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Biomedical subjects

C L Hart

Publications and source records attributed to C L Hart.

At least 19 recordsLinked to original sources
PubMed2007

How many cases of Type 2 diabetes mellitus are due to being overweight in middle age? Evidence from the Midspan prospective cohort studies using mention of diabetes mellitus on hospital discharge or death records.

AIMS: To relate body mass index (BMI) in middle age to development of diabetes mellitus. METHODS: Participants were 6927 men and 8227 women from the Renfrew/Paisley general population study and 3993 men from the Collaborative occupational study. They were aged 45-64 years and did not have reported diabetes mellitus. Cases who developed diabetes mellitus, identified from acute hospital discharge data and from death certificates in the period from screening in 1970-1976 to 31 March 2004, were related to BMI at screening. RESULTS: Of Renfrew/Paisley study men 5.4%, 4.8% of women and 5% of Collaborative study men developed diabetes mellitus. Odds ratios for diabetes mellitus were higher in the overweight group (BMI 25 to < 30 kg/m(2)) than in the normal weight group (BMI 18.5 to < 25 kg/m(2)) and highest in the obese group (BMI >or= 30 kg/m(2)). Compared with the normal weight group, age-adjusted odds ratios for overweight and obese Renfrew/Paisley men were 2.73 [95% confidence interval (CI) 2.05, 3.64] and 7.26 (95% CI 5.26, 10.04), respectively. Further subdividing the normal, overweight and obese groups showed increasing odds ratios with increasing BMI, even at the higher normal level. Assuming a causal relation, around 60% of cases of diabetes could have been prevented if everyone had been of normal weight. CONCLUSIONS: Overweight and obesity account for a major proportion of diabetes mellitus, as identified from hospital discharge and death records. With recent increases in the prevalence of overweight, the burden of disease related to diabetes mellitus is likely to increase markedly. Primordial prevention of obesity would be a major strategy for reducing the incidence of diabetes mellitus in populations.

Age Factors↗
PubMed2006

Obesity and use of acute hospital services in participants of the Renfrew/Paisley study.

BACKGROUND: Because overweight and obesity are associated with comorbidities, increasing levels of overweight and obesity may impact on hospital use. METHODS: Body mass index (BMI) in middle age was related to acute hospital use in 7036 men and 8327 women from the Renfrew/Paisley prospective cohort study in Scotland. Participants in this general population study were examined between 1972 and 1976 when aged 45-64 years. Acute hospital admissions and bed days per 1000 person-years were calculated by the World Health Organization BMI categories in the follow-up period to 31 March 2004. RESULTS: Underweight and normal weight men had lower-than-expected admission rates, and overweight and obese men had higher-than-expected admission rates. Obese men had higher-than-expected bed day rates. For women, there was a U-shaped relationship with admission rate, with normal weight women having the lowest admission rate and underweight and obese women having similar high rates. Underweight and obese women had higher-than-expected bed day rates. CONCLUSIONS: Participants who were obese in midlife had more-than-expected acute hospital admissions and in particular more bed days. With levels of obesity increasing since this study was started in the 1970s, if these patterns persist, there may be increasing demand on health service resources.

Body Mass Index↗
PubMed2006

A population study of the long-term consequences of Rose angina: 20-year follow-up of the Renfrew-Paisley study.

