Sleep architecture, cocaine and visual learning

Objective sleep outcomes in randomized-controlled trials in persons with substance use disorders: A systematic review

BACKGROUND

Improving sleep health is an important target for substance use disorder (SUD) research. However, there is little guidance for SUD researchers regarding the use of technologies to objectively assess sleep outcomes in randomized-controlled trials (RCTs). This systematic review aimed to describe the use of technologies to objectively measure sleep outcomes in RCTs conducted in persons with SUDs, in order to inform future sleep intervention studies in SUD populations.

METHODS

This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) on May 7th, 2020 (CRD42020182004). RCTs were reviewed here if they were peer-reviewed manuscripts that included objective measures of sleep in RCTs that sought to improve sleep in persons with SUDs.

RESULTS

The initial search yielded 13,403 potential articles, with 27 meeting a priori criteria to be included in this review. The most common SUD was alcohol use disorder (59%). The most common technology used to assess sleep was polysomnography (41%), followed by actigraphy (37%), ambulatory polysomnography or components of polysomnography (e.g., electroencephalography; 19%), and at-home sleep apnea testing (7%). The most common sleep outcome reported was total sleep time (96%).

CONCLUSIONS

There are a range of options to assess objective sleep outcomes. Polysomnography or ambulatory devices that directly measure brain activity are critical to advance medications through the regulatory process for the indication of improving sleep duration, continuity, and/or sleep onset latency outcomes. Actigraphy is also useful in preliminary investigations and in detecting the relationship between diurnal and SUD-related behaviors.

Interaction between cocaine use and sleep behavior: A comprehensive review of cocaine's disrupting influence on sleep behavior and sleep disruptions influence on reward seeking

Dopamine, orexin (hypocretin), and adenosine systems have dual roles in reward and sleep/arousal suggesting possible mechanisms whereby drugs of abuse may influence both reward and sleep/arousal. While considerable variability exists across studies, drugs of abuse such as cocaine induce an acute sleep loss followed by an immediate recovery pattern that is consistent with a normal response to loss of sleep. Under more chronic cocaine exposure conditions, an abnormal recovery pattern is expressed that includes a retention of sleep disturbance under withdrawal and into abstinence conditions. Conversely, experimentally induced sleep disturbance can increase cocaine seeking. Thus, complementary, sleep-related therapeutic approaches may deserve further consideration along with development of non-human models to better characterize sleep disturbance-reward seeking interactions across drug experience.

Sleep time differs among people who co-use cocaine and cannabis compared to people who only use cocaine

OBJECTIVE

People who use cocaine experience numerous sleep problems and often use cannabis to mitigate these problems. However, co-using cocaine and cannabis may result in worse sleep outcomes when compared to using cocaine only. The current study examined group differences in subjective sleep outcomes among people who use cocaine and people who co-use cocaine and cannabis.

METHODS

Participants were 82 individuals with cocaine use disorder who were enrolled in a randomized clinical trial for cocaine treatment. Sleep outcomes, assessed at baseline prior to treatment, were measured with the Saint Mary's Hospital Sleep Questionnaire and included total sleep time, perceived sleep quality, difficulty falling asleep, and daytime alertness. Analysis of covariance and Kruskal-Wallis tests were used to compare sleep outcomes between participants with urine samples that tested positive for both cocaine and cannabis at baseline, those who tested positive for cocaine only, and those who tested negative for all drugs.

RESULTS

Total reported sleep time was highest among those with a drug negative urine, followed by those with a cocaine positive urine and those who tested positive for cocaine and cannabis. There were no differences in perceived sleep quality, difficulty falling asleep, or daytime alertness between groups.

CONCLUSIONS

People who co-use cocaine and cannabis may report reduced sleep time relative to those who only use cocaine. Co-use of cannabis may exacerbate sleep difficulties in people who use cocaine by decreasing total sleep time, although it is important to note that the groups each reported similar sleep quality. Implications for treatment and directions for future research are discussed.

