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Biomedical subjects

William R Lovallo

Publications and source records attributed to William R Lovallo.

At least 19 recordsLinked to original sources
PubMed2006

Cortisol responses to mental stress, exercise, and meals following caffeine intake in men and women.

Caffeine elevates cortisol secretion, and caffeine is often consumed in conjunction with exercise or mental stress. The interactions of caffeine and stress on cortisol secretion have not been explored adequately in women. We measured cortisol levels at eight times on days when healthy men and women consumed caffeine (250 mg x 3) and underwent either mental stress or dynamic exercise protocols, followed by a midday meal, in a double blind, placebo-controlled, crossover design. Men and women had similar cortisol levels at the predrug baselines, but they responded differently to mental stress and exercise. The cortisol response to mental stress was smaller in women than in men (p=.003). Caffeine acted in concert with mental stress to further increase cortisol levels (p=.011), the effect was similar in men and women. Exercise alone did not increase cortisol, but caffeine taken before exercise elevated cortisol in both men and women (ps<.05). After a postexercise meal, the women had a larger cortisol response than the men, and this effect was greater after caffeine (p<.01). Cortisol release in response to stress and caffeine therefore appears to be a function of the type of stressor and the sex of the subject. However, repeated caffeine doses increased cortisol levels across the test day without regard to the sex of the subject or type of stressor employed (p<.00001). Caffeine may elevate cortisol by stimulating the central nervous system in men but may interact with peripheral metabolic mechanisms in women.

Adult↗
PubMed2006

Recruitment of healthy participants for studies on risks for alcoholism: effectiveness of random digit dialling.

AIMS: To compare the effectiveness of two strategies for recruiting healthy research volunteers. METHODS: Demographic characteristics and recruitment costs of participants who completed a laboratory study examining risk factors for alcoholism recruited through random digit dialling (N = 11) and community advertisements (N = 102) were compared. RESULTS: Advertisement yielded a more representative sample [76% Caucasian, less well educated (M = 15.2 years, SEM = 0.2; P < 0.05), more equally divided by family history of alcoholism (43% FH- and 57% FH+), and lower in SES (M = 42.8, SEM = 1.3; P < 0.05)] and was more cost effective (72 dollars vs 2272 dollars per participant) than random digit dialling. CONCLUSIONS: Findings are relevant to alcohol researchers trying to determine the recruitment strategy that will yield the most representative sample at the lowest cost.

Adolescent↗
PubMed2006

Cortisol secretion patterns in addiction and addiction risk.

Addiction to alcohol or nicotine involves altered functioning of the brain's motivational systems. Altered functioning of the hypothalamic-pituitary-adrenocortical (HPA) axis may hold clues to the nature of the motivational changes accompanying addiction and vulnerability to addiction. Alcohol and nicotine show at least three forms of interaction with HPA functioning. Acute intake of both substances causes stress-like cortisol responses. Their persistent use may dysregulate the HPA. Finally, the risk for dependence and for relapse after quitting may be associated with deficient cortisol reactivity to a variety of stressors. The HPA is regulated at the hypothalamus by diurnal and metabolic signals, but during acute emotional states, its regulation is superseded by signals from the limbic system and prefrontal cortex. This top-down organization makes the HPA responsive to inputs that reflect motivational processes. The HPA is accordingly a useful system for studying psychophysiological reactivity in persons who may vary in cognitive, emotional, and behavioral tendencies associated with addiction and risk for addiction. Chronic, heavy intake of alcohol and nicotine may cause modifications in these frontal-limbic interactions and may account for HPA response differences in seen in alcoholics and smokers. In addition, preexisting alterations in frontal-limbic interactions with the HPA may reflect addiction-proneness, as shown in studies of offspring of alcohol- and drug-abusing parents. Continuing research on the relationship between HPA function, stress responsivity, and the addictions may yield insights into how the brain's motivational systems support addictions and risk for addictions.

Adaptation, Psychological↗
PubMed2006

Sex differences in the hemodynamic responses to mental stress: Effect of caffeine consumption.