OBJECTIVE: To examine the long-term cardiovascular consequences of angina in a large epidemiological study. DESIGN: Prospective cohort study conducted between 1972 and 1976 with 20 years of follow-up (the Renfrew-Paisley Study). SETTING: Renfrew and Paisley, West Scotland, UK. PARTICIPANTS: 7048 men and 8354 women aged 45-64 years who underwent comprehensive cardiovascular screening at baseline, including the Rose Angina Questionnaire and electrocardiography (ECG). MAIN OUTCOME MEASURES: All deaths and hospitalisations for cardiovascular reasons occurring over the subsequent 20 years, according to the baseline Rose angina score and baseline ECG. RESULTS: At baseline, 669 (9.5%) men and 799 (9.6%) women had angina on Rose Angina Questionnaire. All-cause mortality for those with Rose angina was 67.7% in men and 43.3% in women at 20 years compared with 45.4% and 30.4%, respectively, in those without angina (p<0.001). Values are expressed as hazards ratio (HR) (95% confidence interval (CI). In a multivariate analysis, men with Rose angina had an increased risk of cardiovascular death or hospitalisation (1.49 (1.33 to 1.66), myocardial infarction (1.63 (1.41 to 1.85)) or heart failure (1.54 (1.13 to 2.10)) compared with men without angina. The corresponding HR (95% CI) for women were 1.38 (1.23 to 1.55), 1.56 (1.31 to 1.85) and 1.92 (1.44 to 2.56). An abnormality on the electrocardiogram (ECG) increased risk further, and both angina and an abnormality on the ECG increased risk most of all compared with those with neither angina nor ischaemic changes on the ECG. Compared with men, women with Rose angina were less likely to have a cardiovascular event (0.54 (0.46 to 0.64)) or myocardial infarction (0.44 (0.35 to 0.56)), although there was no sex difference in the risk of stroke (1.11 (0.75 to 1.65)), atrial fibrillation (0.84 (0.38 to 1.87)) or heart failure (0.79 (0.51 to 1.21)). CONCLUSIONS: Angina in middle age substantially increases the risk of death, myocardial infarction, heart failure and other cardiovascular events.

Age Distribution↗
PubMed2006

Effect of socioeconomic deprivation on the population risk of incident heart failure hospitalisation: an analysis of the Renfrew/Paisley Study.

BACKGROUND: There are few data describing the effect of socioeconomic deprivation on the risk of developing heart failure (HF). AIMS: To examine the relationship between socioeconomic deprivation and hospitalisation with HF over 20 years. METHODS: Between 1972 and 1976, 15,402 individuals, aged 45-64 years, residing in two towns in Scotland, underwent cardiovascular screening. We report hospitalisations with HF over the subsequent 20 years according to Carstairs deprivation category and Social Class. RESULTS: Following screening, 628 men and women (4.1%) were hospitalised with a primary diagnosis of HF. There was a gradient in the risk of HF hospitalisation with increasing socioeconomic deprivation (P=0.003). Of the most deprived individuals, 6.4% were hospitalised for HF compared to 3.5% of the most affluent group. Cox-proportional Hazard models showed that independent of age, sex and baseline risk factors for cardio-respiratory status, greater socioeconomic deprivation increased the risk of HF admission (P<0.001, overall). The adjusted risk of admission for HF was 39% greater in the most versus least deprived subjects (RR 1.39 95% CI 1.04-2.01; P=0.04). CONCLUSION: These data show a link between social deprivation and the risk of developing HF, irrespective of baseline cardio-respiratory status and cardiovascular risk factors.

Female↗
PubMed2005

Long-term cardiovascular consequences of obesity: 20-year follow-up of more than 15 000 middle-aged men and women (the Renfrew-Paisley study).

AIMS: To examine the long-term cardiovascular consequences of obesity and project the cardiovascular consequences of the recent increase in prevalence of obesity. METHODS AND RESULTS: Between 1972 and 1976, 15 402 individuals aged 45-64, living in two towns in the west of Scotland underwent comprehensive cardiovascular screening. We analysed all deaths and hospitalizations for cardiovascular reasons occurring over the subsequent 20 years according to baseline body mass index (BMI) category. Compared with normal weight individuals (BMI 18.5-24.9), obesity (BMI > or =30) was associated with an increased adjusted risk of coronary heart disease (hazard ratio for death or hospital admission: 1.60, 95% CI 1.45-1.78), heart failure (2.09, 1.68-2.59), stroke (1.41, 1.21-1.65), venous thrombo-embolism (2.29, 1.60-3.30), and atrial fibrillation (1.75, 1.17-2.65). Obesity was associated with nine additional cardiovascular deaths and 36 additional cardiovascular hospital admissions for every 100 affected middle-aged men over the subsequent 20 years (seven deaths and 28 admissions in women). Assuming no change in cardiovascular risk profile and outcomes related to obesity, the increase in prevalence in 1998, when compared with 1972, is projected to lead to an additional four cardiovascular deaths and 14 admissions per 100 middle-aged men and women over the next 20 years. CONCLUSION: Obesity is associated with an increase in a broad range of fatal and non-fatal cardiovascular events. Consideration of only coronary, only fatal, and only first events greatly underestimates the cardiovascular consequences of obesity.

