REM sleep latency and neurocognitive dysfunction in schizophrenia

Abstract

Background:Cognitive deficits—the hallmark of schizophrenic deterioration—still remain elusive as far as their pathophysiology is concerned. Various neurotransmitter systems have been implicated to explain these deficits. Abnormalities in cholinergic neurotransmission in the brain are one of the postulations; acetylcholine has also been postulated to regulate rapid eye movement (REM) sleep, especially REM latency. Thus, REM latency in patients with schizophrenia might provide a non-invasive window to look into the cholinergic functions of the brain.Aim:To study REM sleep measures and neurocognitive function in schizophrenia, and the changes occurring in these parameters following pharmacological treatment.Methods:Thirty subjects (15 with schizophrenia and 15 normal non-relative controls) were evaluated in this study. Most patients with schizophrenia had prominent negative symptoms and deficits in the performance in neurocognitive tests battery. They were treated with antipsychotics for a variable period of time and post-treatment evaluation was done using the same battery of neurocognitive tests and polysomnography. Patients were either drug-naïve or kept drug-free for at least two weeks both at baseline as well as at the post-treatment stage.Results:A positive correlation between the severity of negative symptoms and neurocognitive deficits (especially on the Wisconsin Card Sorting), and a negative correlation between these two parameters and REM latency was observed.Conclusion:It can be hypothesized that the acetylcholine deficit model of dementia cannot be applied to schizophrenic dementia, rather a hypercholinergic state results. This state warrants anticholinergic medication as a treatment option for negative symptoms of schizophrenia.

Biological investigations in Indian psychiatry

“…Das et al . [ 9 ] in their study examined the correlation between REM sleep latency and neuro-cognitive functioning in 15 schizophrenia patients as measured by Wisconsin card sorting test as compared to 15 healthy controls. REM sleep latency period was determined by polysomnography, which included EEG, EOG and EMG.…”

An overview of Indian research in schizophrenia

“…On studying neurocognitive dysfunction and REM sleep latency, Das et al . [ 185 ] found a positive correlation between negative symptoms and neurocognitive deficits and a negative correlation between these parameters and REM latency. On comparing 100 patients with chronic schizophrenia with 100 matched controls on various measures of attention, executive function and memory, Srinivasan et al .…”