Background. Previous twin studies of hyperactivity have supported a ‘contrast effect’, whereby the more hyperactive the rating of one twin, the less the rating of the other. It has not been clear whether contrast effects occur in the twins' behaviour or in the ratings made of their behaviour but the implications for hyperactivity are different under the two models.

Method. We use hyperactivity ratings from mothers and teachers for 1644 twin pairs in the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) to explore the origin of contrast effects, making use of independent teacher reports in a proportion of twins. Models were fitted separately for the two informants and jointly to ratings combined through a latent variable, using structural equation modelling.

Results. Models for maternal data confirm the contrast effect previously reported. Teacher ratings show a different form of bias, with both twin confusion and correlated errors representing alternative but not mutually exclusive explanations of the data. Latent variable modelling of the joint responses allowed comparison of a model in which the contrast effect was placed on maternal ratings, representing bias, versus one in which the contrast occurred in the underlying ‘true’ phenotype. The fit of the former model was significantly better.

Conclusions. Support is provided for the notion of contrast effects as a form of rater bias in maternal hyperactivity ratings. Different bias in teacher reports highlight that no one report can be considered a gold standard. The extent to which such biases may distort information for other data sources such as sib-pair studies of concordance/discordance is discussed.

Background. To test the hypothesis that the prevalence, in the general population, of symptoms of depression and anxiety declines with age.

Methods. A general population sample of 2725 persons aged 18 to 79 years was administered two inventories for current symptoms of depression and anxiety, together with measures of neuroticism and of exposures that may confer increased risk of such symptoms.

Results. Symptoms of depression showed a decline with age in both men and women. For anxiety, the decline was statistically significant for women but not consistently so for men. For the risk factors examined, there was a decline with age in the neuroticism score, the frequency of adverse life events, being seriously short of money and having had parents who separated or divorced. Further analysis showed that the association between age and a declining symptom score cannot be entirely attributed to these risk factors, with the single exception of neuroticism. The latter is itself likely to be contaminated by current symptoms.

Conclusion. Unless these findings are due to bias in the sample of those who agreed to participate, they add to the evidence that symptoms of depression and to a lesser extent of anxiety decline in prevalence with age. Some risk factors also decline with age. It now has to be determined if these cross-sectional observations are also to be found in longitudinal data; and what process may underlie this striking change in mental health during adulthood.

Background. Depressed patients show deficits on neuropsychological tests. However, the basis of these impairments and their relationship with mood disturbance remains unclear.

Methods. This paper reviews the literature regarding the relationship between mood disturbance and neuropsychological impairment in depression and the evidence for serotonergic and hypothalamic–pituitary–adrenal (HPA) axis involvement in these two domains.

Results. Mood disturbance and neuropsychological impairment both occur in depression, but have no clear relationship in time or degree. Impairment of post-synaptic 5-HT1A receptor function may result in the symptom of low mood in depression. Depressed patients demonstrate abnormalities in the functional control of the HPA axis with a resultant hypercortisolaemia, which may impair neuropsychological function. These processes may be related given the extensive interactions between the serotonergic system and the HPA axis.

Conclusions. We argue that there is a neurobiological cause of impaired neuropsychological function in depression. The complex relationship between neuropsychological function and mood may be a result of interactions between the serotonergic system and the HPA axis, particularly in the hippocampus with involvement of serotonergic 5-HT1A and glucocorticoid receptors. A primary dysfunction in these receptors will produce a lowering of mood and neuropsychological impairment respectively. Either dysfunction will result in a secondary impairment of the alternate system. Thus, the affective and psychological changes of depressive illness are likely to have complex relationships in time and severity to one another and the illness as a whole may result from a range of primary aetio-pathologies.

Background. Psychiatric history, familial history of suicide attempts, and certain traumatic life events are important predictors of suicidal thoughts and behaviour. We examined the epidemiology and genetics of suicidality (i.e. reporting persistent suicidal thoughts or a plan or suicide attempt) in a large community-based sample of MZ and DZ twin pairs.

Method. Diagnostic telephone interviews were conducted in 1992–3 with twins from an Australian twin panel first surveyed in 1980–82 (N=5995 respondents). Data were analysed using logistic regression models, taking into account twin pair zygosity and the history of suicidality in the respondent's co-twin.

Results. Lifetime prevalence of suicidal thoughts and attempts was remarkably constant across birth cohorts 1930–1964, and across gender. Major psychiatric correlates were history of major depression, panic disorder, social phobia in women, alcohol dependence and childhood conduct problems. Traumatic events involving assault (childhood sexual abuse, rape or physical assault) or status-loss (job loss, loss of property or home, divorce), and the personality trait neuroticism, were also significantly associated with suicide measures. Prevalence of serious suicide attempts varied as a function of religious affiliation. After controlling for these variables, however, history of suicide attempts or persistent thoughts in the respondent's co-twin remained a powerful predictor in MZ pairs (odds ratio=3·9), but was not consistently predictive in DZ pairs. Overall, genetic factors accounted for approximately 45% of the variance in suicidal thoughts and behaviour (95% confidence interval 33–51%).