Simultaneous administration of cocaine and caffeine dysregulates HCN and T-type channels

RATIONALE

The abuse of psychostimulants has adverse consequences on the physiology of the central nervous system. In Argentina, and other South American countries, coca paste or "PACO" (cocaine and caffeine are its major components) is massively consumed with deleterious clinical consequences for the health and well-being of the general population. A scant number of studies have addressed the consequences of stimulant combination of cocaine and caffeine on the physiology of the somatosensory thalamocortical (ThCo) system.

OBJECTIVES

Our aim was to study ion conductances that have important implications regulating sleep-wake states 24-h after an acute or chronic binge-like administration of a cocaine and caffeine mixture following previously analyzed pasta base samples ("PACO"-like binge") using mice.

METHODS

We randomly injected (i.p.) male C57BL/6JFcen mice with a binge-like psychostimulants regimen during either 1 day (acute) or 1 day on/1 day off during 13 days for a total of 7 binges (chronic). Single-cell patch-clamp recordings of VB neurons were performed in thalamocortical slices 24 h after the last psychostimulant injection. We also recorded EEG/EMG from mice 24 h after being systemically treated with chronic administration of cocaine + caffeine versus saline, vehicle.

RESULTS

Our results showed notorious changes in the intrinsic properties of the VB nucleus neurons that persist after 24-h of either acute or chronic binge administrations of combined cocaine and caffeine ("PACO"-like binge). Functional dysregulation of HCN (hyperpolarization-activated cyclic nucleotide-gated) and T-type VGC (voltage-gated calcium) channels was described 24-h after acute/chronic "PACO"-like administrations. Furthermore, intracellular basal [Ca²⁺] disturbances resulted a key factor that modulated the availability and the activation of T-type channels, altering T-type "window currents." As a result, all these changes ultimately shaped the low-threshold spikes (LTS)-associated Ca²⁺ transients, regulated the membrane excitability, and altered sleep-wake transitions.

CONCLUSION

Our results suggest that deleterious consequences of stimulants cocaine and caffeine combination on the thalamocortical physiology as a whole might be related to potential neurotoxic effects of soaring intracellular [Ca²⁺].

Sleep Perception and Misperception in Chronic Cocaine Users During Abstinence

Study Objectives

During abstinence, chronic cocaine users experience an objective worsening of sleep that is perceived as qualitatively improving. This phenomenon has been termed "occult insomnia." The objective of this study was to determine whether chronic cocaine users experience positive sleep state misperception during abstinence.

Methods

Forty-three cocaine-dependent persons were admitted to an inpatient research facility for 12 days and 11 nights to participate in a treatment study of modafinil. Polysomnographic sleep recordings were performed on study nights 3, 4, 10, and 11, when participants were on average 1 and 2 weeks abstinent from cocaine. Participants also completed sleep diary questionnaires every evening before bed and every morning upon awakening. Polysomnographic and sleep diary measurements of total sleep time, sleep latency, time awake after sleep onset, and time in bed after final awakening were compared.

Results

Chronic cocaine users accurately reported total sleep time after 1 week of abstinence but overreported total sleep time by an average of 40 min after 2 weeks of abstinence. Underestimating sleep latency and time spent awake after sleep onset were responsible for this difference.

Conclusions

Positive sleep state misperception is revealed in chronic cocaine users after 2 weeks of abstinence and is consistent with the previously identified "occult insomnia" in this population.

Altered activity-based sleep measures in rhesus monkeys following cocaine self-administration and abstinence

BACKGROUND

Impairments in sleep and cognitive function have been observed in patients with substance abuse disorders and may be potential factors contributing to drug relapse. In addition, sleep disruption may itself contribute to cognitive deficits. In the present study we examined the impact of prolonged cocaine self-administration and abstinence on actigraphy-based measures of night-time activity in rhesus macaques as an inferential measure of sleep, and determined whether sleep-efficiency correlated with cognitive impairments in the same subjects on drug free days.

METHODS

Actigraphy data was obtained from a group of rhesus macaques intravenously self-administering cocaine (n=6) and a control group (n=5). Periods were evaluated during which the mean cumulative doses of cocaine were 3.0+0.0 and 4.5+0.2mg/kg/day for 4days (Tuesday-Thursday) each week.