Body Mass Index↗
PubMed2005

Carboxyhaemoglobin concentration, smoking habit, and mortality in 25 years in the Renfrew/Paisley prospective cohort study.

OBJECTIVE: To investigate how carboxyhaemoglobin concentration is related to smoking habit and to assess whether carboxyhaemoglobin concentration is related to mortality. DESIGN: Prospective cohort study. SETTING: Residents of the towns of Renfrew and Paisley in Scotland. PARTICIPANTS: The whole Renfrew/Paisley study, conducted between 1972 and 1976, consisted of 7048 men and 8354 women aged 45-64 years. This study was based on 3372 men and 4192 women who were screened after the measurement of carboxyhaemoglobin concentration was introduced about halfway through the study. MAIN OUTCOME MEASURES: Deaths from coronary heart disease (CHD), stroke, chronic obstructive pulmonary disease (COPD), lung cancer, and all causes in 25 years after screening. RESULTS: Carboxyhaemoglobin concentration was related to self reported smoking and for each smoking category was higher in participants who reported inhaling than in those who reported not inhaling. Carboxyhaemoglobin concentration was positively related to all causes of mortality analysed (relative rates associated with a 1 SD (2.93) increase in carboxyhaemoglobin for all causes, CHD, stroke, COPD, and lung cancer were 1.26 (95% confidence interval (CI) 1.19 to 1.34), 1.19 (95% CI 1.13 to 1.26), 1.19 (95% CI 1.13 to 1.26), 1.64 (95% CI 1.47 to 1.84), and 1.69 (95% CI 1.60 to 1.79), respectively). Adjustment for self reported cigarette smoking attenuated the associations but they remained relatively strong. CONCLUSIONS: Self reported smoking data were validated by the objective measure of carboxyhaemoglobin concentration. Since carboxyhaemoglobin concentration remained associated with mortality after adjustment for smoking, carboxyhaemoglobin seems to capture more of the risk associated with smoking tobacco than does self reported tobacco consumption alone. Analysing mortality by self reported cigarette smoking underestimates the strength of association between smoking and mortality.

Carboxyhemoglobin↗
PubMed2005

Childhood IQ of parents related to characteristics of their offspring: linking the Scottish Mental Survey 1932 to the Midspan Family Study.

The objective of the study was to investigate the relationship between childhood IQ of parents and characteristics of their adult offspring. It was a prospective family cohort study linked to a mental ability survey of the parents and set in Renfrew and Paisley in Scotland. Participants were 1921-born men and women who took part in the Scottish Mental Survey in 1932 and the Renfrew/Paisley study in the 1970s, and whose offspring took part in the Midspan Family study in 1996. There were 286 offspring from 179 families. Parental IQ was related to some, but not all characteristics of offspring. Greater parental IQ was associated with taller offspring. Parental IQ was inversely related to number of cigarettes smoked by offspring. Higher parental IQ was associated with better education, offspring social class and offspring deprivation category. There were no significant relationships between parental IQ and offspring systolic blood pressure, diastolic blood pressure, cholesterol, glucose, lung function, weight, body mass index, waist hip ratio, housing, alcohol consumption, marital status, car use and exercise. Structural equation modelling showed parental IQ associated with offspring education directly and mediated via parental social class. Offspring education was associated with offspring smoking and social class. The smoking finding may have implications for targeting of health education.