Conclusions. Risk of persistent suicidal thoughts and suicide attempts is determined by a complex interplay of psychiatric history, neuroticism, traumatic life experiences, genetic vulnerability specific for suicidal behaviour and sociocultural risk or protective factors.

Background. Although high expressed emotion (EE) has been found to be an important predictor of poor prognosis in a wide range of conditions such as schizophrenia, anorexia and depression no complete explanation exists for individual differences in EE responses The aim of this paper is to investigate the role of intimacy in determining the level of EE in carers of people with dementia.

Methods. Ninety-nine carers of people with dementia who presented to Old Age Psychiatry Services in South and Central Manchester completed questionnaires to ascertain past and current levels of intimacy. Camberwell Family Interviews (CFIs) were carried out to ascertain levels of EE.

Results. Current intimacy was found to be strongly related to EE such that low current intimacy was associated with high EE and there was a significant difference between high and low intimacy groups on measures of criticism and hostility, though not warmth.

Conclusions. The association found between intimacy and EE indicates that high EE may be a characteristic of low intimacy relationships between the carer and the cared-for-person. Since the assessment of EE is time intensive, perhaps a measure of intimacy will provide a short-hand screen for identifying critical and hostile caring environments.

Background. Comparatively little is known about the long-term natural history of depressive disorders in the elderly living in the community. This is a follow-up of a subsample of the Continuing Health in the Community study random sample of the elderly population living in Liverpool.

Methods. The investigators followed up 120 cases of depression identified by a semi-structured interview schedule (GMS) for a period of 5 years. A similar number of other subjects defined as subcases of depression, other cases of mental illness and a random selection of non-cases were also included.

Results. The 5-year outcome for the cases of depression was worse than the outcome of the non-cases (relative mortality risk of 2·1, 95% confidence interval 1·1 to 3·9). Thirty-four per cent of the cases of depression died and 28% had dropped out during the follow-up. Of the 46 cases of depression who had a complete follow-up, 22% recovered from their symptoms, 30% were found to be AGECAT cases at one of the three follow-up waves, 24% were AGECAT cases at two of the three follow-up waves and the remaining 24% were AGECAT cases at each follow-up wave. Fifteen per cent of the surviving cases of depression were organic cases at the follow-up. Their anxiety co-morbid state and depression score were identified as predictors of poor outcome.

Conclusion. The findings of this study indicate that depressive disorders (most of which were untreated) found in the elderly community have a poor prognosis.

Background. Cortisol non-suppression following the dexamethasone suppression test (DST) has been found to a variable extent in schizophrenia. The aetiology is unclear but may be related to depression or negative symptoms.

Methods. The DST was administered to 64 patients with DSM-IV schizophrenia. All patients were screened for DSM-IV major depression and rated on the Hamilton Rating Scale for Depression (HRSD), Scale for Assessment of Negative Symptoms (SANS) and the Brief Psychiatric Rating Scale (BPRS).

Results. DSM-IV criteria for major depression was fulfilled by 36% of the patients and 42% of patients had a history of parasuicide. Four patients had undetectable levels of dexamethasone and were excluded from the endocrine analyses. Only one remaining patient had a cortisol level above the cut-off point (>138 nmol/l), indicating escape from dexamethasone suppression. The post-dexamethasone cortisol level correlated significantly with HRSD and BPRS scores but not with the SANS. The SANS and HRSD scores were not correlated, but they were independently correlated with the BPRS score.

Conclusions. In contrast to some other work, rates of dexamethasone non-suppression were very low; together with the high rates of depression, this suggests that depression in schizophrenia may have a different neuroendocrine profile from major depressive disorders. Failure to measure dexamethasone levels can be misleading.

Background. Very little is known about the pharmacokinetics of neuroleptic drugs in breast-feeding mothers and their infants or about possible adverse effects in the infants.

Method. Twelve mothers who breast-fed their infants were prescribed haloperidol, chlorpromazine or trifluoperazine. Two methods, enzyme immunoassay (EIA) and high performance liquid chromatography (HPLC) were used to assay these drugs in samples from mothers, but infants' samples were assayed only by the more sensitive EIA. Repeated clinical and developmental assessments of the breast-fed infants were carried out up to 30 months of age. The control subjects were 18 bottle-fed infants whose mothers were also prescribed neuroleptic or mood-stabilizing drugs.