RESULTS

Actigraphy-based sleep efficiency decreased during days of cocaine self-administration in a dose-dependent manner. Consistent with this observation, sleep became more fragmented. Activity-based sleep efficiency normalized during the weekend without cocaine prior to cognitive assessment on Monday. The magnitude of activity-based sleep disruption during self-administration did not correlate with the level of cognitive impairment on drug free days. With continued self-administration, the impact of cocaine on activity-based sleep efficiency declined indicating the development of tolerance.

CONCLUSIONS

Cocaine self-administration disrupted sleep efficiency in rhesus macaques as measured by actigraphy, but normalized quickly in the absence of cocaine. The cognitive impairment observed on drug free days was unlikely to be related to disruption of the nightly activity patterns on days of cocaine self-administration.

Polysomnographic measures of sleep in cocaine dependence and alcohol dependence: Implications for age-related loss of slow wave, stage 3 sleep

BACKGROUND AND AIMS

Sleep disturbance is a prominent complaint in cocaine and alcohol dependence. This controlled study evaluated differences of polysomnographic (PSG) sleep in cocaine- and alcohol-dependent subjects, and examined whether substance dependence interacts with age to alter slow wave sleep and rapid eye movement (REM) sleep.

DESIGN

Cross-sectional comparison.

SETTING

Los Angeles and San Diego, CA, USA.

PARTICIPANTS

Abstinent cocaine-dependent subjects (n = 32), abstinent alcohol-dependent subjects (n = 73) and controls (n = 108); mean age 40.3 years recruited 2005-12.

MEASUREMENTS

PSG measures of sleep continuity and sleep architecture primary outcomes of Stage 3 sleep and REM sleep. Covariates included age, ethnicity, education, smoking, body mass index and depressive symptoms.

FINDINGS

Compared with controls, both groups of substance dependent subjects showed loss of Stage 3 sleep (P < 0.001). A substance dependence × age interaction was found in which both cocaine- and alcohol-dependent groups showed loss of Stage 3 sleep at an earlier age than controls (P < 0.05 for all), and cocaine-dependent subjects showed loss of Stage 3 sleep at an earlier age than alcoholics (P < 0.05). Compared with controls, REM sleep was increased in both substance-dependent groups (P < 0.001), and cocaine and alcohol dependence were associated with earlier age-related increase in REM sleep (P < 0.05 for all).

CONCLUSIONS

Cocaine and alcohol dependence appear to be associated with marked disturbances of sleep architecture, including increased rapid eye movement sleep and accelerated age-related loss of slow wave, Stage 3 sleep.

Sleep abnormalities associated with alcohol, cannabis, cocaine, and opiate use: a comprehensive review

Sleep abnormalities are associated with acute and chronic use of addictive substances. Although sleep complaints associated with use and abstinence from addictive substances are widely recognized, familiarity with the underlying sleep abnormalities is often lacking, despite evidence that these sleep abnormalities may be recalcitrant and impede good outcomes. Substantial research has now characterized the abnormalities associated with acute and chronic use of alcohol, cannabis, cocaine, and opiates. This review summarizes this research and discusses the clinical implications of sleep abnormalities in the treatment of substance use disorders.

Modafinil and sleep architecture in an inpatient-outpatient treatment study of cocaine dependence

OBJECTIVE

To determine whether the increase in slow-wave sleep associated with modafinil treatment in chronic cocaine users mediates improved clinical outcomes.

METHOD

57 cocaine dependent participants were randomized to receive modafinil 400mg or placebo daily during a period of inpatient treatment followed by six weeks of outpatient treatment. Participants underwent polysomnographic sleep recording during inpatient treatment prior to and after starting modafinil. Outpatient treatment consisted of weekly cognitive behavioral therapy. Contingency management was used to promote participation in treatment and research demands, including thrice weekly visits during the outpatient phase for urine toxicology screens and other assessments. The primary clinical outcome was the percent of urine toxicology screens that were negative for cocaine.

RESULTS

Modafinil treatment was associated with a higher mean percentage (52% vs. 26%) of cocaine-free urine screens (p=0.02) and an increase in N3 sleep time (p=0.002). The change in N3 sleep time mediated the higher rate of cocaine-free urine screens. Modafinil treatment was also associated with more consecutive days abstinent during outpatient treatment, greater survival of abstinence, higher daily rates of abstinence, and less sleep degradation typically associated with abstinence from chronic cocaine use.

