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Biomedical subjects

P N Prinz

Publications and source records attributed to P N Prinz.

At least 37 records · Page 2Linked to original sources
PubMed1992

EEG markers of early Alzheimer's disease in computer selected tonic REM sleep.

All night sleep/wake EEGs were examined for diagnostic features sensitive to early Alzheimer's disease (AD) using computer automated techniques. Thirty-nine mild AD patients and 43 normal controls underwent 9 h of EEG recording in the sleep laboratory. All-night EEGs were screened for ideal, low artifact tonic REM sleep using autoregressive and power spectral techniques. The frequency spectra during tonic REM sleep revealed a significant shift towards slower wave forms in AD vs. control subjects. Beta (greater than 12 Hz) was reduced and theta and delta (2-8 Hz) increased in AD compared to control groups. This frequency shift was demonstrated by several analytic techniques, including binned spectral energies and unique zones in the frequency spectra. Discriminant analyses using optimal binned EEG variables correctly classified 74% of AD and 98% of control subjects, and unique zone scores correctly classified 92% of AD and 95% of control subjects, indicating that these sleep EEG changes are apparently predictive of AD status.

Aged↗
PubMed1992

Letter matching: effects of age, Alzheimer's disease, and major depression.

We compared Alzheimer's disease (AD) patients and Major Depressive Disorder (MDD), Aged normal, and Young normal controls on a letter-matching task designed to measure the time needed to access overlearned linguistic information in long-term memory. Name identity (NI) and physical identity (PI) reaction time and the NI-PI difference were compared for ADs, MDDs, and Aged normals and separately for Aged and Young normal groups. AD subjects had slower NI and PI reaction times and a bigger NI-PI difference than Aged normal and MDD subjects, suggesting that speed of access to overlearned letter-name information in long-term memory is slowed for ADs. There were no reliable differences between Aged normal and MDD subjects. Aged normals had slower NI and PI reaction times and a bigger NI-PI difference than Young normals, suggesting that the highly practiced operations needed to access letter-name information slow with age. A discriminant analysis was used to evaluate the usefulness of the "easy to perform" letter-matching task for diagnostic purposes. Ninety percent of normal and MDD subjects but only 68% of AD subjects were classified correctly.

Adult↗
PubMed1992

Sleep in Alzheimer's disease and the sundown syndrome.

Approximately 10% of the elderly population have a dementing illness that manifests itself clinically by significant cognitive deficits. Half of these individuals have Alzheimer's disease (AD), a progressive degeneration of cortical and subcortical neurons. Disturbances of sleep and the sleep-wake rhythm are a common clinical observation in AD, as is "sundowning," the onset or exacerbation of delirium during the evening or night. Here we describe the neurologic basis for the disturbed sleep of patients with AD, the phenomenology of that disturbance, and its implications. Further, we describe the prevalence, possible causes, and treatment of sundowning.

Aged↗
PubMed1991

EKG artifacts suppression from the EEG.

A method is proposed to identify and eliminate EKG artifacts from a single channel of EEG recordings. The method identifies the EKG as outlying data in the EEG. The algorithm may be applied universally to all EEG recordings.

Algorithms↗
PubMed1991

Sleep in Alzheimer's disease and other dementing disorders.

It is estimated that up to 10% of the elderly population have clinically significant cognitive deficits. The neuronal pathologies that underlie the dementing disorders cause both cognitive dysfunction and disturbances in normal sleep/wake patterns. Here we report the changes in sleep/wake patterns seen with increasing severity of Alzheimer's disease, probably the most common dementing disorder. In addition, studies examining sleep/wake patterns in a number of other dementing disorders are reviewed.

Alzheimer Disease↗
PubMed1991

Healthy elderly women and men have different entrained circadian temperature rhythms.

Body core temperature was measured in healthy elderly men and women under entrained conditions. Female subjects showed a larger amplitude and a higher peak temperature than male subjects. In addition, acrophase was advanced for females by an average of 49 minutes. Variability in acrophase was greater for males than females. This pattern of gender differences varies considerably from the pattern others have observed in young subjects, suggesting that aging may affect the circadian timing system of males and females differently.

