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Biomedical subjects

C P Pollak

Publications and source records attributed to C P Pollak.

At least 19 recordsLinked to original sources
PubMed2002

Efficacy and safety of modafinil (Provigil) for the treatment of fatigue in multiple sclerosis: a two centre phase 2 study.

OBJECTIVE: To assess the efficacy and safety of modafinil for the treatment of fatigue in multiple sclerosis (MS). METHODS: Patients aged 18-65 years with a diagnosis of MS, a stable disability level < or =6 on the Kurtzke extended disability status scale (EDSS), and a mean score >4 on the fatigue severity scale (FSS) were eligible for the 9 week, single blind, phase 2, two centre study. Exclusion criteria included a diagnosis of narcolepsy, sleep apnoea, or clinically significant major systemic disease and recent use of medications affecting fatigue. All patients, who remained blinded for the treatment regimen, received placebo during weeks 1-2, 200 mg/day modafinil during weeks 3-4, 400 mg/day modafinil during weeks 5-6, and placebo during weeks 7-9. Safety was evaluated by unblinded investigators. Efficacy was evaluated by self rating scales, using the FSS, the modified fatigue impact scale (MFIS), a visual analogue scale for fatigue (VAS-F), and the Epworth sleepiness scale (ESS). Adverse events were recorded. RESULTS: Seventy two patients (MS type: 74% relapsing-remitting; 7% primary progressive; 19% secondary progressive) received treatment. After treatment with 200 mg/day modafinil for 2 weeks, a significant improvement in fatigue versus placebo run in was demonstrated. Mean scores after treatment with 200 mg/day modafinil were: FSS, 4.7 versus 5.5 for placebo (p<0.001); MFIS, 37.7 versus 44.7 (p<0.001); and VAS-F, 5.4 versus 4.5 (p=0.003). Fatigue scores for 400 mg/day modafinil were not significantly improved versus placebo run in. Mean ESS scores were significantly improved (p<0.001) with 200 mg/day modafinil (7.2) and 400 mg/day (7.0) versus the score at baseline (9.5). Serious adverse events were not found at either dose. The most common adverse events were headache, nausea, and aesthenia. Sixty five patients (90%) completed the study. CONCLUSIONS: These data suggest that 200 mg/day modafinil significantly improves fatigue and is well tolerated in patients with MS.

Adolescent↗
PubMed2001

How accurately does wrist actigraphy identify the states of sleep and wakefulness?

STUDY OBJECTIVES: Because sleep and wakefulness differ from each other by the amount of body movement, it has been claimed that the two states can be accurately distinguished by wrist actigraphy. Our objective was to test this claim in lengthy polysomnographic (psg) and actigraphic (acf) samples that included night and day components. DESIGN: Fourteen healthy young (21-35 years) and old (70-72 years) men and women lived in a laboratory without temporal cues for 7 days. Each subject continuously wore sleep-recording electrodes as well as 2 wrist-movement recorders. Act measurements were converted to predictions of sleep and wakefulness by simple-threshold and multiple-regression methods. Psg served as the gold standard for calculation of predictive values (PV, the probability that an act prediction is correct by psg criteria). SETTING: N/A. PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The 7-day act recordings showed clear circadian cycles of high and low activity that respectively corresponded to subjective days, when subjects were wakeful, and subjective nights when they slept. Lower act levels corresponded to deeper states of psg sleep. Logistic regression on a 20-minute moving average of act gave the highest overall PV's. Nevertheless, the mean PV for sleep (PVS) was only 62.2% in complete, day + night samples. PVS was 86.6% in night samples. Act successfully predicted wakefulness during subjective nights (PVW = 89.6) and accurately measured circadian period length and the extent of sleep-wake consolidation, but it overestimated sleep rate and sleep efficiency. Act systematically decreased before sleep onset and increased before awakening, but reliable transitions among joint psg/act states (the Markov-1 property) were not demonstrated. CONCLUSIONS: Low PV's and overestimation of sleep currently disqualify actigraphy as an accurate sleep-wake indicator. Actigraphy may, however, by useful for measuring circadian period and sleep-wake consolidation and has face validity as a measure of rest/activity.

Adult↗
PubMed1998

Direct comparison of two widely used activity recorders.