CONCLUSIONS

Morning-dosed modafinil improves slow-wave sleep in abstinent cocaine users in the inpatient setting, and this effect is a statistical mediator of improved clinical outcomes associated with continued modafinil treatment. The high rates of abstinence achieved in this trial suggest that promoting healthy sleep physiology in an inpatient setting may be important in the effective treatment of cocaine dependence.

Effects of quetiapine treatment on cocaine self-administration and behavioral indices of sleep in adult rhesus monkeys

RATIONALE

Clinical literature suggests a link between substance abuse and sleep disturbances. Quetiapine, an atypical antipsychotic, has shown efficacy in treating sleep disturbances, with clinical studies showing promise for quetiapine as a treatment for cocaine abuse.

OBJECTIVE

The goal of this study was to examine the effects of quetiapine on cocaine self-administration and behavioral indices of sleep in monkeys.

METHODS

Seven adult male rhesus monkeys, fitted with Actical® activity monitors, were trained to respond under a choice paradigm of food (1.0-g pellets) and cocaine (0.003-0.3 mg/kg per injection) presentation. First, monkeys received acute pretreatment (45 min) with quetiapine (25-75 mg, p.o.) prior to choice sessions; three cocaine doses were studied in combination with quetiapine. Next, the effect of chronic (14-16 days) quetiapine treatment (25-250 mg, p.o., BID) was examined in combination with the lowest preferred cocaine dose (≥80 % cocaine choice). Behavioral indices of sleep, based on activity measures obtained during lights-out, were recorded throughout the study.

RESULTS

Acute quetiapine decreased cocaine choice in four of the seven monkeys. Chronic quetiapine treatment resulted in initial decreases in cocaine choice, but tolerance developed to these effects. Acute doses of quetiapine did not improve sleep efficiency the following night nor did chronic quetiapine. The first night after discontinuing quetiapine treatment resulted in significant decreases in sleep efficiency and increases in nighttime activity.

CONCLUSIONS

These findings do not offer support for the use of quetiapine as a monotherapy for treatment of cocaine abuse nor as an adjunct therapy to treat sleep disturbances associated with stimulant abuse.

Correlates of polysomnographic sleep changes in cocaine dependence: self-administration and clinical outcomes

BACKGROUND

Abstinence from chronic cocaine use is associated with abnormal sleep architecture. As sleep abnormalities are associated with clinical outcome in alcohol dependence, we hypothesized a similar relationship in cocaine dependence.

METHODS

We report data from a cocaine self-administration study (N=12) and the placebo arm of a randomized clinical trial (N=20). Self-administration participants underwent three cocaine self-administration sessions during a three-week inpatient stay. Treatment participants underwent two weeks of inpatient followed by six weeks of outpatient treatment including once-weekly cognitive behavioral therapy. Measurements included polysomnography from early and late in abstinence during the inpatient stays. Clinical outcomes included amount of cocaine self-administered, urine tests, and self-reported use and withdrawal symptoms.

RESULTS

Change in slow-wave sleep from early to late abstinence (ΔSWS; p=0.05), late abstinence rapid eye movement sleep (REM; p=0.002), and late abstinence total sleep time (p=0.02) were negatively correlated with the amount of cocaine self-administered. Early abstinence REM was positively correlated with withdrawal symptoms (p=0.02). Late abstinence REM was positively correlated with percent negative urines and maximum consecutive number of days abstinent (both p<0.001). ΔSWS was positively correlated with percent negative urines (p=0.03) and participants with increased SWS had greater percent negative urines (p=0.008) and maximum consecutive number of days abstinent (p=0.009).

CONCLUSIONS

Correlations between sleep deficits and amount of cocaine self-administered, clinical outcomes, and severity of withdrawal symptoms underscore the relevance of sleep in clinical outcomes in the treatment of cocaine dependence.

