impairment in executive function showed improvement following CPAP. This result was in agreement with the result of Sateia 5 and Canessa and Ferini-Strambi 24, who reported that improvement in cognitive functions correlated better with the degree of blood gas abnormalities and sleep fragmentation. However, Bedard et al. 25 found a persistence in executive impairment following CPAP and this may be because of the noncompliance of patients under treatment and the older age of the patients in this study. In terms of the subtypes of executive functions, there was a significant improvement in attention, preservation, working memory, and shifting after treatment with CPAP. The OSA patients were evaluated in a baseline condition and in follow-up treatment sessions after 4 weeks of CPAP. Ferini-Strambi et al. 26 found that patients with OSA showed a significant impairment, compared with controls, in tests for sustained attention, executive function, motor performance, and constructional abilities. All these cognitive affection were improved after a 15-day CPAP treatment.
A significant negative correlation was found between the duration of sleep apnea and the level of executive impairment; this result was in agreement with that of Beebe and Gozal 27, who described a comprehensive model explaining that prolonged duration of sleep apnea was related to greater fragmentation of sleep with intermittent hypoxia and that hypercapnia can disturb the cellular or chemical homeostasis and disturb the restorative function of sleep, which may lead to prefrontal cortical dysfunction.
Patients with OSA have psychological and cognitive deficits that affect their daily activities. Executive and psychological deficits can be reversed by compliance of patients on CPAP. CPAP is highly beneficial in the improvement of not only the medical condition but also the associated psychological status.
- Small sampling.
- Presence of associated psychological disorders that may affect the executive functions.
Conflicts of interest
There are no conflicts of interest.
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