Results. The total concentrations of neuroleptic drugs and their principal metabolites in maternal plasma were correlated with concentrations in fore-milk. Infants were ingesting up to 3% of the maternal daily dose per kg body weight and small amounts of the drugs were detected in infants' plasma and urine. Concentrations of haloperidol in the adult range were found in plasma from 2 of 5 infants assayed by EIA but there was no evidence of any acute or delayed adverse effects. Three other breast-fed infants whose mothers were prescribed both haloperidol and chlorpromazine showed a decline in their developmental scores from the first to the second assessment at 12–18 months.

Conclusion. More extensive longitudinal studies are needed but, in the meantime, there appears to be grounds for caution if breast-feeding mothers are prescribed doses of single or two neuroleptic drugs at the upper end of their recommended ranges.

Background. This two-stage prevalence survey involved geographically delimited areas, four urban (Liverpool, Newcastle, Nottingham and Oxford) and two rural (Cambridgeshire and Gwynedd), including institutions.

Methods. Stratified random population samples of people in their 65th year and above, from Family Health Service Authorities were studied. The sample was stratified (65–74 years and [ges ]75) to provide equal numbers. In Liverpool equal numbers in 5 year age groups were taken. After an initial screening interview, approximately 20% were selected on the basis of age, AGECAT organicity confidence level and MMSE score to proceed to a detailed assessment interview from which the full AGECAT organicity confidence level could be derived.

Results. Major influences on MMSE were confirmed as age, sex, social class and educational level. Estimates of prevalence of AGECAT O3 and above for each centre and the entire sample according to age are given, based on 1991 Census population structure, and suggest that around half a million (543400) people in England and Wales would be defined as case level by this method. The five centres employing the same methodology showed no heterogeneity in prevalence.

Conclusions. Prevalence of cognitive impairment and dementia appear not to vary widely across the centres examined in this study, which provides stable estimates by age and sex for AGECAT O3 and above, and norms for MMSE. Using these estimates as an indication of the size of the population affected, around 550000 individuals in England and Wales would be expected to be suffering from dementia of mild or greater severity.

Background. Prevalence rates of depression based on the GMS-AGECAT system are markedly higher than rates of major depression diagnosed using DSM-III and DSM-III-R criteria. Interpreting this finding is difficult since AGECAT diagnostic criteria have not been published.

Methods. We conducted a survey in Edmonton, Canada, in which 1119 community residents aged 65 years or older were administered the Geriatric Mental State (GMS) questionnaire. Depression was diagnosed using AGECAT and also according to criteria for DSM-IV major depression and minor depression. We identified 57 items in the GMS relating to major and minor depression which were then grouped into dysphoric, somatic and cognitive categories. The relationship of these symptoms to AGECAT depression was investigated by recoding symptoms to absent (nullifying) and recalculating the number of AGECAT cases. Data were weighted to reflect the underlying population.

Results. There were 143 cases of AGECAT depression (prevalence rate=11·4%), 14 cases of major depression (prevalence rate=0·86%) and 44 cases of minor depression (prevalence rate=3·6%). Of the 154 subjects with either AGECAT or DSM-IV depression, only 47 (31%) were depressed according to both diagnostic systems. Nullifying all dysphoric symptoms reduced the number of AGECAT cases to eight, whereas nullifying somatic and cognitive symptoms reduced the numbers of cases only to 138 and 142, respectively. By themselves, dysphoric symptoms accounted for 77 of the 143 cases of AGECAT depression, while somatic and cognitive symptoms alone accounted for no cases.

Conclusions. AGECAT depression is more inclusive than DSM-IV major or minor depression and AGECAT case status is determined mainly by the proportion of dysphoric symptoms.

Background. The social rank theory of psychopathology suggests that with the evolution of social hierarchies various psychobiological mechanisms became attuned to the success or failure in conflict situations. Specifically, subordinates and those who have lost status are at greater risk of pathology than winners and those of higher status. In this theory concepts of defeat and entrapment are seen to be of special relevance to the study of depression. We outline the role of defeat and entrapment within the social rank theory of depression.

Methods. New self-report measures of entrapment and defeat were developed and used to test predictions of the social rank theory of depression. Both a sample of students and depressed patients were assessed with these new scales and other social rank measures (e.g. social comparison and submissive behaviour).

Results. The entrapment and defeat measures were found to have good psychometric properties and significantly correlated with depression. They were also strongly associated with other rank variables. Defeat maintained a strong association with depression even after controlling for hopelessness (r=0·62), whereas the relationship between hopelessness and depression was substantially reduced when controlling for defeat. Entrapment and defeat added substantially to the explained variance of depression after controlling for the other social rank variables.

Conclusions. Defeat and entrapment appear to be promising variables for the study of depression. These variables may also help to develop linkages between human and animal models of psychopathology.

Background. Women with anorexia nervosa have a reduced fertility but they may have borne children before the onset of their illness or after partial recovery. Little is known on how to identify the anorexic mothers who underfeed their children and how to manage them. This article aims to remedy these gaps.