Psychometric properties of the Spanish version of the Cocaine Selective Severity Assessment to evaluate cocaine withdrawal in treatment-seeking individuals

Reliable and valid assessment of cocaine withdrawal is relevant for treating cocaine-dependent patients. This study examined the psychometric properties of the Spanish version of the Cocaine Selective Severity Assessment (CSSA), an instrument that measures cocaine withdrawal. Participants were 170 cocaine-dependent inpatients receiving detoxification treatment. Principal component analysis revealed a 4-factor structure for CSSA that included the following components: 'Cocaine Craving and Psychological Distress', 'Lethargy', 'Carbohydrate Craving and Irritability', and 'Somatic Depressive Symptoms'. These 4 components accounted for 56.0% of total variance. Internal reliability for these components ranged from unacceptable to good (Chronbach's alpha: 0.87, 0.65, 0.55, and 0.22, respectively). All components except Somatic Depressive Symptoms presented concurrent validity with cocaine use. In summary, while some properties of the Spanish version of the CSSA are satisfactory, such as interpretability of factor structure and test-retest reliability, other properties, such as internal reliability and concurrent validity of some factors, are inadequate.

Preliminary evidence for normalization of risk taking by modafinil in chronic cocaine users

Modafinil, a wake-promoting agent used to treat sleep disorders, is thought to enhance cognition. Although modafinil has shown promise as a pharmacotherapy for the treatment of cocaine dependence, it is unknown to what extent cognitive effects may play a role in such treatment. We examined the effect of modafinil on the Balloon Analogue Risk Task (BART), a behavioral measure in which higher scores are purported to reflect a greater propensity for risk-taking. Thirty cocaine dependent individuals, enrolled in a randomized clinical trial of modafinil 400mg (n=12) versus placebo (n=18), were administered the BART during the second week of inpatient treatment for cocaine dependence. A comparison cohort of healthy participants (n=19) performed the BART under similar conditions. Modafinil treatment was associated with significantly higher BART scores (p=0.01), which were comparable to scores in healthy persons. BART scores in placebo treated participants were much lower than previously reported in healthy participants, and lower than those observed in the comparison cohort. As propensity toward risk taking is typically associated with higher BART scores as well as increased risk for substance use, our findings may reflect a novel aspect of cognitive impairment related to chronic cocaine use. Notably, the low BART scores reflect highly suboptimal performance on the task, and the observed effect of modafinil may indicate a normalization of this impairment and have implications for treatment outcome.

Abstinence-related changes in sleep during treatment for cocaine dependence

BACKGROUND

Former sleep studies among non-treatment seeking chronic cocaine users had captured polysomnographic changes for as long as three weeks of abstinence.

METHODS

20 cocaine dependent participants, randomized to placebo in an ongoing clinical trial, received 12 days of inpatient substance abuse treatment followed by 6 weeks of outpatient cognitive behavioral therapy. Polysomnographic recording was performed on consecutive nights during the 1st and 2nd inpatient and 3rd and 6th outpatient weeks. Number of days abstinent was determined from thrice weekly urine toxicology and self-report. Polysomnographic sleep was compared between study week 1 and 2, using paired t-tests. Trajectory of total sleep time (TST) was modeled both as a linear and a quadratic function of days abstinent.

RESULTS

Despite reporting an improvement in overall sleep quality, polysomnographic sleep worsened from week 1 to 2. Among all participants, TST and stage 2 sleep time decreased, while REM sleep latency increased. Among participants who began the study with a positive urine test, there was also a decrease in REM and a trend for decreased slow wave sleep. TST compared to number of days abstinent (up to 54 days) was best fit with a quadratic model (p=0.002), suggesting the possibility of an improvement in total sleep time with extended abstinence.

CONCLUSIONS

This is the first polysomnographic characterization of sleep in a large sample of cocaine users in treatment. Present findings confirm earlier results of poor and deteriorating sleep early in abstinence, and raise the possibility of improvement after an extended abstinence.

The relationship between cocaine self-administration and actigraphy-based measures of sleep in adult rhesus monkeys

RATIONALE

Clinical trials show that chronic cocaine users suffer from sleep disturbances and preclinical research has shown that acute sleep deprivation increases the rate of cocaine self-administration in rats.

