Copyright ©ERS Journals Ltd 2001 Acute psychosis after CPAP treatment in a schizophrenic patient with sleep apnoeahypopnoea syndromePneumology Section, Hospital Universitari Sant Joan d'Alacant, Alicante, Spain CORRESPONDENCE: E. Chiner Vives, Sección de Neumología, Hospital Universitari Sant Joan d'Alacant, Carretera AlicanteValencia s/n, 03550, San Juan de Alicante, Spain. Fax: 965658750 Keywords: adverse effects, CPAP, psychosis, schizophrenia, sleep apnoeahypopnoea syndrome
Received: June 15, 1999 Abstract
A 52-yr-old man with a residual phase of schizophrenia developed sleep apnoeahypopnoea syndrome (SAHS). After five days of continuous positive airway pressure (CPAP) treatment, the patient developed an aggressive mood with incoherence, prominent hallucinations and agitation, and attempted to hit his relatives. He was finally admitted to the hospital with an acute psychotic episode. Withdrawal of CPAP, and neuroleptic treatment controlled the episode, and clinical symptoms of SAHS reappeared 10 days later.
Schizophrenia associated to sleep apnoeahypopnoea syndrome has rarely been reported, but, to the authors' knowledge, the induction of a psychotic episode by continuous positive airway pressure treatment in a patient with sleep apnoeahypopnoea syndrome and coexisting schizophrenia has never been previously reported.
Case report
A 52-yearold man was submitted to outpatient Sleep Unit because of SAHS suspicion. Ten years ago he suffered psychotic symptoms: incoherence, hallucinations, delusions, progressive deterioration in social relations and a blunted affect, with three active moderate phases during the first five years. A diagnosis of episodic schizophrenia with interepisodic residual symptoms, undifferentiated type (F20.3x(295.92), DSM-IV) was established (criteria A characteristic symptoms, B social dysfunction, C duration Polysomnographic findings were: time in bed 356 min; sleep latency 1 min; total sleep time (TST) 286 min; sleep efficiency 79%; latency to stage 1, 1 min; to stage 2, 22 min; to stage 3, 110 min; to rapid eye movement (REM) stage 50 min. Percentages of sleep referred to TST were: REM stage 3%; stage 1, 46%; stage 2, 48%; stage 3, 3%; stage 4, 0%; apnoeahypopnoea index (AHI) 52; arousal index 36; baseline arterial oxygen saturation Sa,O2 95%; minimal Sa,O2 81%.
CPAP titration was carried out on a second night, normalizing the AHI at a pressure of 8 cmH2O. Polysomnographic data under CPAP (second part of the night) were: sleep efficiency 97%; latency to stage 1, 1 min; to stage 2, 5 min; to stage 3, 100 min; to stage 4, 104 min; to REM stage, 67 min. Percentages of sleep stages referred to TST were: REM stage 13.5%; stage 1, 42%; stage 2, 35%; stage 3, 4.6%; stage 4, 5%; AHI 1; arousal index 6; mean Sa,O2 92%; minimal Sa,O2 90 %. The graphic display of hypnogram and Sa,O2 before and during CPAP is depicted in figure 1
CPAP treatment was prescribed at home. Good adaptation and compliance were reported by his wife, with progressive disappearance of daytime sleepiness. However, after five days of treatment, the patient went into an aggressive mood with incoherence, prominent hallucinations and agitation, and attempted to hit his relatives. He was finally taken to hospital by the police and admitted with an acute psychotic episode. Withdrawal of CPAP, and neuroleptic treatment controlled the episode, and clinical symptoms of SAHS reappeared ten days later. His wife refused a new CPAP treatment trial. Discussion Prevalence of sleeprelated respiratory disorders in schizophrenic patients has scarcely been studied. ZARCONE and BENSON 7 reported that 14.5% of male patients with schizophrenia had comorbid SAHS. In schizophrenic patients, TAKAHASHI et al. 8 in a study based only on oximetric data, reported a sleeprelated respiratory disorder prevalence of 21.9% for males and 13.5% for females, not higher than that in a control group.
Schizophrenia and SAHS share several sleep disturbances such as the slow wave sleep deficit and shorter REM periods frequently interrupted by waking 7, but differ in other findings such as the marked increase in sleep onset latency reported in schizophrenia. Moreover, an abnormal REM rebound following REM sleep deprivation has been described in schizophrenia, although the mechanisms for this abnormality and its relation to symptoms remain unknown 10. However, the slow wave sleep deficit and shortened REM sleep latency reported in schizophrenic patients have been criticised because most of these patients had been off neuroleptic medication for only a short period of time 11. On the other hand, technical difficulties resulting from the lack of cooperation of schizophrenic patients in an acute phase may be an added problem. A decrease in levels of serotonin and its metabolites has been associated with a deficit in stage 4 sleep, suggesting that serotonin may modulate the amount of slow wave sleep in schizophrenia 12. In this disease, cholinergic hyperactivity is related to negative symptoms, as a protective mechanism for the elevated dopaminergic activity and psychotic exacerbations 13. Changes in dopaminergic transmission have been associated with REM sleep deprivation and the subsequent rebound of this stage 14. A subpopulation of pedunculopontine neurons of the upper brainstem releasing acetylcholine, has been recognized as a critical modulator of REM sleep. Serotonin-mediated hyperpolarization of the cholinergic pedunculopontine neurons and afferent In severe SAHS there is a marked disruption of the underlying neurophysiological mechanisms of sleep, which ceases with the REM rebound occurring in the first few days of CPAP treatment 17. The present authors hypothesize that the patient had chronic sleep deprivation induced by SAHS, coexisting with the sleep disturbances of schizophrenia. The relative REM rebound and enhanced slow wave sleep, occurring after CPAP treatment for SAHS, may have increased dopaminergic activity or stimulated GABAergic pathways that modulate atonia versus cortical activation, favouring the psychotic attack. Withdrawal of CPAP may have "normalized" the equilibrium between the patient's cholinergic and dopaminergic systems, and, finally, the sleepiness of SAHS may have had a sedative effect. In conclusion, psychiatric patients must be carefully followed during the first days of continuous positive airway pressure treatment, because the psychiatric disease may be masked by the severity of sleep apnoeahypopnoea syndrome. Appropriate neuroleptic treatment should be administered in these patients before continuous positive airway pressure, in order to prevent the possible relapse of psychotic symptoms.
References
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