Menstrual cycle phase is a potential confound in psychophysiology research

Electroencephalography Coherence, Memory Vividness, and Emotional Valence Effects of Bilateral Eye Movements During Unpleasant Memory Recall and Subsequent Free Association: Implications for Eye Movement Desensitization and Reprocessing

This study examined the effects of bilateral stimulation during unpleasant memory recall followed by free association, similar to Phase 4 of EMDR therapy. Forty-six female nonpatients were randomly assigned to one of three conditions: bilateral eye movements (BEMs), eye fixation with background movements (BDM), or eye fixation (Dot) control, each while recalling a moderately unpleasant memory and each followed by free association to the memory. Electroencephalography recordings were conducted on these participants during the 1-minute free association of the original memory after each of five administrations of the conditions. Results revealed only trend increases in Beta interhemispheric coherence following BEMs. However, statistically significant increases in Right Frontal Theta and Beta intrahemispheric coherences were found following BEMs, with similar trend increases for Left Frontal Theta and Beta and for Right Frontal Gamma. Cortical electrode maps are presented for these Beta coherence effects. Ratings of imagery vividness and emotional valence were collected after each set of eye movements plus free associations and showed a significant decrease across all conditions. Results are discussed within the context of a proposed integrated 2-stage cortical coherence model. Suggestions are made for future research, including investigation of possible implications for treatment of traumatic brain injury.

Cardiovascular reactivity to mental stress: relationship with menstrual cycle and gender

The purpose of the present study was to determine the fluctuation in cardiovascular reactivity to mental stress during the menstrual cycle by comparing heart rate variability (HRV), and other physiological and psychological data in females with those in males. Cardiovascular reactivity to two mental tasks was measured in 14 females during the follicular and luteal phase of menstruation over two menstrual cycles. The same tasks were subsequently given to a matched pair of males (N=14), at the same intervals as their corresponding females. Heart rate, blood pressure and HRV were used as indices of cardiovascular reactivity. Subjective mental workload was measured at the end of each task. Power spectral analysis of HRV showed that the high frequency (HF) component in HRV decreased more during the luteal phase than the follicular phase. The low frequency (LF) component in HRV and the LF/HF ratio in the luteal phase were significantly higher than that in the follicular phase. The LF component and the LF/HF ratio were significantly lower in females than in males; conversely, the HF component was significantly higher in females than in males. Neither significant effects of menstrual cycle, gender and mental stress nor any significant interactions were found for mental workload. These findings indicate that sympathetic nervous activity in the luteal phase is significantly greater than in the follicular phase whereas parasympathetic nervous activity is predominant in the follicular phase. The results also suggest that predominance of sympathetic nervous activity in males compared with a dominant parasympathetic nervous activity in females.

Cardiovascular functioning during the menstrual cycle

Variations in cardiovascular functioning during the 'normal' menstrual cycle have been little researched. Resting-blood pressures, resting-heart rate, rate-pressure product (RPP) and a derived index of fitness (Schneider Index) were monitored throughout natural, hormonally defined menstrual cycles. Volunteers were 26 women (20-48 years) who had regular (25-35 days) cycles. Their blood pressures and heart rate (at rest and according to Schneider's protocol) were measured at the same time daily (Monday-Friday) for 5 weeks. Daily, early morning-urine samples were assayed for sex hormones enabling accurate definition of cycle phase for each woman. Resting systolic-blood pressure was significantly higher in the ovulatory phase (P < 0.05) than in the follicular or luteal phases, but resting-diastolic pressures did not differ significantly between phases. Resting-heart rate was significantly higher in both ovulatory (P < 0.01) and luteal (P < 0.01) phases than in the menstrual and follicular phases. The Schneider Index was higher during the follicular phase than during the ovulatory (P < 0.005) or luteal (P < 0.01) phases, the RPP was higher during the ovulatory phase than during the bleeding (P < 0.05) and follicular (P < 0.005) phases. These findings provide a pattern of menstrual cycle-related variation in cardiovascular functioning that can be related to established actions of the ovarian steroids.

Discrimination of tone durations across the menstrual cycle

Discrimination of tone duration was studied as a function of menstrual cycle phase. In three phases of their menstrual cycle, 12 women compared the durations of 64 pairs of tones. They discriminated the tone durations least well in the premenstrual phase and tended to speed up their responding over sessions. In contrast, a control group of 12 men tended to improve their performance over sessions while response time remained constant.