OBJECTIVE

This study examined the effect of cocaine self-administration on behavioral indices of sleep and alternatively the effect of sleep disruption on cocaine-maintained responding by rhesus monkeys.

METHODS

Seven adult rhesus monkeys, fitted with Actical® activity monitors, were trained to respond under a concurrent choice paradigm with food (three 1.0-g pellets) and cocaine (0.003-0.3 mg/kg) or saline presentation. For each monkey, the lowest preferred dose of cocaine (>80% cocaine choice) was determined. Activity data were analyzed during lights out (2000-0600) to determine sleep efficiency, sleep latency, and total activity counts. Subsequently, the monkeys' sleep was disrupted (every hour during lights-out period) the night prior to food-cocaine choice sessions.

RESULTS

Self-administration of the preferred dose of cocaine resulted in a significant decrease in sleep efficiency, with a significant increase in total lights-out activity. Sleep disruption significantly altered behavioral indices of sleep, similar to those seen following cocaine self-administration. However, sleep disruption did not affect cocaine self-administration under concurrent choice conditions.

CONCLUSIONS

Based on these findings, cocaine self-administration does appear to disrupt behavioral indices of sleep, although it remains to be determined if treatments that improve sleep measures can affect future cocaine taking.

Repeat variation in the human PER2 gene as a new genetic marker associated with cocaine addiction and brain dopamine D2 receptor availability

Low dopamine D2 receptor (D2R) levels in the striatum are consistently reported in cocaine abusers; inter-individual variations in the degree of the decrease suggest a modulating effect of genetic makeup on vulnerability to addiction. The PER2 (Period 2) gene belongs to the clock genes family of circadian regulators; circadian oscillations of PER2 expression in the striatum was modulated by dopamine through D2Rs. Aberrant periodicity of PER2 contributes to the incidence and severity of various brain disorders, including drug addiction. Here we report a newly identified variable number tandem repeat (VNTR) polymorphism in the human PER2 gene (VNTR in the third intron). We found significant differences in the VNTR alleles prevalence across ethnic groups so that the major allele (4 repeats (4R)) is over-represented in non-African population (4R homozygosity is 88%), but not in African Americans (homozygosity 51%). We also detected a biased PER2 genotype distribution among healthy controls and cocaine-addicted individuals. In African Americans, the proportion of 4R/three repeat (3R) carriers in healthy controls is much lower than that in cocaine abusers (23% vs 39%, P=0.004), whereas among non-Africans most 3R/4R heterozygotes are healthy controls (10.5% vs 2.5%, P=0.04). Analysis of striatal D2R availability measured with positron emission tomography and [(11)C]raclopride revealed higher levels of D2R in carriers of 4R/4R genotype (P<0.01). Taken together, these results provide preliminary evidence for the role of the PER2 gene in regulating striatal D2R availability in the human brain and in vulnerability for cocaine addiction.

A multistudy analysis of the effects of early cocaine abstinence on sleep

OBJECTIVE

To describe the sleep patterns of early cocaine abstinence in chronic users by polysomnographic and subjective measures.

METHODS

28 cocaine-dependent participants (ages 24-55) underwent polysomnographic sleep (PSG) recording on the 1st, 2nd and 3rd weeks of abstinence on a research dedicated inpatient facility. Objective measures of total sleep time, total REM time, slow wave sleep, sleep efficiency and a subjective measure (sleep quality) along with demographic data were collected from three different long term research studies over a five year period. Data were reanalysed to allow greater statistical power for comparisons.

RESULTS

Progressive weeks of abstinence had main effects on all assessed PSG sleep measures showing decreased total sleep time, REM sleep, stages 1 and 2 sleep, and sleep efficiency; increases in sleep onset and REM latencies and a slight increase in slow-wave sleep time were also present. Total sleep time and slow wave sleep were negatively associated with years of cocaine use. Total sleep time was positively associated with the amount of current ethanol use. Sex differences were found with females having more total REM time and an increase at a near significance level in slow wave sleep. Subjective measures were reported as improving with increasing abstinence over the same time period.