Adult↗
PubMed2005

Psychological distress, physical illness, and risk of coronary heart disease.

STUDY OBJECTIVE: The aims of this study are to confirm the association between psychological distress and coronary heart disease (CHD) using an epidemiological community study with hospital admissions data and to examine if any association is explained by existing illness. DESIGN: Prospective cohort study modelling the association between psychological distress, measured using the 30 item general health questionnaire (GHQ), and hospital admissions data for CHD (ICD 410-414), using proportional hazards modelling adjusted for sociodemographic, CHD risk factors, and angina, bronchitis, diabetes, ischaemia, and stroke. SETTING: Two suburbs of Glasgow, Renfrew and Paisley, in Scotland. PARTICIPANTS: 6575 men and women aged 45-64 years from Paisley. MAIN RESULTS: Five year CHD risk in distressed men compared with non-distressed men was 1.78 (95% confidence intervals (CI), 1.15 to 2.75) in age adjusted analysis, 1.78 (95% CI, 1.14 to 2.79) with sociodemographic and CHD risk factor adjustment, and 1.61 (95% CI 1.02 to 2.55) with additional adjustment for existing illness. Psychological distress was unrelated to five year CHD risk in women. In further analysis, compared with healthy, non-distressed men, distressed physically ill men had a greater risk of CHD than non-distressed physically ill men, a relative risk of 4.01 (95% CI 2.42 to 6.66) compared with 2.12 (95% CI 1.35 to 3.32). CONCLUSION: The association of psychological distress with an increased risk of five year CHD risk in men could be a function of baseline physical illness but an effect independent of physical illness cannot be ruled out. Its presence among physically ill men greatly increases CHD risk.

Coronary Disease↗
PubMed2005

Childhood IQ and all-cause mortality before and after age 65: prospective observational study linking the Scottish Mental Survey 1932 and the Midspan studies.

OBJECTIVES: The objective was to investigate how childhood IQ related to all-cause mortality before and after age 65. DESIGN: The Midspan prospective cohort studies, followed-up for mortality for 25 years, were linked to individuals' childhood IQ from the Scottish Mental Survey 1932. METHODS: The Midspan studies collected data on risk factors for cardiorespiratory disease from a questionnaire and at a screening examination, and were conducted on adults in Scotland in the 1970s. An age 11 IQ from the Scottish Mental Survey 1932, a cognitive ability test conducted on 1921-born children attending schools in Scotland, was found for 938 Midspan participants. The relationship between childhood IQ and mortality risk, adjusting for adulthood socio-economic confounders, was analysed. The effect of adjustment for childhood IQ on the relationship between established risk factors (blood pressure, smoking, height and respiratory function) and mortality was also investigated. RESULTS: For deaths occurring up to age 65, there was a 36% increased risk per standard deviation decrease (15 points) in childhood IQ which was reduced to 29% after adjusting for social class and deprivation category. There was no statistically significant relationship between childhood IQ and deaths occurring after the age of 65. Adjustment for childhood IQ attenuated the risk factor-mortality relationship in deaths occurring up to age 65, but had no effect in deaths occurring after age 65. CONCLUSIONS: Childhood IQ was significantly related to deaths occurring up to age 65, but not to deaths occurring after age 65.

Adolescent↗
PubMed2004

Childhood IQ and cardiovascular disease in adulthood: prospective observational study linking the Scottish Mental Survey 1932 and the Midspan studies.