The effect of caffeine on stress responses was compared in 25 men and 22 women in a 2-week placebo-controlled, double-blind, randomized crossover trial. On each week, participants abstained from all dietary sources of caffeine before undergoing a 6-h laboratory protocol under placebo or caffeine exposure followed by a 30-min mental stressor with blood pressure (BP) and cardiovascular hemodynamic assessments. On the placebo session, men and women showed a significant BP increase to stress, although women had significant cardiac responses whereas men had vascular responses. Caffeine ingestion before stress caused both men and women to have enhanced hemodynamic responses to the stressor associated with an increase in cardiac index and a drop in the peripheral resistance index. Caffeine enhances the cardiovascular fight-or-flight response pattern to stress in men and women.

Adult↗
PubMed2006

Working memory and decision-making biases in young adults with a family history of alcoholism: studies from the Oklahoma family health patterns project.

BACKGROUND: Alcohol misuse is more common in persons with a family history of alcoholism (FH+) than in those with no such history (FH-). Among FH+, behavioral disinhibition and male sex seem to signal the presence of an increased risk. METHODS: This study examined cognitive and behavioral characteristics of 175 nonabusing 18- to 30-year-olds, 87 FH+ and 88 FH-, who were further characterized by their degree of behavioral disinhibition using the Sociability scale of the California Personality Inventory. Working memory and decision making were tested using the Stroop Color-Word Test and the Iowa Gambling Task, a simulated card game. RESULTS: Persons with a family history of alcoholism who were behaviorally disinhibited displayed significantly greater interference on the Stroop task than the other subgroups. On the Iowa Gambling Task, FH+ males, but not the females, were significantly more attentive to financial gains than other subgroups, and they had greater consistency in their choice behaviors. CONCLUSIONS: Persons with a family history of alcoholism, in combination with behavioral disinhibition, appears to signal working memory deficits and in combination with male sex indicates an attraction to the rewarding aspects of a risk-taking challenge. These findings are not secondary to heavy exposure to alcohol or other drugs, but instead reflect intrinsic risk-related familial and personal characteristics of the subjects.

Adolescent↗
PubMed2005

Blunted hypothalamic-pituitary-adrenocortical axis responsivity to stress in persons with a family history of alcoholism.

Abstinent alcoholics show a blunted stress cortisol response that may be a consequence of drinking or a preexisting risk marker. We tested cortisol responses to psychological stress in 186 18-30 year-old, healthy social drinkers having no personal history of alcohol or drug dependence, 91 of whom had one or two alcoholic parents (FH+) and 95 having no family alcoholism for two generations (FH-). We predicted that, similar to alcoholic patients, the FH+ would have reduced stress cortisol responses that would be partially determined by their temperament characteristics, specifically antisocial tendencies as measured by the California Psychological Inventory. On a stress day, subjects performed continuous simulated public speaking and mental arithmetic tasks for 45 min, and on a control day they sat and rested for the same time period. The FH+ who were low in sociability had smaller cortisol responses than FH-, high-sociability persons (t=2.27, p=.02). These two groups were not different in diurnal cortisol secretion patterns or affective responses to the stressors. Persons with a familial risk for alcoholism who have more antisocial tendencies may have altered central nervous system responses to emotionally relevant social challenges. Disrupted cortisol stress responses may serve as a risk marker for the development of substance use disorders.

Adolescent↗
PubMed2005

Cardiovascular reactivity: mechanisms and pathways to cardiovascular disease.

Researchers in physiology, psychology, and medicine have held the idea that risk for cardiovascular disease is increased by exaggerated responses to stress. Some epidemiological evidence supports this view and shows that exaggerated blood pressure responses to stress add to disease prediction beyond that provided by standard risk factors. Most studies of reactivity and disease risk have taken a correlational approach to the reactivity-disease relationship. This paper presents a model of central nervous system control over peripheral response systems that provides a way of designating three sources of exaggerated stress reactivity that may vary across individuals. The top level in the model consists of the limbic system and prefrontal cortex as interacting areas that form psychological stress responses. These frontal-limbic interactions are a means of translating experiential and affective processes into bodily responses. The middle level consists of hypothalamus and brainstem areas that translate descending influences into bodily outputs. Activation levels in these structures can lead to enhanced reactivity to many forms of challenge. The final level consists of the peripheral effectors that create the response itself; altered effector function can be a source of enhanced reactivity. Study designs that involve both psychological and physiological challenges and that take account of self-reports of affect and activation provide a basis for separating these sources of responsivity. This organization may provide useful insights into the sources of stress reactivity that characterize specific groups at risk and allow inferences as to the source of the disease pathophysiology.