CONCLUSIONS

Chronic cocaine users show a general deterioration in objective sleep measures over a three-week period despite an increase in subjective overall sleep quality providing further evidence for "occult insomnia" during early cocaine abstinence.

Eight weeks of citicoline treatment does not perturb sleep/wake cycles in cocaine-dependent adults

BACKGROUND

Citicoline (cytidine-5'-diphosphate) is a mononucleotide composed of ribose, cytosine, pyrophosphate, and choline, and is involved in the biosynthesis of the structural phosopholipids of cell membranes. Treatment with citicoline, improves memory in patients with dementia, and reduces damage to the brain after traumatic brain injury or stroke. Recent research has been conducted to assess whether citicoline is an effective treatment for cocaine dependence. In cocaine-dependent individuals, withdrawal from cocaine is associated with disturbed sleep, which may contribute to the high rate of relapse to cocaine use. Therefore, it is important to know the impact of citicoline on the sleep/wake cycle in these individuals in order to rate its overall efficacy.

METHOD

In this double-blind, placebo-controlled trial, the effects of citicoline treatment on the sleep/wake cycles of cocaine dependent participants were assessed. The results of the current study are reported as part of a larger study, consisting of an eight-week treatment period to assess the efficacy of longer-term treatment with citicoline at decreasing cocaine consumption in cocaine-dependent polydrug using participants.

RESULTS

In this non-abstinent, cocaine-dependent population, citicoline had no effect on any of the sleep parameters measured including sleep efficiency, sleep latency, total sleep time, number of waking episodes, time awake per episode, amount of time in bed spent moving, number of sleep episodes, time asleep per episode, and amount of time in bed spent immobile.

CONCLUSIONS

These data suggest that eight weeks of citicoline administration does not disturb sleep/wake cycles of cocaine-dependent individuals.

Acute cocaine increases interleukin-1β mRNA and immunoreactive cells in the cortex and nucleus accumbens

The cytokine, interleukin-1β (IL1β) is a sleep regulatory substance whose expression is enhanced in response to neuronal stimulation. In this study, IL1β mRNA and immunoreactivity (IR) are evaluated after acute cocaine. First, IL1β mRNA levels were measured at the start or end of the light period after saline or acute exposure to a low dose of cocaine (5 mg/kg, intraperitoneal (ip)). IL1β mRNA levels after an acute exposure to cocaine (5 mg/kg, ip) at dark onset were significantly higher than those obtained from rats sacrificed after an acute exposure to saline in the piriform and somatosensory cortex, and nucleus accumbens. Acute exposure of cocaine at 5 mg/kg at dark onset also increased the number of IL1β-immunoreactive astrocytes in layer I-V of the prefrontal cortex, somatosensory cortex and nucleus accumbens. These data suggest that IL1β mRNA and protein levels in some of the dopaminergically innervated brain regions are responsive to cocaine.

Increased non-rapid eye movement sleep by cocaine withdrawal: possible involvement of A2A receptors

This study attempted to clarify whether cocaine withdrawal altered sleep architecture and the role of adenosine receptors in this process. Cocaine (20 mg/kg) was administered subcutaneously once per day for 7 days to rat implanted with sleep/wake recording electrode. Polygraphic signs of undisturbed sleep/wake activities were recorded for 24 h before cocaine administration (basal recording as control); withdrawal-day 1 (after 1 day of repeated cocaine administration), withdrawal-day 8 (after 8 days of repeated cocaine administration), and withdrawal-day 14 (after 14 days of repeated cocaine administration), respectively. On cocaine withdrawal-day 1, wakefulness was significantly increased, total sleep was decreased, non-rapid eye movement sleep was markedly reduced, and rapid eye movement sleep was enhanced. Sleep/wake cycles were also increased on cocaine withdrawal day 1. However, non-rapid eye movement sleep was increased on withdrawal-day 8 and 14, whereas rapid eye movement sleep was decreased and no significant changes were observed in the total sleep and sleep/wake cycles during these periods. Adenosine A(2A) receptors expression was increased on withdrawal-day 8 and 14, whereas A(1) receptors levels were reduced after 14 days of withdrawal and the A(2B) receptors remained unchanged. Our findings suggest that alterations of sleep and sleep architecture during cocaine subacute and subchronic withdrawals after repeated cocaine administration may be partially involved in A(2A) receptors over-expression in the rat hypothalamus.