Hemodynamic and sympathetic nervous system responses to stress during the menstrual cycle

In this study, the impact of menstrual cycle phase on hemodynamic and sympathetic nervous system responses was examined during exposure to a battery of laboratory stressors. Participants were 40 healthy premenopausal women, aged 26 to 51. Impedance cardiography was used to measure stroke volume, heart rate, and cardiac output. Systemic vascular resistance was derived on the basis of concurrently recorded blood pressure and cardiac output. The menstrual cycle's effect on the sympathetic nervous system response was explored by evaluating plasma catecholamine responses during stress. In luteal compared with follicular subjects, systemic vascular resistance was significantly lower during all stress tasks (P < 0.03). Catecholamine responses were also significantly lower in luteal subjects (P < 0.004). The results suggest that the sympathetic nervous system may respond to stress differently during different phases of the menstrual cycle. This finding has implications for understanding "whitecoat hypertension" in women, and highlights the need to measure blood pressure during several office visits. Perhaps high blood pressure readings recorded during the follicular phase should be reexamined during the luteal phase before considering pharmacologic intervention.

Cardiovascular and mood responses to quantified doses of cigarette smoke in oral contraceptive users and nonusers

Previous research suggests that the female sex hormones may moderate cardiovascular and mood responses to cigarette smoking and abstinence. To test this possibility, acute effects of cigarette smoking on cardiovascular reactivity and mood were examined in 12 oral contraceptive users and 12 nonusers across two menstrual phases (early and late cycle). After overnight deprivation, each participant attended two sessions in which they first sham-smoked and then smoked two standard cigarettes, via a quantified smoke delivery system. Oral contraceptive users exhibited larger cigarette smoking-induced increases in heart rate compared with nonusers. In addition, cigarette smoking-induced cardiovascular changes varied with both the phase of the menstrual cycle and oral contraceptive use. No menstrual phase-dependent effects were observed for tobacco withdrawal symptoms, premenstrual symptoms, or moods prior to smoking. Cardiovascular hyperreactivity to cigarette smoke in oral contraceptive users may help explain the mechanisms by which smoking and oral contraceptive use contribute to an elevated risk for coronary heart disease.

Variations Across the Menstrual Cycle in EEG Activity During Thinking and Mental Relaxation

Abstract Previous studies have indicated: (1) peak performance on tests of divergent creative thinking during the ovulatory phase of the menstrual cycle; (2) compared to convergent analytical thinking, divergent thinking was found to be associated with a distinctly increased dimensional complexity of ongoing EEG activity. Based on these findings, we hypothesized that cortical information processing during the ovulatory phase is characterized by an increased EEG dimensionality. Each of 16 women was tested on 3 occasions: during the ovulatory phase, the luteal phase, and menses. Presence of the phases was confirmed by determination of plasma concentrations of estradiol, progesterone, and luteinizing hormone. The EEG was recorded while the women performed: (1) tasks of divergent thinking; (2) tasks of convergent thinking; and (3) during mental relaxation. In addition to EEG dimensional complexity, conventional spectral power analysis was performed. Behavioral data confirmed enhanced creative performance during the ovulatory phase while convergent thinking did not vary across cycle phases. EEG complexity was higher during divergent than convergent thought, but this difference remained unaffected by the menstrual phase. Influences of the menstrual phase on EEG activity were most obvious during mental relaxation. In this condition, women during the ovulatory phase displayed highest EEG dimensionality as compared with the other cycle phases, with this effect being most prominent over the central and parietal cortex. Concurrently, power within the alpha frequency band as well as theta power at frontal and parietal leads were lower during the luteal than ovulatory phase. EEG results indicate that task demands of thinking overrode effects of menstrual cycle. However, with a less demanding situation, an ovulatory increase in EEG dimensionality became prominent suggesting a loosening of associative habits during this phase.