Aged↗
PubMed1990

Sleep is undisturbed in elderly, depressed individuals who have not sought health care.

Sleep deficits are commonly found in geriatric depressed patients, particularly shortened rapid eye movements (REM) latency, disturbed sleep continuity, and decreased slow wave sleep (SWS). Here we report the sleep patterns of community volunteers responding to ads about memory loss and depression. The two groups, 24 geriatric-onset major depressive disorder (MDD) subjects with a minimal history of seeking treatment for depression and 24 gender- and age-matched control subjects, significantly differed from each other on only one measure of sleep--sleep latency; the MDD group showed a modest but significant shortening of latency to fall asleep. All other sleep/wake measures, including REM latency, temporal distribution of REM sleep across the night, SWS, and measures of nighttime wakefulness did not differ between groups. This lack of significant sleep disturbance suggests that the sleep deficits reported in many studies of major depression may be related to factors underlying treatment-seeking behaviors, physical health status, severity of the depression, or heterogeneity within the MDD population with some types seeking treatment and others not seeking it, rather than depressive state per se. The data indicate that community-dwelling healthy elderly individuals who have a diagnosed major depression but who have not actively sought health care do not necessarily manifest the sleep disturbances thought to be characteristic of major depressive illness.

Clinical Trials as Topic↗
PubMed1990

Sleep disturbances in patients with mild-stage Alzheimer's disease.

We examined the ability of sleep/wake measures to discriminate 45 control subjects from 44 mild Alzheimer's disease (AD) patients. Sleep fragmentation was observed as indicated by significant increases in time awake (37-52%) and number of awakenings (31-36%) during the night as compared to controls. Further, slow wave sleep (SWS) was significantly reduced (22%) in AD patients relative to controls. These findings are consistent with our earlier observations of increased wakefulness and decreased SWS in mild-moderate, moderate-severe, and severe stage AD patients. However, when we used these sleep/wake stage measures in discriminant analyses to classify the current AD subjects vs control subjects, the analyses failed to confirm our earlier high classification rate (90%). The present groups were discriminated at overall classification rates of only 63-67%. We conclude that while sleep/wake patterns are significantly disturbed in AD, this phenomenon is not diagnostically useful for discrimination of mild stage AD.

Aged↗
PubMed1990

Nighttime hypoxemia is increased in abstaining chronic alcoholic men.

Previously we reported that abstaining chronic alcoholic men demonstrated significantly more nighttime hypoxemia than a control group. Here, we report a replication employing a larger sample of abstaining chronic alcoholics and a more appropriate control group than that used in the previous study. Forty-seven males, 48.4 +/- 1.7 years of age (mean +/- SEM), reporting 24.8 +/- 1.5 years of heavy alcohol use, comprised the abstaining alcohol group. Thirty-five age- and weight-matched males, 50.3 +/- 1.7 years were the control group. The alcohol group had significantly more nighttime oxygen desaturations below 90% than did the control group (16.9 +/- 3.3 vs. 6.2 +/- 1.4, F = 7.8, p less than 0.01), with significantly higher percentages of individuals in the alcohol group manifesting more than 10 or 20 oxygen desaturations below 90%. Regression analyses within the alcohol group revealed that severity of alcohol abuse, but not age, body mass index, days abstinent, or smoking significantly predicted levels of nighttime hypoxemia. These results confirm our original observation of increased nighttime hypoxemia in abstaining chronic alcoholic men and suggest that long-term alcohol abuse may be a risk factor for development of sleep apnea.

Aging↗
PubMed1990

Relationship of alcohol abuse history to nighttime hypoxemia in abstaining chronic alcoholic men.