Wrist actigraphy is increasingly used to track circadian rest-activity cycles and to identify states of wakefulness and sleep, yet the measurement characteristics of activity recorders have never been compared. Two widely used recorders are compared here: the MotionLogger from Ambulatory Monitoring, Inc (AM) and the Gaehwiler (G). They were worn together on the same wrist for periods averaging 41.5 hours by five members of a research team. Activity counts were stored every half-minute. Pairwise comparisons between recorders of each type showed both types to be reliable. Each also validly detected circadian rest/activity cycles. Both types suffered, however, from insensitivity. For the lower 75% of activity levels, the variance of data from the G was indeed so small as to be essentially uninformative. Since these levels include over 95% of all nocturnal data, the G must be less sensitive than the AM to small nocturnal movements, including those signifying arousal. An additional difference is that data from the AM but not the G were distributed in biphasic fashion. Biphasic activity levels are consistent with the common assumption that activity/wakefulness and rest/sleep are distinct neurobehavioral states. As the use of actigraphy increases, the important differences found here between two leading instruments point to an urgent need for standards by which activity recorders can be compared. Aspects of instrument design that could be quantitatively rated are reliability, validity, ruggedness and artifact rejection.

Circadian Rhythm↗
PubMed1998

Can panic be induced in deep sleep? Examining the necessity of cognitive processing for panic.

This study examines the relative contribution of biological and psychological processes to the induction of panic attacks by a biochemical challenge agent. Panicogenic doses of caffeine were administered to 8 panic disorder (PD) patients and 11 healthy volunteers during stage 3-4 sleep, when cognitive processing is minimal and the threshold to external stimuli is high. Panic attacks were induced directly from sleep in 3 subjects and subclinical panics in an additional 3. Subjects who experienced full panic attacks spent periods of time ranging from 4 to 52 minutes in stage 2 sleep before awakening in a panic, while those who awakened in subclinical panic awakened almost directly from stage 4 sleep. PD patients experienced significantly more panic symptoms than healthy volunteers. Although limited by a small sample size, this study suggests a combined biological-psychological model of panic induction in which panic disorder patients are more biologically predisposed than healthy controls to panic symptoms but may require cognitive processing for the elaboration of a full panic attack.

Adolescent↗
PubMed1997

How should the multiple sleep latency test be analyzed?

Results of the multiple sleep latency test (MSLT) are commonly recorded as 4-5 latencies to sleep onset, together with their mean. The suitability of these and other MSLT measures of daytime sleep tendency was examined in 111 non-narcoleptic patients of a sleep disorders center. Sleep and breathing patterns had been recorded for one night, followed by a five-nap MSLT. It was found that MSLT latencies to sleep stages 1 and 2 were distributed non-normally. There was typically an excessive frequency of long latencies and a secondary peak at 20 minutes, the longest allowed latency. Wake efficiencies (WE) (100% time asleep) were similarly distributed. Mean sleep latencies (SL) and mean WE were generally distributed more normally than the corresponding medians. Regression analysis showed that the MSLT variables best predicted by sleep-disordered breathing during the previous night were those based on WE. Effects were greatest for the first 1-2 naps. Whether the 4- or 5-nap MSLT can be shortened will depend on corroborating data from other labs. For now, mean WE appears to be the best measure of daytime sleep tendency. Regardless of which MSLT measure is used, sleep-disordered breathing, nocturnal sleep time, age, and gender together explain less than one-fourth of the variance found in the non-narcoleptic patients of a sleep disorders center. Much daytime sleepiness therefore remains unexplained.

Adult↗
PubMed1997

Circadian rest-activity rhythms in demented and nondemented older community residents and their caregivers.

OBJECTIVE: Disruptive nocturnal behaviors (DNBs) of older people often threaten the caregiving arrangements on which their community tenure depends. Dementing disorders are especially prone to result in disrupted sleep and agitated behaviors ("sundowning"). The objective here was to develop an objective correlate of DNBs, by which their severity and effects on caregivers can be measured. DESIGN: Quantitative comparison of subjective sleep and motor activity patterns in older people and their caregivers. It was hypothesized that older people with reported DNBs would be more motorically active at night than their caregivers. SETTING: Subjects' homes. PARTICIPANTS: Twenty-five demented and 18 nondemented older day-care participants and their paired caregivers. MEASUREMENTS: Older subjects and caregivers simultaneously kept daily sleep logs and recorded wrist motor activity every .5 minute for 9 days. A novel method was devised to identify and exclude from analysis periods when the activity monitor was not being worn. Such periods were common. Activity data were analyzed by computing hourly means and by fitting cosine models by least squares. RESULTS: Demented older people were not significantly more active at night than their caregivers, though group differences varied by time of night. They were significantly less active in the daytime than were their caregivers. Nondemented older people were significantly more active at night than their caregivers and were as active by day as their caregivers. The caregivers of demented and nondemented older people had similar rest-activity patterns. The mean amplitudes of cosine models were smaller in the older adults. Acrophases (peaks) fell between 2 and 3 pm and did not differ significantly among the groups. CONCLUSIONS: As a result of increased nighttime motor activity and decreased daytime activity, rest-activity rhythms were flatter in older adults than in caregivers. This was not explained fully by age and does not necessarily imply that the output of a circadian pacemaker was low. Decreased daytime activity may have resulted from deficient physical stimulation or frailty. Frailty may also explain why nighttime activity was not more elevated in the demented older people. Increased nighttime activity is probably explained by depression, sleep-schedule disturbances, restless legs, or other sleep disorders. Judging by their shared variations of activity, caregivers interacted mainly with the demented older people at bedtime and at rising time in the morning.

