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Biomedical subjects

A D McNeill

Publications and source records attributed to A D McNeill.

At least 19 recordsLinked to original sources
PubMed2002

Development of symptoms of tobacco dependence in youths: 30 month follow up data from the DANDY study.

OBJECTIVE: To determine if there is a minimum duration, frequency or quantity of tobacco use required to develop symptoms of dependence. DESIGN AND SETTING: A retrospective/prospective longitudinal study of the natural history of tobacco dependence employing individual interviews conducted three times annually in two urban school systems over 30 months. Detailed histories of tobacco use were obtained including dates, duration, frequency, quantity, patterns of use, types of tobacco, and symptoms of dependence. PARTICIPANTS: A cohort of 679 seventh grade students (age 12-13 years). MAIN OUTCOME MEASURES: The report of any of 11 symptoms of dependence. RESULTS: Among 332 subjects who had used tobacco, 40% reported symptoms, with a median latency from the onset of monthly smoking of 21 days for girls and 183 days for boys. The median frequency of use at the onset of symptoms was two cigarettes, one day per week. The report of one or more symptoms predicted continued smoking through the end of follow up (odds ratio (OR) 44, 95% confidence interval (CI) 17 to 114, p < 0.001). CONCLUSIONS: Symptoms of tobacco dependence commonly develop rapidly after the onset of intermittent smoking, although individuals differ widely in this regard. Girls tend to develop symptoms faster. There does not appear to be a minimum nicotine dose or duration of use as a prerequisite for symptoms to appear. The development of a single symptom strongly predicted continued use, supporting the theory that the loss of autonomy over tobacco use begins with the first symptom of dependence.

Adolescent↗
PubMed2000

Initial symptoms of nicotine dependence in adolescents.

OBJECTIVES: It has been assumed that nicotine dependence has a slow onset and occurs only after prolonged daily use of tobacco. A cohort of young adolescents was followed to determine when the first symptoms of nicotine dependence occur with respect to the duration and frequency of tobacco use. DESIGN: A cohort of 681 seventh grade students (age 12-13 years) from seven schools in two small cities in central Massachusetts was followed over one year. Detailed information regarding tobacco use was obtained in individual confidential interviews conducted in school three times over the year. The latency time to the onset of symptoms of nicotine dependence was measured from the time a subject first smoked at a frequency of at least once per month. RESULTS: 22% of the 95 subjects who had initiated occasional smoking reported a symptom of nicotine dependence within four weeks of initiating monthly smoking. One or more symptoms were reported by 60 (63%) of these 95 subjects. Of the 60 symptomatic subjects, 62% had reported experiencing their first symptom before smoking daily or began smoking daily only upon experiencing their first symptom. DISCUSSION: The first symptoms of nicotine dependence can appear within days to weeks of the onset of occasional use, often before the onset of daily smoking. The existence of three groups of individuals-rapid onset, slower onset, and resistant-distinguishable from one another by their susceptibility to nicotine dependence, is postulated.

Adolescent↗
PubMed1992

Manual dilatation of the anus.

A group of 100 consecutive patients undergoing manual dilatation of the anus between 1980 and 1983 were reviewed retrospectively by examining the clinical presentation, diagnosis, treatment and outcome. Anal fissure was diagnosed in 46 patients, 22 had either first- or second-degree haemorrhoids, and stenosis of the anal canal was identified in seven. Manual dilatation of the anus was performed on 25 patients in the absence of a diagnosis. Dilatation failed to treat 26 anal fissures successfully. Where it was employed alone in ten cases of haemorrhoids and seven of anal stenosis, manual dilatation failed to cure seven and five patients respectively. Of the patients with no diagnosis, 23 were relieved of their symptoms following dilatation. Episodes of incontinence occurred in 27 patients, 21 of whom were female. There should be a reduced role for manual anal dilatation in the treatment of common anorectal disorders.

Adolescent↗
PubMed1991

Factors determining exposure to passive smoking in young adults living at home: quantitative analysis using saliva cotinine concentrations.

Saliva cotinine concentrations were used to examine determinants of exposure to environmental tobacco smoke in 393 non-smoking students (age range 16-19 years) attending a sixth form college and living at home. Average concentrations were low (median 0.60 ng/ml), reflecting partly the warm weather at the time of the survey and partly the predominantly middle class sample. Despite this, cotinine levels were strongly related to the extent of self-reported passive smoking in the past three days (medians 0.30, 0.60, 0.90 and 1.35 ng/ml in those reporting 'None at all', 'A little', 'Some' and 'A lot' respectively, p less than 0.0001). Individual sources of environmental tobacco smoke identified were smoking by mothers (p less than 0.0001), by fathers (p less than 0.01), and exposure at college (p less than 0.001) and when out in the evenings (p less than 0.001). The results indicate that exposure outside the home may become of equal or greater importance than family smoking in determining the overall passive smoking dose received by this age group.

Adolescent↗
PubMed1991

The development of dependence on smoking in children.

The development of dependence on smoking has been largely unexplored and has theoretical importance and implications for interventions aimed at interrupting the early stages of smoking behaviour. Data are presented which indicate the importance of the first few cigarettes. The development of a regular smoking pattern had previously been reported to take about 2 years and involve a progression through a series of stages from smoking for psychosocial motives, to smoking for a positive nicotine effect and finally for some smokers, smoking to avoid withdrawal. Results from a small scale study with girls are described which give no support to the notion of any such well-defined stages in the novice smoker's career. Inhalation was apparent from early on indicating that nicotine can play an active role in reinforcing smoking from a very early stage. Furthermore, the majority of the young smokers perceived themselves to be dependent on their cigarettes. The nature of any positive reinforcement was unclear, the dependence-producing potential of smoking appearing to be largely due to relief of unpleasant feelings. These findings need to be replicated and the paper highlights other key areas in this field for future research.