Sleep loss and acute drug abuse can induce DNA damage in multiple organs of mice

The purpose of the present study was to characterize the genetic damage induced by paradoxical sleep deprivation (PSD) in combination with cocaine or ecstasy (3,4-methylenedioxymethamphetamine; MDMA) in multiple organs of male mice using the single cell gel (comet) assay. C57BL/6J mice were submitted to PSD by the platform technique for 72 hours, followed by drug administration and evaluation of DNA damage in peripheral blood, liver and brain tissues. Cocaine was able to induce genetic damage in the blood, brain and liver cells of sleep-deprived mice at the majority of the doses evaluated. Ecstasy also induced increased DNA migration in peripheral blood cells for all concentrations tested. Analysis of damaged cells by the tail moment data suggests that ecstasy is a genotoxic chemical at the highest concentrations tested, inducing damage in liver or brain cells after sleep deprivation in mice. Taken together, our results suggest that cocaine and ecstasy/MDMA act as potent genotoxins in multiple organs of mice when associated with sleep loss.

Normalizing effects of modafinil on sleep in chronic cocaine users

OBJECTIVE

The purpose of the present study was to determine the effect of morning-dosed modafinil on sleep and daytime sleepiness in chronic cocaine users.

METHOD

Twenty cocaine-dependent participants were randomly assigned to receive modafinil, 400 mg (N=10), or placebo (N=10) every morning at 7:30 a.m. for 16 days in an inpatient, double-blind randomized trial. Participants underwent polysomnographic sleep recordings on days 1 to 3, 7 to 9, and 14 to 16 (first, second, and third weeks of abstinence). The Multiple Sleep Latency Test was performed at 11:30 a.m., 2:00 p.m., and 4:30 p.m. on days 2, 8, and 15. For comparison of sleep architecture variables, 12 healthy comparison participants underwent a single night of experimental polysomnography that followed 1 night of accommodation polysomnography.

RESULTS

Progressive abstinence from cocaine was associated with worsening of all measured polysomnographic sleep outcomes. Compared with placebo, modafinil decreased nighttime sleep latency and increased slow-wave sleep time in cocaine-dependent participants. The effect of modafinil interacted with the abstinence week and was associated with longer total sleep time and shorter REM sleep latency in the third week of abstinence. Comparison of slow-wave sleep time, total sleep time, and sleep latency in cocaine-dependent and healthy participants revealed a normalizing effect of modafinil in cocaine-dependent participants. Modafinil was associated with increased daytime sleep latency, as measured by the Multiple Sleep Latency Test, and a nearly significant decrease in subjective daytime sleepiness.

CONCLUSIONS

Morning-dosed modafinil promotes nocturnal sleep, normalizes sleep architecture, and decreases daytime sleepiness in abstinent cocaine users. These effects may be relevant in the treatment of cocaine dependence.

Sex differences in sleep and sleep-dependent learning in abstinent cocaine users

Sleep and sleep-dependent learning are impaired in male cocaine users during abstinence, but for female users little is known. Cocaine dependent men (n=12) and women (n=14), and control participants (n=19) participated in this study of sleep and sleep-dependent learning. Cocaine users were assessed at 3, 10 and 20 days of abstinence and controls were studied over one night. Total sleep time, sleep efficiency and overnight motor learning were the main outcome measures. Cocaine dependent men compared to women exhibited deteriorations in sleep time, sleep efficiency, and overnight learning as abstinence progressed from 3 to 20 days. At abstinence day 3, cocaine dependent men and women were no different than control participants in the main outcomes. However, there were significant differences between cocaine men at abstinence day 20 and controls in sleep time and sleep-dependent learning, but no differences between controls and cocaine dependent women. There is growing evidence that sleep disturbances are associated with cocaine abuse and abstinence and have functional consequences that may be relevant to the development of effective treatments. The absence of sleep disturbances in women suggests a need to understand the mechanisms underlying these differences, as such knowledge could lead to novel therapies in cocaine dependence.