Comparing levels of cocaine cue reactivity in male and female outpatients

Thirty-eight female and 26 male cocaine-dependent outpatients were exposed to cocaine cues in a laboratory setting. Stimuli consisted of an audiotape of patients discussing cocaine use, a videotape of simulated cocaine preparation and use, and the handling of cocaine paraphernalia. Overall, the stimuli produced significant decreases in skin temperature and skin resistance, and significant increases in heart rate, self-reported drug states (high, craving, and withdrawal), and self-reported negative moods. Females were more likely to report increased craving in response to the cues than males, but there were no other gender differences in any of the responses. Levels of reactivity in females were comparable to the results of previous studies with all male samples. These results support the use of a constant set of cues in future treatment studies employing gender-balanced patient samples.

Effects of menstrual phase on reactivity to nicotine

The possible impact of menstrual phase upon reactivity to nicotine was investigated in 12 healthy women smokers. Controlled doses of nicotine were administered via an intranasal aerosol delivery device to overnight-deprived women smokers in four hormonally verified menstrual phases. Physiological, biochemical, and subjective measures were collected. Cycle-related symptomatology differed significantly across phase, with lowest values during the mid-follicular phase. No significant differences were found for baseline variables, including withdrawal measures. Nicotine increment was stable across phase, confirming reliability of the dosing method. No significant menstrual phase differences were found for physiological, subjective, or biochemical responses to nicotine. Pending investigations conducted over longer intervals, in a wider variety of subjects; findings suggest that for this type of study, complex strategies to control for menstrual-cycle phase effects may be unnecessary.

Cardiovascular, endocrine, and receptor measures as related to sex and menstrual cycle phase

OBJECTIVE

The present study was undertaken to elucidate possible mechanisms underlying sex differences in cardiovascular measures or reactivity to challenge. Because there is vastly diverging literature on the issue, we tried to control for endocrine and psychological factors, which might contribute to some of the apparent discrepancies.

METHODS

Blood pressure, heart rate, adrenaline, and noradrenaline in women (N = 24) and men (N = 14) were examined during baseline and challenge (Stroop Test and Cold Face Test). Adrenoceptor density on lymphocytes (beta 2) and platelets (alpha 2) were determined to examine possible sex differences in underlying cardiovascular mechanisms. Gender effects were controlled by assessing gender role orientation and task appraisal. Women were tested during either the follicular (N = 12) or the luteal (N = 12) phase of the menstrual cycle (verified by estradiol, progesterone, and luteinizing hormone).

RESULTS

Follicular and luteal phase women did not differ in any parameter except progesterone. We observed sex-related differences in absolute levels of physiological parameters, the male group having higher systolic blood pressure levels, higher adrenaline plasma concentrations, and significantly more alpha 2-adrenergic receptors. Both challenges elicited pronounced cardiovascular and endocrine responses. Men and women did not differ in response magnitude, in task appraisal, or gender role orientation.

CONCLUSIONS

The assumption that female sex hormones reduce reactivity to challenge is not supported by our data. The frequently reported male/female differences in reactivity may be caused by an interaction of gender and task characteristics.

How many sphygmomanometric cuff inflations are necessary to obtain a hemodynamic baseline?

The purpose of this study was to determine the minimum number of consecutive blood pressure cuff inflations required to obtain seated stable resting baseline measurements of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP). Sixty male college students aged 18 to 31 years volunteered as study subjects. Thirteen observations of HR, SBP, DBP, and MAP were recorded at 90-second intervals for each subject using a Critikon-Dinamap monitor. Stable readings for SBP and MAP were obtained in 6.5 minutes or 3 to 5 cuff inflations in the population tested. Using this procedure, additional age- and gender-specific norms could be established for normal and hypertensive subjects. Knowing the approximate quantity and frequency of blood pressure cuff inflations needed to generate baseline minimum measurements of HR, SBP, DBP, and MAP will be helpful in studies of cardiovascular reactivity, as well as for clinical and psychophysiologic treatment of hypertension.