Animals↗
PubMed2005

Hemodynamic mechanisms underlying the incomplete tolerance to caffeine's pressor effects.

Blood pressure (BP) and cardiovascular hemodynamics were assessed at baseline and after caffeine administration in a 4-week, placebo-controlled, double-blind, randomized, crossover trial of caffeine tolerance formation. Half of the subjects developed tolerance to the pressor effect of caffeine, whereas the other half continued to show increases in BP after caffeine ingestion (F = 16.7, p <0.0001). In the subjects who did not develop tolerance, peripheral resistance increased incrementally as the daily dose of caffeine increased (F = 2.8, p = 0.05).

Adult↗
PubMed2005

Caffeine tolerance is incomplete: persistent blood pressure responses in the ambulatory setting.

BACKGROUND: Caffeine in dietary doses is a well-established pressor agent. Tolerance to this pressor effect occurs in only about half of regular consumers in acute laboratory tests. The clinical significance of this incomplete tolerance depends on whether the pressor effect is maintained throughout the day with repeated intake. Therefore, we examined the ability of a standard dose of caffeine (250 mg x 3) to maintain a blood pressure (BP) elevation during 18 hours of ambulatory BP monitoring (ABPM) after 5 days of regular daily intake of varying background doses. METHODS: Eighty-five men and women completed a four-week double blind, crossover trial. During each week, subjects consumed capsules totaling 0, 300, or 600 mg/day of caffeine in 3 divided doses. On day 6, they consumed capsules with either 0 or 250 mg at 9:00 am and 1:00 pm, in the laboratory, and again at 6:00 pm during ABPM. Tolerance was defined as a reduction in the diastolic BP response to two challenge doses given in the lab in response to increasing daily intake. Data were analyzed using multivariate repeated measures analysis of variance. RESULTS: BP responses to caffeine above those found on placebo-placebo (P-P) week were found for both tolerance groups when caffeine was consumed after a week of receiving a placebo. However, only the low tolerance group showed increases, above those found on P-P week, after 300 mg/day in systolic/diastolic BP during the waking hours (mean +/- standard error of the mean = 2.8 +/- 1.1, P = .01/2.2 +/- 0.9, P = .02) and in systolic BP during sleep (2.3 +/- 1, P = .03). CONCLUSIONS: Persistent elevations in BP occurring on a daily basis in some habitual caffeine consumers may hold clinical significance.

Adult↗
PubMed2004

Cardiovascular effects of caffeine in men and women.

Caffeine increases blood pressure (BP). In men, acute BP elevations after caffeine intake are due to an increase in vascular resistance, with no change in cardiac output. The hemodynamic effects of caffeine have not been studied in women. Accordingly, BP and hemodynamic responses to caffeine were measured in a double-blind trial comparing age-matched men and women at rest and during mental stress. Caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of brewed coffee) or placebo was given to separate groups of women (n = 21 and 21) and men (n = 16 and 19) (mean ages 29 and 27 years, respectively). BP, cardiac output, and vascular resistance were observed at rest, during a stressful public-speaking simulation, reading aloud, and recovery. Caffeine caused nearly identical systolic and diastolic BP elevations in women (4.5 and 3.3 mm Hg, respectively) and men (4.1 and 3.8 mm Hg, respectively). Men given caffeine versus placebo showed the expected elevation in vascular resistance throughout the remainder of the protocol (p <0.001), with no difference in cardiac output. In contrast, women responded to caffeine with increases in stroke volume (p <0.001) and cardiac output (p <0.001), with no difference in vascular resistance from women taking placebo. Men and women have similar BP responses to caffeine, but the BP responses may arise from different hemodynamic mechanisms. Women who consume a dietary dose of caffeine showed an increase in cardiac output, whereas men showed increased vascular resistance.

