Influence of birth cohort on age of onset cluster analysis in bipolar I disorder

AbstractPurpose:Two common approaches to identify subgroups of patients with bipolar disorder are clustering methodology (mixture analysis) based on the age of onset, and a birth cohort analysis. This study investigates if a birth cohort effect will influence the results of clustering on the age of onset, using a large, international database.Methods:The database includes 4037 patients with a diagnosis of bipolar I disorder, previously collected at 36 collection sites in 23 countries. Generalized estimating equations (GEE) were used to adjust the data for country median age, and in some models, birth cohort. Model-based clustering (mixture analysis) was then performed on the age of onset data using the residuals. Clinical variables in subgroups were compared.Results:There was a strong birth cohort effect. Without adjusting for the birth cohort, three subgroups were found by clustering. After adjusting for the birth cohort or when considering only those born after 1959, two subgroups were found. With results of either two or three subgroups, the youngest subgroup was more likely to have a family history of mood disorders and a first episode with depressed polarity. However, without adjusting for birth cohort (three subgroups), family history and polarity of the first episode could not be distinguished between the middle and oldest subgroups.Conclusion:These results using international data confirm prior findings using single country data, that there are subgroups of bipolar I disorder based on the age of onset, and that there is a birth cohort effect. Including the birth cohort adjustment altered the number and characteristics of subgroups detected when clustering by age of onset. Further investigation is needed to determine if combining both approaches will identify subgroups that are more useful for research.

Download Full-text

Age–period–cohort analysis of the incidence of schizophrenia in Scotland

Psychological Medicine ◽

10.1017/s0033291700035297 ◽

1996 ◽

Vol 26 (5) ◽

pp. 963-973 ◽

Cited By ~ 27

Author(s):

Noriyoshi Takei ◽

Glyn Lewis ◽

Pak C. Sham ◽

Robin M. Murray

Keyword(s):

Birth Cohort ◽

Cohort Analysis ◽

Cohort Effect ◽

National Sample ◽

Period Effect ◽

Cross Sectional ◽

Admission Rates ◽

Schizophrenic Patients ◽

Birth Cohort Effect ◽

First Admission

SynopsisStudies examining a possible decline in the incidence of schizophrenia over the last two to three decades have paid little attention to the possible role of birth cohort effects. We collected data on a Scottish national sample of all schizophrenic patients, admitted for the first time between 1966 and 1990 (N = 11348; male = 6301). In an Age–Period–Cohort analysis, a full model, incorporating three factors, had a substantially better fit to the data than other models (especially, an Age–Period model), providing clear evidence of the presence of a cohort effect. After adjustment for the effects of age and period, there was a 55% reduction in the rate of schizophrenia in men and a 39% fall in the number of women over the 50-year birth period from 1923 to 1973. The marked decline in the first admission rates observed in Scotland cannot, however, be attributed entirely to this cohort effect. Rather, a greater proportion of the declining first admission rates (88%) is ascribed to the period effect (i.e. artefactual or causally related cross-sectional effects). Nevertheless, the fact that a birth-cohort effect accounts for part of the declining incidence, suggests that causal environmental factors operating early in life have been diminishing in intensity.

Download Full-text

Gastric Cancer Mortality Trends in Tuscany, Italy, 1971–2004

Tumori Journal ◽

10.1177/030089160809400602 ◽

2008 ◽

Vol 94 (6) ◽

pp. 787-792 ◽

Cited By ~ 2

Author(s):

Giuseppe Gorini ◽

Lucia Giovannetti ◽

Giovanna Masala ◽

Elisabetta Chellini ◽

Andrea Martini ◽

...

Keyword(s):

Gastric Cancer ◽

High Risk ◽

Birth Cohort ◽

Cancer Mortality ◽

Cohort Effect ◽

Low Risk ◽

Period Effect ◽

Mortality Trends ◽

Risk Areas ◽

Birth Cohort Effect

Aims, Background, and Methods In Tuscany, Italy, gastric cancer mortality has been decreasing since 1950, although with relevant geographical variability across the region. In Eastern Tuscan areas close to the mountains (high risk areas), gastric cancer mortality has been and is still significantly higher than that recorded in Western coastal areas and in the city of Florence (low risk areas). High-risk areas also showed higher Helicobacter pylori seroprevalence. Aim of this paper is to study gastric cancer mortality trends in high and low-risk areas, during the period 1971–2004, using age-period-cohort models. Results In high-risk areas, gastric cancer mortality rates declined from 61.4 per 100,000 in 1971–74 to 19.8 in 2000–2004 and in low-risk areas from 34.9 to 9.8. Mortality decline in high-risk areas was mainly attributable to a birth cohort effect, whereas in low-risk areas it was due either to a birth cohort effect or a period effect. In low- and high-risk areas, birth-cohort risks of dying decreased over subsequent generations, except for the birth cohorts born around the second world war. Conclusions Gastric cancer mortality in areas with higher H. pylori seroprevalence in Tuscany (high-risk areas) showed a predominant decline by birth cohort, in particular for younger generations, possibly due to the decrease of the infection for improvement of living conditions.