This study investigated the influence of childhood IQ on the relationships between risk factors and cardiovascular disease (CVD), coronary heart disease (CHD) and stroke in adulthood. Participants were from the Midspan prospective cohort studies which were conducted on adults in Scotland in the 1970s. Data on risk factors were collected from a questionnaire and at a screening examination, and participants were followed up for 25 years for hospital admissions and mortality. 938 Midspan participants were successfully matched with their age 11 IQ from the Scottish Mental Survey 1932, in which 1921-born children attending schools in Scotland took a cognitive ability test. Childhood IQ was negatively correlated with diastolic and systolic blood pressure, and positively correlated with height and respiratory function in adulthood. For each of CVD, CHD and stroke, defined as either a hospital admission or death, there was an increased relative rate per standard deviation decrease (15 points) in childhood IQ of 1.11 (95% confidence interval 1.01-1.23), 1.16 (1.03-1.32) and 1.10 (0.88-1.36), respectively. With events divided into those first occurring before and those first occurring after the age of 65, the relationships between childhood IQ and CVD, CHD and stroke were only seen before age 65 and not after age 65. Blood pressure, height, respiratory function and smoking were associated with CVD events. Relationships were stronger in the early compared to the later period for smoking and FEV1, and stronger in the later compared to the earlier period for blood pressure. Adjustment for childhood IQ had small attenuating effects on the risk factor-CVD relationship before age 65 and no effects after age 65. Adjustment for risk factors attenuated the childhood IQ-CVD relationship by a small amount before age 65. Childhood IQ was associated with CVD risk factors and events and can be considered an important new risk factor.

Adolescent↗
PubMed2003

The Scottish mental survey 1932 linked to the Midspan studies: a prospective investigation of childhood intelligence and future health.

The Scottish mental survey of 1932 (SMS1932) recorded mental ability test scores for nearly all children born in 1921 and at school in Scotland on 1 June 1932. The Collaborative and Renfrew/Paisley studies, two of the Midspan studies, obtained health and social data by questionnaire and a physical examination in the 1970s. Some Midspan participants were born in 1921 and may also have taken part in the SMS1932, so there was a possibility that their mental ability data from childhood would be available. The 1921 born Midspan participants were matched with the computerized SMS1932 database, and in total, 1032 of 1251 people (82.5%) were matched successfully. Of those matched, 938 (90.9%) had a mental ability test score recorded. The mean score of the matched sample was 37.2 (standard deviation (SD) 13.9) out of a possible score of 76. The mean (SD) for the boys and girls was 38.3 (14.2) and 35.7 (13.9), respectively. This compared with 38.6 (15.7) and 37.2 (14.3) for boys and girls in all of Scotland. Graded relationships were found between mental ability in childhood, and social class and deprivation category of residence in adulthood. Being in a higher social class or in a more affluent deprivation category was associated with higher childhood mental ability scores, and the scores reduced with increasing deprivation. Future plans for the matched data include examining associations between childhood mental ability and other childhood and adult risk factors for disease in adulthood, and modelling childhood mental ability, alongside other factors available in the Midspan database, as a risk factor for specific illnesses, admission to hospital and mortality.

Adult↗
PubMed2003

Relation between number of siblings and adult mortality and stroke risk: 25 year follow up of men in the Collaborative study.

STUDY OBJECTIVE: To investigate the relation between number of siblings, mortality risk, and stroke risk. DESIGN: Prospective cohort study. SETTING: 27 workplaces in Scotland. PARTICIPANTS: 5765 employed men aged 35-64 from a variety of different workplaces, screened between 1970 and 1973. MAIN RESULTS: There were strong relationships between number of siblings and socioeconomic variables and also with adult behavioural measures. Men with greater numbers of siblings had an increased risk of dying of all causes, coronary heart disease, lung cancer, stomach cancer, and respiratory disease over a 25 year follow up period. Adjustment for risk factors could explain these associations, excepting stomach cancer mortality. With the definition of stroke as either a hospital admission for stroke or death from stroke, there was a strong relation between number of siblings and haemorrhagic stroke, but not ischaemic stroke. CONCLUSIONS: Number of siblings is strongly related to mortality risk, but as it is also related to many risk factors, adjustment for these can generally explain the relation with mortality. The exceptions are stomach cancer mortality and haemorrhagic stroke, which are known to be related to deprivation in childhood, and, in the case of stomach cancer to childhood infection.