Adult↗
PubMed2004

Blood pressure response to caffeine shows incomplete tolerance after short-term regular consumption.

Caffeine acutely raises blood pressure (BP). The clinical significance of this effect depends on whether BP responses persist in persons who consume caffeine on a daily basis. Accordingly, the ability of caffeine to raise BP after 5 days of regular daily intake was tested in a randomized controlled trial. Individual differences in tolerance formation were then examined. Men (n=49) and women (n=48) completed a double-blind, crossover trial conducted over 4 weeks. During each week, subjects abstained for 5 days from dietary caffeine and instead used capsules totaling 0 mg, 300 mg, and 600 mg of caffeine per day in 3 divided doses. On day 6, in the laboratory, they used capsules with either 0 mg or 250 mg of caffeine at 9:00 am and 1:00 pm. Systolic/diastolic BP increases as a result of 250 mg of caffeine remained significant (P<0.006/0.001) at all levels of previous daily consumption. Individual difference comparisons found that although half the subjects had complete loss of systolic and diastolic BP responses to the challenge doses, the other half showed no loss in BP response, even after using 600 mg of caffeine per day for the previous 5 days (F >7.90, P <0.001). The sexes did not differ in degree of tolerance formation. Daily caffeine consumption failed to eliminate the BP response to repeated challenge doses of caffeine in half of the healthy adults who were tested. Caffeine may therefore cause persistent BP effects in persons who are regular consumers, even when daily intake is at moderately high levels.

Adult↗
PubMed2003

Cardiovascular responses to physical and psychological stress in female alcoholics with transitory hypertension after early abstinence.

BACKGROUND: Male alcoholic patients with acute withdrawal hypertension have shown exaggerated cardiovascular reactivity to stress after 3 to 4 weeks of abstinence, although resting blood pressures (BP) had returned to normal. Studies of this nature, however, have not been extended to women. METHODS: In this study, 32 alcohol-dependent women, abstinent for 4 weeks, were compared with 16 healthy controls on cardiovascular hemodynamics during rest and in response to 2 moderately aversive stressors: isometric handgrip and a speech task. The alcoholics were placed according to withdrawal BP into transitory hypertensive (tHT; n = 16; BP >or=140/90 mm Hg) and normotensive (NT; n = 16; BP <140/90 mm Hg) subgroups. RESULTS: During stress testing, the transitory hypertensive women had increased diastolic BP (p < 0.01), a higher peripheral resistance index (p < 0.05), and a reduced cardiac efficiency index (p < 0.03) relative to the normotensive and control subjects. CONCLUSIONS: This cardiovascular pattern suggests that both cardiac and vascular functions were altered adversely in the transitory hypertensives. In contrast to men examined in previous studies, the transitory hypertensive women had no exaggeration of BP reactivity, but instead showed sustained alterations of resting cardiovascular function in relation to chronic alcohol consumption. Although the pattern of cardiovascular dysregulation seems to be different in female alcoholics than in males, it is consistent with studies showing that cardiovascular effects in women are more severe than in men and emerge at a lower threshold level of chronic drinking.

Adult↗
PubMed2003

Altered affective modulation of the startle reflex in alcoholics with antisocial personality disorder.

BACKGROUND: Individual differences in neural circuitry that regulate emotional reactivity may be associated with alcoholism and antisocial personality disorder (ASPD), a common comorbid condition. The emotion-modulated startle reflex was used to investigate emotional reactivity among alcohol-dependent (AD) men with and without ASPD. METHODS: Sixty-two men were tested: (1) AD (n = 24), (2) AD-ASPD (n = 17), and (3) non-AD, non-ASPD controls (n = 21). Participants completed self-report instruments and clinical interviews and had eye-blink electromyograms measured in response to acoustic startle probes while viewing color photographs rated as affectively pleasant, neutral, and unpleasant. RESULTS: Startle blink magnitudes were larger during unpleasant as compared with pleasant slides for control and AD groups, resulting in significant linear trend effects (p < 0.001) and nonsignificant quadratic trend effects. In contrast, AD-ASPD did not show a significant difference in blink magnitude during unpleasant and pleasant slides and did not show a significant linear valence trend or quadratic trend effect (p > 0.6). Subjective valence and arousal ratings of the photographs were similar across groups. CONCLUSIONS: Adult male alcoholics with ASPD have abnormal emotional responsiveness to both pleasant and unpleasant stimuli relative to alcoholics without ASPD and to controls.