Aged↗
PubMed1997

Nocturnal interactions between community elders and caregivers, as measured by cross-correlation of their motor activity.

As the U.S. population ages, families must assume increasing responsibility for the care of elderly members. Disruptive nocturnal behaviors (DNBs) of elders, such as complaining and demanding help, may result in interactions with caregivers that threaten such arrangements. This study aimed to quantify such interactions by cross-correlating motor activity that was simultaneously recorded from the elders and caregivers. Forty-four elder-caregiver pairs reporting DNBs simultaneously kept sleep logs and wore activity recorders for 6 to 8 days. Day and night activity data were analyzed separately, because circadian variations would otherwise have overshadowed the elder-caregiver covariations of interest. An autoregressive model was fitted to each day and night data segment, and the data-model differences were used to calculate a cross-correlation function. Maximum significant values of the cross-correlation functions (rmax) exceeded .300 in 10 pairs of subjects. The unprocessed motor activity of these pairs looked so similar that rmax was interpreted as a measure of the subjects' interactions. The rmax was significantly larger for nighttime activity, especially in pairs who shared the same bed. It was smaller in pairs whose elders had high depression scores and in those with Parkinson's disease or related disorders. It was not affected by the presence of dementia. Analysis of the lags corresponding to significant values of rmax showed that, in cohabiting pairs, it was mainly the elders who initiated interactions. The findings provide unique, objective evidence that the night is a time of special difficulty for many caregivers of older Americans.

Aged↗
PubMed1994

Core body temperature in narcoleptic and normal subjects living in temporal isolation.

The aim was to detect abnormalities in the circadian temperature rhythms of narcoleptic patients, as evidence of abnormal circadian pacemaker function. Six narcoleptic patients and nine normal controls lived in a time-isolation laboratory for 18-22 days. Rectal temperature was measured every minute and modeled by mean waveforms and cosine functions, which have complementary advantages. In this study, the two types of models gave similar results: The levels, periods, amplitudes, and phases of the circadian temperature rhythms of patients and controls did not significantly differ--evidence against an abnormality of circadian pacemaker function in narcolepsy. The increases of temperature that normally follow main sleep periods were smaller in narcoleptic subjects, and narcoleptic naps, which were involuntary, were heralded and accompanied by small decreases of mean temperature.

Aged↗
PubMed1994

Regulation of sleep rate and circadian consolidation of sleep and wakefulness in an infant.

Observations of sleep and wakefulness were continuously made over an infant's first 6 months by Kleitman and Engelmann. Those data have been reanalyzed using a newly developed tool, fractional-time analysis, and two measures derived from it: 1) sleep rate, the rate at which the infant accumulated sleep; and 2) consolidation, the degree to which episodes of sleep and wakefulness were sustained and clustered. Changes in sleep rate and consolidation were independent and were attributed to separate underlying neural mechanisms. Consolidation increased over the 6-month course of development. This was explained by the development of circadian rhythmicity, which appeared during the 1st month as a free-running, endogenously generated rhythm in sleep-episode durations. Starting in the 2nd month, sleep rate was regulated, and it remained remarkably stable for weeks at a time. Sleep rate decreased over the 6-month period, perhaps because metabolic rate decreased as the infant grew. Short-term (weeks-long) changes in consolidation and sleep rate were explained by "beating" of the non-24-hour, endogenous sleep rhythm with direct effects of the 24-hour environment on sleep and wakefulness. Environmental stimuli eventually entrained the circadian pacemaker, bringing the consolidating periods of wakefulness and sleep into register with day and night. The infant was thereby efficiently exposed to periodic sensory and social stimuli, promoting normal neural development. A model of sleep-wake regulation based on independent mechanisms for circadian timing and sleep-wake regulation is proposed.

Circadian Rhythm↗
PubMed1994

Cardiac and respiratory activity in panic disorder: effects of sleep and sleep lactate infusions.

OBJECTIVE: This study examined cardiac and respiratory activity in panic disorder patients and healthy comparison subjects during sleep, when the effects of anxious cognition and expectancy set are minimized. METHOD: Heart rate, respiratory rate, end-tidal PCO2, and oxygen saturation were recorded for 11 panic disorder patients and 12 comparison subjects before and during sleep and before and after infusions of sodium lactate and a saline control. RESULTS: Panic disorder patients had higher oxygen saturations than comparison subjects before sleep onset and during sleep stages 0 and 2 before any infusions. The two groups did not differ on other respiratory variables and heart rate. Panic disorder patients responded to lactate infusions during stage 3-4 sleep with greater increases in heart rate and oxygen saturation, and possibly in respiratory rate and end-tidal PCO2, than comparison subjects. The saline control infusion had little effect. CONCLUSIONS: These findings suggest that panic disorder patients have greater cardiac and respiratory reactivity than healthy comparison subjects during sleep, when the influence of cognitive factors is minimal or absent.