Adolescent↗
PubMed1990

Children's purchases of single cigarettes: evidence for drug pushing?

The purchase of single cigarettes from shops by children aged 14 and 15, to whom all cigarette sales are illegal, was studied in a survey of 3513 teenagers attending nine state secondary schools in the Bristol area. Of those children who had tried smoking only once, 5% reported having at some time purchased a single cigarette from a shop. This percentage rose to 18% in current occasional smokers of less than 1 cigarette per week, and reached 52% in those smoking more than 6 cigarettes per week. There was no difference by sex or age, but some evidence of an association with family smoking habits and with social class, and wide variation between schools. In the school with the highest incidence, 80% of regular daily smokers had at some time bought single cigarettes from a shop, compared with 14% in the school with the lowest. Only 1% of children who smoked said that buying single cigarettes from shops was their usual way of getting cigarettes. Our results imply a cynical flouting of the law by many shopkeepers who are acting straightforwardly as drug pushers.

Adolescent↗
PubMed1989

Prospective study of factors predicting uptake of smoking in adolescents.

Risk factors for the uptake of cigarette smoking were examined prospectively in 2159 non-smoking secondary schoolchildren aged 11-13 who participated in a survey in 1983 and were followed up 30 months later, by which time 35 per cent had taken up smoking. In a multivariate logistic model, the strongest predictors to emerge were prior experimentation with cigarettes and sex, with more girls (41%) than boys (30%) starting to smoke. Other predictors of taking up smoking were being uncertain about smoking in the future, reporting having been drunk, having a boy or girl friend, believing teachers and friends would not mind if they took up smoking, and giving lower estimates of prevalence of smoking among teachers. Parental smoking behaviour and attitudes, beliefs about the effects of smoking on health, opinions about smoking and perceived strictness of parents did not predict take up of smoking when other variables were controlled for. The odds of taking up smoking varied from 0.24 (risk = 0.19) for a child with the most favourable combination of risk factors to 3.49 (risk = 0.78) for a child with the worst prognosis. These results differ from those of many cross sectional studies and hence indicate the importance of a prospective approach to this type of research.

Adolescent↗
PubMed1989

Nicotine intake in young smokers: longitudinal study of saliva cotinine concentrations.

Smoking habits and smoke intake were studied over three consecutive years in 197 girls, initially aged 11 to 14 years. Saliva cotinine concentrations in girls who were smokers throughout the three years increased over each year of the study, the greatest increase occurring during movement from occasional to daily smoking. Cigarette consumption also increased over the two years. For a group of continuing daily smokers (n = 23), inhalation of smoke per cigarette as indexed by the ratio of cotinine concentration to average daily cigarette consumption did not change over time. Cotinine concentrations in 16 girls who were smoking on a daily basis within a year of starting to smoke suggested the early development of inhalation. Our findings suggest that young smokers learn to inhale cigarette smoke very early in their smoking careers, that further increases in smoke intake mainly reflect increased cigarette consumption, and that the pharmacological effects of nicotine are already important in reinforcing their smoking.

Adolescent↗
PubMed1987

Subjective effects of cigarette smoking in adolescents.

Eighty-two per cent of a sample of 170 female adolescent smokers reported experiencing one or more of five specified subjective effects of smoking. Feeling calmer was the most frequently reported effect and daily smokers were more likely to report this than non-daily smokers (64% versus 38%, P less than 0.001). Self-reports of cigarette consumption and depth of inhalation and measures of smoke intake (salivary cotinine and expired-air carbon monoxide levels) were positively related to the report of feeling calmer when smoking and negatively related to feeling dizzy/light-headed and sick when smoking. The likelihood of experiencing at least one withdrawal effect when trying to quit was greater amongst those who reported feeling calmer when smoking (82% versus 40%, P less than 0.001). These results indicate that subjective effects of smoking are commonly reported by children and it is possible that pharmacological factors are implicated alongside psychosocial ones even at this early stage.

Adolescent↗
PubMed1986

Cigarette withdrawal symptoms in adolescent smokers.

One hundred and sixteen female adolescent smokers were asked about withdrawal symptoms experienced during past attempts to give up smoking for good. Sixty-three percent reported difficulties during abstinence of the kind experienced by adult smokers. Daily smokers were more likely to report withdrawal effects than non-daily smokers (74% versus 47%, P less than 0.005). Reported experience of withdrawal symptoms was positively related to self-reports of cigarette consumption and depth of inhalation and nicotine intake as indexed by salivary cotinine concentrations. Reported occurrence of at least one withdrawal effect correlated positively with nicotine intake after controlling for behavioural variables. Our results indicate that teenage smokers are likely to suffer withdrawal symptoms when they try to give up. Behavioural factors and expectations based on observations of adults may have played a part in their experience of withdrawal, but it is also likely that pharmacological factors are implicated even at this early stage.

Adolescent↗
PubMed1986

Do older children take in more smoke from their cigarettes? Evidence from carbon monoxide levels.

Expired-air carbon monoxide (CO) concentrations were measured in 125 pupils aged 11-17 years attending a girls' comprehensive school in the South of England who had smoked at least one cigarette on the day of testing. Both number of cigarettes smoked on the day of testing and time since the last cigarette were independently related to CO concentrations. Although there was a positive correlation between age and CO, this disappeared when number of cigarettes smoked on the day of testing and time since the last cigarette were taken into account. Previous reports of increasing CO concentrations with age taking account of cigarette consumption may be due to the use of usual daily cigarette consumption rather than number on the day of testing, which is more relevant given the short half-life of CO in the blood. In this sample, no evidence was found for an increase in smoke inhalation with increasing age.

Adolescent↗