The nighttime blood oxygen saturation of 35 abstaining chronic alcoholic men was studied. Regression analyses indicated that various measures of alcohol abuse history (r = -.61, p less than .001) account for significant variance in nighttime hypoxemia. Age (r = -.39, p less than .05) and smoking history (r = .45, p less than .01) were less powerful predictors and both obesity and days abstinent from alcohol failed to correlate with hypoxemia. Possible mechanisms to explain the relationship between alcohol abuse history and hypoxemia are discussed. This and previously reported findings indicate that chronic alcohol abuse may predispose an individual to nighttime hypoxemia and be a risk factor for sleep apnea.

Alcoholism↗
PubMed1989

Dominant occipital (alpha) rhythm frequency in early stage Alzheimer's disease and depression.

The sinusoidal 8-13 Hz wave form that dominates in the occipital EEG record during relaxed wakefulness is known as alpha rhythm or dominant occipital rhythm. The frequency of this rhythm is known to decrease with normal aging with organic brain diseases. Here we report dominant occipital frequency (DOF) data for 41 early stage AD patients, 50 age-, sex- and health-matched control subjects and 22 subjects with major depressive disorder. DOF was assessed blindly for each subject from 10 or more samples during relaxed wakefulness in an all-night polysomnogram. Mean DOF was significantly lower in the AD (mean +/- S.D. was 8.24 +/- 1.04) than control group (9.48 +/- 0.57; F = 56, P less than 0.001). Mean DOF was also significantly lower in the depressed than control group (9.20 +/- 0.50 vs. 9.48, F = 5.0, P less than 0.05). In discriminant analyses, DOF achieved an overall correct classification rate of 77% for AD vs. control subjects, and 72% for AD vs. depressed subjects. These results indicate that DOF may be useful in identifying early stages of AD in healthy, drug-free populations.

Aged↗
PubMed1989

The WAIS-R profile: a diagnostic tool for Alzheimer's disease?

A diagnostic index, based on WAIS-R subtests, to identify patients with Dementia of the Alzheimer Type (DAT) and differentiate them from normal or depressed elderly was investigated. In a sample of 82 geriatric outpatient clinic patients who complained of memory loss, 22% of patients with probable DAT and 13% of nondemented patients obtained a positive profile. The occurrence of the profile in the two groups was not significantly different, nor were differences in education or severity of dementia found between subjects who did or did not obtain the profile. In a second sample of 173 elderly research volunteers, the profile occurred in 7% of DAT subjects, 10% of subjects complaining of memory loss who did not meet diagnostic criteria for DAT, 7% of nondemented major depressed subjects, and 7% of normal control subjects. Thus, the current investigation did not find the profile useful in differentiating DAT from other common disorders among elderly subjects. The authors conclude that a more comprehensive test battery remains the diagnostic tool of choice for differentiating DAT from other disorders.

Aged↗
PubMed1989

Alzheimer's disease. Sleep and sleep/wake patterns.

Significant changes in sleep/wake patterns, particularly loss of SWS and increased amount and frequency of nighttime wakefulness, apparently occur even at an early stage of the AD process. These disruptions of nighttime sleep increase in magnitude with increasing severity of dementia. While the REM sleep of early stage AD patients is relatively unaffected by the disease process, later stages of AD are marked by significant losses of REM sleep and perhaps more importantly the breakdown of the sleep/wake circadian rhythm with significant amounts of sleep occurring during the day. This daytime sleep is of poor quality however, consisting almost exclusively of stages 1 and 2 sleep and does not compensate for the nighttime losses of SWS and REM sleep experienced by AD patients. These findings clearly support the clinical observations and anecdotal reports of sleep disturbance in AD patients. It is of interest to note that sleep is disrupted quite early in the disease process. In our study of early stage AD patients all were community dwelling and had relatively mild cognitive impairment (average MMS scores of 22.7). Despite this, significant increases in frequency and duration of awakening from sleep and reductions of SWS were observed in these patients. These findings indicate that when a patient is suspected of having AD it may be worthwhile as part of the evaluative and diagnostic process to caution both the patient and the patient's family that they might expect to see significant changes in sleep/wake patterns even though the patient's level of day-to-day functioning may still be high. It is also important to consider warning AD patients' families that as the disease progresses they should expect to see not only a worsening of nocturnal sleep quality but a breakdown of the circadian sleep/wake rhythm and an increase in daytime napping behavior by the patient. Families need to be encouraged to try and minimize the napping behavior of the patient in an effort to consolidate sleep into the night. This may have the effect of somewhat attenuating the amount of nocturnal disruption of sleep that accompanies progression of the disease.