Download Full-text

The paradox of longer sperm telomeres in older men’s testes: a birth-cohort effect caused by transgenerational telomere erosion in the female germline

Molecular Cytogenetics ◽

10.1186/s13039-016-0224-1 ◽

2016 ◽

Vol 9 (1) ◽

Cited By ~ 13

Author(s):

Reinhard Stindl

Keyword(s):

Birth Cohort ◽

Cohort Effect ◽

Birth Cohort Effect ◽

Female Germline ◽

Telomere Erosion

Download Full-text

Is there a birth cohort effect for Crohn's disease?

Gastroenterology ◽

10.1016/s0016-5085(00)81307-4 ◽

2000 ◽

Vol 118 (4) ◽

pp. A1359

Author(s):

Danielle L. Morris ◽

David A. Leon ◽

James Kyle ◽

Scott M. Montgomery ◽

Roy E. Pounder ◽

...

Keyword(s):

Crohn’S Disease ◽

Crohn's Disease ◽

Birth Cohort ◽

Cohort Effect ◽

Birth Cohort Effect

Download Full-text

Trends in the prevalence of social phobia in the United States: a synthetic cohort analysis of changes over four decades

European Psychiatry ◽

10.1016/s0924-9338(00)00213-3 ◽

2000 ◽

Vol 15 (1) ◽

pp. 29-37 ◽

Cited By ~ 80

Author(s):

R.G. Heimberg ◽

M.B. Stein ◽

E. Hiripi ◽

R.C. Kessler

Keyword(s):

Social Phobia ◽

Latent Class ◽

Age Of Onset ◽

Cohort Analysis ◽

Cohort Effect ◽

Composite International Diagnostic Interview ◽

The United States ◽

Lifetime Prevalence ◽

Future Research ◽

Co Morbidity

SummaryPrevious analysis of data from the U.S. National Comorbidity Survey (NCS) suggested that the lifetime prevalence of social phobia in the community has increased significantly in recent cohorts. Furthermore, a latent class analysis of NCS data revealed two primary classes of persons with social phobia: those with exclusive speaking fears and those with one or more other social-evaluative fears. Social phobia in the other social fear group is more persistent, more impairing, and more highly co-morbid with other DSM-III-R disorders. The current report presents data on whether the cohort effect is a general aspect of social phobia or is specific to one of the NCS social phobia subtypes, and whether the cohort effect varies as a function of socio-demographic characteristics. Data were drawn from the NCS. Social phobia was assessed with a revised version of the Composite International Diagnostic Interview. Retrospective age of onset reports were used to estimate Kaplan-Meier survival curves for first onset of social phobia in each cohort represented in the survey. Comparison of these curves allowed us to make synthetic estimates based on retrospective reports of intercohort trends in lifetime prevalence. The lifetime prevalence of social phobia appears to have increased in recent cohorts. However, this increase does not exist among social phobics with exclusive fears of speaking. The increase is most pronounced among white, educated, and married persons, and it is not explained by increased co-morbidity with other mental disorders. The fact that the cohort effect is more pronounced for social phobia with one or more non-speaking fears is important in that this is generally a more severe form of the disorder with an earlier age of onset than social phobia with pure speaking fears. The fact that the cohort effect is most pronounced among people with social and economic advantage (i.e., white, married, well-educated) is intriguing and raises questions about the etiologic process that warrant further study in future research.

Download Full-text

Extension of Cox Proportional Hazard Model for Estimation of Interrelated Age-period-Cohort Effects on Cancer Survival

Cancer Informatics ◽

10.4137/cin.s6770 ◽

2011 ◽

Vol 10 ◽

pp. CIN.S6770 ◽

Cited By ~ 1

Author(s):

Tengiz Mdzinarishvili ◽

Michael X. Gleason ◽

Leo Kinarsky ◽

Simon Sherman

Keyword(s):