Adult↗
PubMed2002

Gender differences in self-reported minor mental disorder and its association with suicide. A 20-year follow-up of the Renfrew and Paisley cohort.

BACKGROUND: Suicide rates are around three times higher in men than women; in contrast women have a higher prevalence of community-diagnosed depression. To investigate this paradox we examined the association of General Health Questionnaire (GHQ)-caseness (score > or = 4), a measure of possible minor mental disorder, with suicide risk in a general population cohort. METHODS: Data were derived from a cohort study based on the 8,466 men and women in the Renfrew and Paisley cohort who completed a 30-item GHQ in the period from 1972 to 1976 and who were followed up to 1995 for all-cause and suicide mortality. RESULTS: The long-term suicide risk associated with possible minor mental disorder was higher in men [hazard ratio 6.78 (1.36-33.71)] than women [hazard ratio 1.66 (0.43-6.45)]; test for interaction between gender and GHQ with respect to suicide risk: p = 0.09. CONCLUSION: These findings indicate either that the long-term risk of suicide in the context of a past episode of minor mental disorder is higher in males than females or that there are sex differences in the validity of responses to mental health screening questionnaires. Further research is required to replicate our finding in larger studies and, if confirmed, clarify which explanation underlies it.

Adolescent↗
PubMed2002

Common mental disorder and physical illness in the Renfrew and Paisley (MIDSPAN) study.

OBJECTIVE AND METHODS: The relationship between psychological distress measured by the General Health Questionnaire 30 (GHQ-30) and risk factors for coronary heart disease, angina, electrocardiogram (ECG) abnormalities and chronic sputum was modelled using logistic regression on baseline data from a community study of 15,406 men and women. RESULTS: Psychological distress was associated with low forced expiratory volume (FEV(1)) and low body mass index (BMI) in men, and low systolic blood pressure only in women. There were associations between psychological distress and coronary heart disease and cardiorespiratory outcomes. The associations were particularly strong for angina without ECG abnormalities (Men: OR 3.26, 95% CI 2.52-4.21; Women: OR 2.89, 95% CI 2.35-3.55) and for angina with ECG abnormalities (Men: OR 2.68, 95% CI 2.03-4.52; Women: OR 2.88, 95% CI 1.89-4.39), in both men and women, even after adjusting for classical CHD and cardiorespiratory risk factors. An association between psychological distress and severe chest pain, indicative of previous myocardial infarction, was found in both men and women (Men: OR 1.89, 95% CI 1.44-2.47; Women: OR 1.91, 95% CI 1.48-2.47), respectively, and between psychological distress and ECG ischaemia, but in men only (OR 1.32, 95% CI 1.00-1.76). CONCLUSION: The association between psychological distress and cardiorespiratory outcomes is likely to be a consequence of the pain and discomfort of the symptoms of the illness. Chest pain may also be a symptom of psychological distress. However, psychological distress, as a predictor and possible risk factor increasing the risk of coronary heart disease, cannot be ruled out.

Angina Pectoris↗
PubMed2001

Bupropion SR worsens mood during marijuana withdrawal in humans.