Adolescent↗
PubMed1992

Daily sleep reports and circadian rest-activity cycles of elderly community residents with insomnia.

Sleep patterns were investigated in 29 insomniacs and 22 controls selected from a large sample of elderly residents of an urban community. According to sleep logs kept for a mean of 14.7 days, insomniacs took longer to fall asleep and stayed awake longer when they woke at night. In 14 insomniacs and 8 controls, wrist movements were monitored with a portable instrument. A circadian rhythm of motor activity was found in both groups, with some notable differences. Insomniacs were more active during periods of bedrest, and their mean daily rest-activity pattern--representing mean activity at equivalent times of day--was flatter. The mean level of activity over the entire experiment was similar in both groups. Insomnia in many elderly persons is thus associated with diffusion of activity over the 24-hr day, leaving bedrest periods only partially filled by rest or sleep.

Activities of Daily Living↗
PubMed1992

Age-related differences in recovery from simulated jet lag.

Six healthy young men and eight early middle-aged men were isolated from environmental time cues for 15 days. For the first 6-7 days (one or two nights adaptation, four nights baseline), their sleep and meals were scheduled to approximate their habitual patterns. Their daily routines were then shifted 6 hours earlier by terminating the sixth or seventh sleep episode 6 hours early. The new schedules were followed for the next 8 or 9 days. Important age-related differences in adjustment to this single 6-hour schedule shift were found. For the first 4-day interval after the shift, middle-aged subjects had larger increases of waking time during the sleep period and earlier termination of sleep than young subjects. They also reported larger decreases in alertness and well-being and larger increases in sleepiness, weariness and effort required to perform daily functions. The rate of adjustment of the circadian core temperature rhythm to the new schedule did not differ between groups. These results suggest that the symptoms reported by the middle-aged subjects may be due mainly to difficulty maintaining sleep at early times of the circadian day. The compensatory response to sleep deprivation may also be less robust in middle-aged individuals traveling eastbound.

Adolescent↗
PubMed1992

Cognitive and motor performance of narcoleptic and normal subjects living in temporal isolation.

Six unmedicated narcoleptic subjects and nine normal controls lived in a temporal isolation laboratory for 18-22 days. They were permitted to "free-run" for the last 9-13 days. Brief cognitive and motor performance tests were repeated on average six times per subjective day. They consisted of serial search, complex verbal reasoning tasks and manual dexterity of each hand. Only minor differences in performance were found between the narcoleptic subjects and controls. Narcoleptic subjects showed mild impairment of accuracy on the search task that could be explained by occasional lapses and an afternoon dip in performance. Narcoleptic subjects also tended to perform some tasks more slowly, but the group differences were not significant. Neither speed nor accuracy of performance of narcoleptic subjects decreased over the course of the experiment. By one standard of performance, therefore, all or nearly all of the sleep need of these subjects was met by the sleep they obtained in the laboratory. That amount, in turn, did not exceed the total sleep obtained by the normal controls. Significant time-of-day effects were found in narcoleptic subjects for speed of verbal reasoning (progressive slowing over the course of the day), manual dexterity (fluctuations in speeds) and accuracy of serial search (afternoon dip). These variations in performance could not be attributed to changes in core body temperature or to occurrences of naps or meals.

Adult↗
PubMed1991

High nocturnal body temperature in premenstrual syndrome and late luteal phase dysphoric disorder.

OBJECTIVE: Because women with late luteal phase dysphoric disorder (LLPDD) experience symptomatic affective states predictably, they can be studied to determine whether there are biological findings related solely to the clinically symptomatic state. The authors sought to answer the question, Does body temperature change with affective state? METHOD: The core body temperature and motor activity patterns of 10 women with premenstrual syndrome (PMS), six of whom also met criteria for LLPDD, and no other psychological or medical illness were compared to those of six women with chronic, noncyclic dysphoria and six asymptomatic comparison women at four phases of the menstrual cycle. RESULTS: The nocturnal temperatures of the women with PMS/LLPDD were significantly higher than those of the comparison subjects across the entire menstrual cycle, but there were no differences in nocturnal activity levels. The women with noncyclic dysphoria had a mean nocturnal temperature in the follicular phase as high as that of the women with PMS/LLPDD. The temperatures of all women were higher in the luteal phase than in the follicular phase. CONCLUSIONS: These findings suggest that in the future investigators should document menstrual cycle phase in all female subjects and, when studying body temperature, should carefully monitor symptomatic state in comparison subjects.

Adult↗