Birth Cohort ◽

Survival Data ◽

Hazard Function ◽

Cohort Effect ◽

Age At Diagnosis ◽

Cohort Effects ◽

Proportional Hazard ◽

Cox Proportional Hazard ◽

Time Period ◽

Birth Cohort Effect

In the frame of the Cox proportional hazard (PH) model, a novel two-step procedure for estimating age-period-cohort (APC) effects on the hazard function of death from cancer was developed. In the first step, the procedure estimates the influence of joint APC effects on the hazard function, using Cox PH regression procedures from a standard software package. In the second step, the coefficients for age at diagnosis, time period and birth cohort effects are estimated. To solve the identifiability problem that arises in estimating these coefficients, an assumption that neighboring birth cohorts almost equally affect the hazard function was utilized. Using an anchoring technique, simple procedures for obtaining estimates of interrelated age at diagnosis, time period and birth cohort effect coefficients were developed. As a proof-of-concept these procedures were used to analyze survival data, collected in the SEER database, on white men and women diagnosed with LC in 1975–1999 and the age at diagnosis, time period and birth cohort effect coefficients were estimated. The PH assumption was evaluated by a graphical approach using log-log plots. Analysis of trends of these coefficients suggests that the hazard of death from LC for a given time from cancer diagnosis: (i) decreases between 1975 and 1999; (ii) increases with increasing the age at diagnosis; and (iii) depends upon birth cohort effects. The proposed computing procedure can be used for estimating joint APC effects, as well as interrelated age at diagnosis, time period and birth cohort effects in survival analysis of different types of cancer.

Download Full-text

Improved Cognitive Function in the Tromsø Study in Norway From 2001 to 2016

Neurology Clinical Practice ◽

10.1212/cpj.0000000000001115 ◽

2021 ◽

pp. 10.1212/CPJ.0000000000001115

Author(s):

Bente Johnsen ◽

Bjørn Heine Strand ◽

Ieva Martinaityte ◽

Ellisiv B. Mathiesen ◽

Henrik Schirmer

Keyword(s):

Physical Activity ◽

Birth Cohort ◽

Age Groups ◽

Cohort Effect ◽

Cognitive Test ◽

Birth Cohorts ◽

Cohort Differences ◽

Level Increase ◽

Drinking Frequency ◽

Birth Cohort Effect

AbstractObjective:Physical capacity and cardiovascular risk profiles seem to be improving in the population. Cognition have been improving due to a birth cohort effect, but evidence is conflicting on whether this improvement remains in the latest decades, and what is causing the changes in our population over 60 years old. We aimed to investigate birth cohort differences in cognition.Method:The study comprised 9514 participants from the Tromsø study, an ongoing longitudinal cohort study. Participants were in the ages 60–87 years, born between 1914 and 1956. They did four cognitive tests in three waves during 2001-2016. Linear regression was applied, and adjusted for age, education, blood pressure, smoking, hypercholesterolemia, stroke, heart attack, depression, diabetes, physical activity, alcohol use, BMI and height.Results:Cognitive test scores were better in later-born birth cohorts for all age groups, and in both sexes, compared with earlier born cohorts. Increased education, physical activity, alcohol intake, decreasing smoking prevalence and increasing height was associated with one third of this improvement across birth cohorts in women and one half of the improvement in men.Conclusion:Cognitive results were better in more recent born birth cohorts compared with earlier born, assessed at the same age. The improvement was present in all cognitive domains, suggesting an overall improvement in cognitive performance. The 80-year-olds assessed in 2015-16 performed like 60-year-olds assessed in 2001. The improved scores were associated with increased education level, increase in modest drinking frequency, increased physical activity and for men, smoking cessation and increased height.

Download Full-text

Persistence of the Decline in the Diagnosis of Schizophrenia Among First Admissions to Scottish Hospitals from 1969 to 1988

The British Journal of Psychiatry ◽

10.1192/bjp.163.5.620 ◽

1993 ◽

Vol 163 (5) ◽

pp. 620-626 ◽

Cited By ~ 41

Author(s):

John R. Geddes ◽

Roger J. Black ◽

Lawrence J. Whalley ◽

John M. Eagles

Keyword(s):

Birth Cohort ◽

Age Groups ◽

Admission Rate ◽

Cohort Effect ◽

Affective Psychoses ◽

Admission Rates ◽

Younger Age ◽

Birth Cohort Effect ◽

First Admission

Age-standardised rates were calculated for first admissions to hospital in Scotland with ICD-9 diagnoses of schizophrenia, affective psychoses, paranoid psychoses, reactive psychoses and depressive neuroses (ICD-9 295, 296, 297, 298 and 300.4) for the period 1969–88. First-admission rates for schizophrenia declined by an average of 3.3% per year in males and 4.4% per year in females over the period. The first-admission rate in males in 1988 was 8.4/100 000 (57% of 1969 rate) and in females was 4.8/100 000 (43% of 1969 rate). Rates for depressive neuroses, affective psychoses, reactive psychoses and combined psychoses also fell. Rates for mania rose, as did those for paranoid states in males. The decrease in first-admission rates is likely to reflect a true decrease in the incidence of schizophrenia over the period. The decline was unlikely to be accounted for by diagnostic change because there was no reciprocal increase in any other diagnosis sufficient to account for the change, and the rates for combined psychoses also decreased. There was evidence that rates for schizophrenia declined to a greater extent in younger age groups, especially in females. This could imply the presence of a birth cohort effect.

Download Full-text