Diurnal sleep/wake-related immune functions during the menstrual cycle of healthy young women

Animal and human studies have related the sleeping/waking brain to the immune system. Because women are more susceptible to certain immunological illnesses, and sex steroids regulate immune functions, it was investigated whether the diurnal sleep/wake pattern of aspects of cellular immune functions and interleukin-1 (IL-1) and IL-2-like activities differed during low and high progesterone phases of the menstrual cycle. Eleven healthy women, mean age 24 y, were assessed over 24 h with serial venous blood samples. Peripheral blood monocytes were assayed for mitogen responses, i.e. phytohemagglutin (PHA) and pokeweed (PWM) and natural killer (NK) cell activities. Plasma was assayed for IL-1 and IL-2-like activities, cortisol and progesterone. Data were standardized by Z transformation and analysed by repeated-measures analysis of variance by comparing high (N = 5) vs. low (N = 6) progesterone phases. During the high progesterone phase, delayed slow-wave sleep (SWS) onset time and reduced amount of SWS was accompanied by a delay in the decline of NK cell activity, but rise in PHA activity following sleep onset. With the low progesterone phase, the pattern was similar to men with an early sleep decline in NK cell and late sleep rise in PHA activities. PWM rose during the night and plasma IL-1-like activity peaked during midday and during nocturnal sleep irrespective of the amount of progesterone. Slow-wave sleep and sleep-related NK cell and PHA activities differed over the menstrual cycle, but not PWM response. Increases in plasma IL-1 functions during midday and night are consistent with predisposition to sleepiness during these times.

Autonomic responses of women with parental hypertension. Effects of physical activity and fitness

We studied the moderating effects of cardiorespiratory fitness and physical activity on heart rate and blood pressure responses to psychophysiological stressors and the carotid-cardiac baroreflex in young normotensive women with a parental history of hypertension (n = 31). Testing occurred during the follicular menstrual phase. Subjects were divided into high versus moderate (46.6 +/- 6.5 versus 35.9 +/- 1.9 mL.kg-1.min-1) VO2peak and high versus moderate (1217.7 +/- 98.4 versus 1015.5 +/- 49.4 J.kg-1.wk-1) physical activity groups. The groups did not differ in heart rate or blood pressure responses to mental arithmetic or the cold-face test. However, the highly fit women had longer maximal R-R intervals compared with the moderately fit women when the carotid-cardiac baroreflex was stimulated by negative pressures applied to the neck during resting conditions (P < .01). The carotid-cardiac baroreflex was attenuated during mental arithmetic compared with rest in both the moderately fit and moderately active women but not in the highly fit and highly active groups. We find no evidence that aerobic fitness reduces sympathetic responses to laboratory stressors in young women with parental hypertension. Our findings are consistent with greater parasympathetic tone during sympathetic challenge for the highly fit and highly active subjects. Clarification of autonomic balance during carotid baroreflex stimulation at rest and during sympathetic challenge after exercise training would provide important information regarding mechanisms that regulate cardiovascular responses to autonomic challenge in women at risk for hypertension.

Hemodynamic stress responses in men and women examined as a function of female menstrual cycle phase

Fifteen men and 11 normally ovulating women were each tested twice for cardiovascular stress reactivity, cognitive/behavioral performance, and mood during a variety of stressors. Each women was tested during both the follicular and luteal phase of her menstrual cycle, with men matched for number of days between testing. Although the genders did not differ in blood pressure reactivity during either phase of the cycle, during both phases of the menstrual cycle women exhibited greater heart rate reactivity and tended towards greater cardiac index increases, greater pre-ejection period decreases, and lesser vascular tone relative to men. Additionally, the menstrual cycle was observed to influence gender differences in stroke volume index responses. Specifically, stroke volume index responses for women were significantly greater in their luteal versus follicular phase resulting in a marginally significant pattern whereby women's stroke volume index responses were greater than men's luteally but less than men's follicularly. Men and women also differed in cognitive performance and mood assessment during the tasks, but the majority of these differences were unaffected by the menstrual cycle.

Family history of hypertension and cardiovascular changes during high and low affect provocation

The present study investigated whether subjects with a positive family history of hypertension would display differential responses in blood pressure and heart rate across different laboratory tasks. We also wanted to know whether subjects would display stable within-subject responses across different laboratory tasks. Twenty-three family history positive subjects and 23 with a negative family history participated in three tasks: 1) mental arithmetic, 2) a conversation about the weather (low affect task), and 3) a conversation about a recent upsetting, interpersonal event (high affect task). Positive family history was associated with elevated diastolic resting blood pressure and greater diastolic responsivity overall. For both groups, arithmetic was associated with the greatest heart rate changes, whereas the distressing conversation was accompanied by the greatest diastolic blood pressure response. Stability of cardiovascular activation across different tasks was present only for heart rate; it was weak for diastolic blood pressure, and completely absent for systolic blood pressure.