RATIONALE: Symptoms of withdrawal after daily marijuana smoking include increased ratings of irritability and depression. Similar mood symptoms are reported by cigarette smokers during nicotine abstinence. OBJECTIVE: Given the successful use of sustained-release bupropion in treating nicotine dependence, this study investigated how maintenance on bupropion influenced symptoms of marijuana withdrawal compared to maintenance on placebo. METHODS: Marijuana smokers (n=10) were maintained outpatient on active (300 mg/day) or placebo (0 mg/day) bupropion for 11 days, and were then maintained inpatient on the same bupropion dose for 17 days. For the first 4 inpatient days, participants smoked active marijuana [2.8% delta9-tetrahydrocannabinol (THC)] 5 times/day. For the remaining inpatient days, participants smoked placebo marijuana (0.0% THC) 5 times/day. Participants were then maintained outpatient on the alternate dose of bupropion for 11 days, followed by a second inpatient residential stay, paralleling the first. Medication administration was double-blind. Mood, psychomotor task performance, food intake, and sleep were measured daily during each inpatient phase. The order of active and placebo bupropion maintenance was counterbalanced between groups. RESULTS: Bupropion had few behavioral effects when participants smoked active marijuana. During placebo marijuana smoking, i.e., active marijuana withdrawal, ratings of irritability, restlessness, depression, and trouble sleeping were increased by bupropion compared to placebo maintenance. CONCLUSIONS: These data suggest that bupropion does not show promise as a potential treatment medication for marijuana dependence.

Adult↗
PubMed2001

Effects of repeated oral methamphetamine administration in humans.

RATIONALE: Although methamphetamine use has increased over the past several years, few studies have evaluated the effects of repeated methamphetamine administration in humans. OBJECTIVES: Because methamphetamine is often taken in a pattern of repeated use followed by a period of abstinence, the present study sought to evaluate the effects of repeated methamphetamine administration in humans. The hypothesis was that tolerance would develop to methamphetamine's effects. METHODS: Seven normal, healthy volunteers participated in a 15-day residential study. Participants completed subjective-effects questionnaires and psychomotor performance tasks repeatedly throughout the experimental day. Oral methamphetamine (5, 10 mg BID) was administered on days 4-6 and 10-12; placebo was administered on all other study days. RESULTS: Relative to placebo baseline, only two "positive" subjective ratings ("I feel a good drug effect" and "I feel high") were significantly elevated, and only on the 1st day of methamphetamine administration. In contrast, numerous "negative" ratings, including "I feel..." "a bad drug effect," "dizzy," and "flu-like symptoms" were elevated on the 3rd day of methamphetamine administration. Total caloric intake decreased and sleep was disrupted after methamphetamine administration, relative to baseline. CONCLUSIONS: The pattern of methamphetamine's positive subjective effects were altered with chronic administration such that tolerance, or a decreased effect, occurred after repeated administration. In contrast, methamphetamine's negative subjective effects increased over days. These results suggest that in this population of normal volunteers, the abuse liability of oral methamphetamine is relatively low.

Adult↗
PubMed2001

Methamphetamine self-administration by humans.

RATIONALE: Methamphetamine abuse has become increasingly problematic. Yet, the reinforcing effects of methamphetamine in humans have not been systematically evaluated. OBJECTIVE: To characterize methamphetamine's reinforcing effects in human research participants under controlled laboratory conditions. METHODS: Eight healthy research volunteers (one female, seven males) completed this 20-day residential study. On days 1, 5, 9, 13 and 17, at 1000 hours, participants received the "sample" oral dose of methamphetamine (0, 5, 10 mg) that was available for the next 3 days and they also received an alternative reinforcer, a $1 voucher (redeemable for cash at study's end). Over a 3-day period, volunteers participated in an eight-trial choice procedure, during which they had the opportunity to self-administer the dose of methamphetamine they most recently sampled or to receive the $1 voucher. RESULTS: Participants' choice to self-administer methamphetamine significantly increased when active methamphetamine (5 mg and 10 mg) was available compared to placebo. No difference of choice was noted between low-dose and high-dose methamphetamine. However, the sampled 10 mg methamphetamine dose significantly increased several "positive" subjective ratings including "High," "Good Drug Effect," and "Stimulated," whereas the sampled 5 mg methamphetamine dose did not. Both active methamphetamine doses caused significant reductions in daily total caloric intake, relative to the respective placebo conditions. CONCLUSION: These data demonstrate that oral methamphetamine is a positive reinforcer in humans.

Adult↗