Aged↗
PubMed1988

Successful recruitment of elderly community-dwelling subjects for Alzheimer's disease research.

One hundred seventy-four healthy community-dwelling subjects were recruited for a research project investigating Sleep/EEG measures as biological markers for early-stage Alzheimer's Disease (AD). All subjects were age 55 or older. The subjects were divided into four groups: 46 subjects were diagnosed as having mild, uncomplicated AD, 31 had memory problems but did not meet the research criteria for AD, 43 had uncomplicated major depressive disorder, and 54 were normal controls. Male depressives and mild AD subjects were the groups most difficult to recruit. The ratio of initial inquiries from potential subjects to final study participants in all groups combined was 9 to 1. Successful recruiting strategies for each study group are discussed. News announcements and referrals from other AD researchers accounted for the greater number of study participants.

Advertising↗
PubMed1987

History of chronic alcohol abuse is associated with increased nighttime hypoxemia in older men.

The all-night blood oxygen saturations (SaO2) of 19 older abstaining male alcoholics and 19 healthy age-matched controls were recorded. The alcohol group had significantly lower nighttime mean and minimum oxygen saturations, significantly greater absolute (mean-minimum) SaO2 desaturations, and significantly more desaturations below 90% compared with the control group. Additionally, the alcohol group had significantly more individuals with nighttime SaO2 means below 95% and nighttime SaO2 minimums below 90%. Finally, within the alcohol group, alcohol history was found to significantly correlate with nighttime mean and minimum SaO2 and absolute SaO2 desaturation. This preliminary study finds evidence that chronic alcohol abuse may predispose an individual to nighttime hypoxemia, and, inferentially, to sleep apnea. However, the effect is modest and it will need to be confirmed in larger, more carefully controlled studies.

Age Factors↗
PubMed1986

Functional decline in the early stages of Alzheimer's disease.

At present most reports of functional decline in patients with Alzheimer's Disease (AD) are anecdotal, and few studies have objectively documented the course of the disease. This is a report of a 2-year follow-up of 15 AD patients characterized by mild functional impairment, and 22 age-, sex-, and education-matched control subjects. In a previous cross-sectional study of these 37 subjects and 16 AD patients with moderate functional impairment, we found that measures of memory and attention deficits accounted for much of the impairment observed in functional competence. The current longitudinal study found that these same initial assessments could be used to predict functional decline in the 15 mildly impaired patients. These patients were observed to decline to levels similar to those of the 16 moderate patients. In contrast, the control subjects exhibited little decline during the same period. These results both affirm that it is possible to diagnose AD in its mild form and demonstrate the validity of the initial diagnosis.

Aged↗
PubMed1985

Somatomedin-C levels in healthy young and old men: relationship to peak and 24-hour integrated levels of growth hormone.

We investigated the relationship between growth hormone secretion and somatomedin levels as a function of age in normal healthy men. There was a substantial decrease with age in somatomedin levels from 0.95 +/- 0.06 (M +/- SEM) units/ml in young (23 to 27 years) men to 0.68 +/- 0.07 in old (58 to 82 years) men. The blood samples were taken throughout a 24-hour period, so it was possible to analyze the data for correlations between average somatomedin levels and various aspects of growth hormone secretion. There was a significant correlation of somatomedin level with the 24-hour integrated growth hormone level, and a nearly significant correlation with the sum of the highest three peaks, but no correlation with the highest nighttime peak or the basal level of growth hormone. These lower blood levels of somatomedin in the aged may be responsible, at least in part, for the catabolic effects on muscle and bone frequently associated with aging.

Adult↗