Acoustic Stimulation↗
PubMed2002

Adrenocortical stress responses and altered working memory performance.

This study examined stress cortisol responses and cognitive performance. We initially measured cortisol responses of 40 right-handed healthy male volunteers to counterbalanced mental arithmetic and public speaking stressors. We then examined the relationship between cortisol reactivity and dichotic listening and mental arithmetic performance. High cortisol responders made more errors and completed fewer mental arithmetic items than low reactors. On dichotic listening, high responders tended toward better performance in all conditions and to both ears. High responders showed better performance to the right ear in the forced right than in the nonforced condition, whereas no difference between these conditions was found in low responders. High cortisol responders may have an increased focus on sensory stimuli and a decreased allocation of resources to working memory tasks.

Adrenal Cortex↗
PubMed2002

Cortisol dysregulation and cognitive impairment in abstinent male alcoholics.

BACKGROUND: Alcoholics have impaired cortisol response to stress, indicating dysregulation in the extrahypothalamic systems responsible for activating cortisol secretion in response to stressor exposure. There is a growing literature indicating a relationship between hypothalamic-pituitary-adrenocortical axis activity and neurocognitive functioning. This study examined the hypothesis that dysregulation of the hypothalamic-pituitary-adrenocortical axis may be associated with some neuropsychological impairments in alcoholics. METHODS: Serum cortisol was obtained during cognitive testing and after exposure to cold pressor and mental arithmetic stress in 48 male alcoholics abstinent for 32 +/- 6.7 days and in 30 controls; cortisol was also obtained from 18 of the alcoholic patients during withdrawal. Neurocognitive tasks included the Wechsler Memory Scale and Wisconsin Card Sorting Test. Relationships among alcoholics' cognitive test scores, cortisol levels, and drinking practices were examined by correlation and regression analyses. RESULTS: Verbal memory deficits were more severe in alcoholics who had more withdrawals and ingested a higher typical quantity of alcohol during the prior year ( p< 0.05). Higher levels of cortisol during withdrawal, an index of withdrawal severity, were associated with more errors on the Wisconsin Card Sorting Test ( p< 0.005). As previously reported, the alcoholics had lower cortisol levels after stress compared with controls. Lower poststress cortisol levels were associated with poorer logical memory on the Wechsler Memory Scale and more errors on the Wisconsin Card Sorting Test ( p< 0.05). Among controls, memory deficits occurred only in relation to higher poststress cortisol levels. CONCLUSIONS: Poorer cognitive performance in alcoholics was related to more withdrawals, heavier alcohol consumption, and higher cortisol levels during a recent withdrawal. Alcoholics' cognitive impairment was also related to attenuated stress cortisol responses. Altered stress regulation of the hypothalamic-pituitary-adrenal axis should be studied further as a potential factor related to impaired cognitive function in recovering alcoholics.

Adult↗
PubMed2002

Neurological basis of deficits in affective prosody comprehension among alcoholics and fetal alcohol-exposed adults.

Affective prosody is a nonlinguistic aspect of language that conveys emotions and attitudes during discourse. In this study the neurological basis of affective prosodic comprehension (APC) dysfunction in alcoholics (ALC) and fetal alcohol-exposed adults (FAexp) was explored. Subjects were previously tested for APC by use of the Aprosodia Battery, including 9 right-brain-damaged and 10 left-brain-damaged subjects. ALC and FAexp subjects were significantly less accurate than control subjects in APC, and scored similarly to patients with focal brain lesions. The specific APC impairment found in ALC and FAexp may be a consequence of both callosal and right cortical dysfunction or damage.

Adult↗