Methods. The clinical scientific method is the only means of identifying the children of anorexic mothers who are at risk. Eight such mothers were identified as a result of obtaining serial measurements of the children's weights and heights over time. Tanner–Whitehouse charts were used to plot weight for age and height for age. A simple rating scale was devised to measure the acceptance of treatment involving both mother and child.

Results. Nine children (eight boys and one girl) were found to have suffered food deprivation: with severe reduction in weight-for-age in six and in height-for-age in eight. Five siblings were not affected. Catch-up growth was correlated with the degree of engagement in treatment of both mother and child. Long-term treatment of one mother, combining family therapy with admissions to hospital, resulted in catch-up growth in her two sons.

Conclusions. The mechanisms underlying the privation of the children stem from the anorexic mother's abnormal concerns with body size extending to her children. The children may become unduly accepting of the underfeeding. It is essential to obtain the confidence of anorexic mothers suspected of underfeeding their children and to adopt a whole family approach to treatment.

Background. In unselected samples, the diagnosis of major depression (MD) is not highly reliable. It is not known if occasion-specific influences on reliability index familial risk factors for MD, or how reliability is associated with risk for co-morbid anxiety disorders.

Methods. An unselected sample of 847 female twin pairs was interviewed twice, 5 years apart, about their lifetime history (LTH) of MD, generalized anxiety disorder (GAD) and panic disorder (PD). Familial influences on reliability were examined using structural equation models. Logistic regression was used to identify clinical features that predict reliable diagnosis. Co-morbidity was characterized using the continuation ratio test.

Results. The reliability of a LTH of MD over 5 years was fair (κ=0·43). There was no evidence for occasion-specific familial influences on reliability, and heritability of reliably diagnosed MD was estimated at 66%. Subjects with unreliably diagnosed MD reported fewer symptoms and, if diagnosed with MD only at the first interview, less impairment and help seeking, or, if diagnosed with MD only at the second interview, fewer episodes and a longer illness. A history of co-morbid GAD or PD is more prevalent among subjects with reliably diagnosed MD.

Conclusions. A diagnosis of MD based on a single psychiatric interview incorporates a substantial amount of measurement error but there is no evidence that transient influences on recall and diagnosis index familial risk for MD. Quantitative indices of risk for MD based on multiple interviews should reflect both the characteristics of MD and the temporal order of positive diagnoses.

Background. Abnormal performance on the antisaccade task suggests that patients with schizophrenia have difficulty with the inhibition of reflexive attentional shifts. The aim of the study was to investigate whether deficits in the inhibition of reflexive attentional shifts were specific to the oculomotor modality or whether they could also occur when attentional shifts were made without eye movements (e.g. covert attentional shifts).

Methods. Fifteen medicated patients with chronic schizophrenia and 15 matched controls performed the antisaccade task and the covert orientating task (COVAT) where the probability of targets appearing at the same location of a peripheral cue was varied so that voluntary and reflexive orientating systems had the same goal (80% probability of target and cued condition) or opposite goals (20%probability of target at cued location). A condition where only reflexive orientating was initiated was also included (50% probability of target at cued location). For each of these conditions the stimulus onset asynchrony (SOA) varied between 150 and 350 ms.

Results. Patients with schizophrenia showed normal latency and accuracy for visually guided saccades but increased error rates and latency on the antisaccade task. For the COVAT, patients with schizophrenia were unable to use voluntary orientating strategies to inhibit reflexive shifts of covert attention. On conditions where only reflexive orientating was required or when the goals of the reflexive and voluntary orientating systems were the same, patients with schizophrenia showed normal performance.

Conclusions. These results suggest the reflexive orientating mode is normal in patients with chronic schizophrenia. However, these patients have a reduced ability to utilize the voluntary orientating mode to control or inhibit reflexive orientating. This impairment of voluntary control is evident for both overt and covert attentional shifts.

Background. Population-based studies suggest substantial co-morbidity between physical illness and depression in late-life. However, a causal relationship has not been established. If a relationship exists, it is important to establish which aspects of poor health determine risk for depression, and which factors confer vulnerability or resilience in the face of poor health. We investigate the role of disablement, measured as impairment, disability and handicap.

Methods. A prospective population-based cohort study, comprising an index assessment and 1 year follow-up, of all residents aged 65 years or over, of an electoral ward in London, UK (N=889).

Results. The prevalence of SHORT-CARE pervasive depression was 17·7% at index assessment. The 1 year onset rate for pervasive depression was 12·0%, and the 1 year maintenance rate 63·2%. There was a high mortality rate among the depressed. Disablement, particularly handicap was the most important predictor of the onset of depression (population attributable fraction, 0·69). Lack of contact with friends was a direct risk factor but also modified the association between handicap and depression. Marriage was protective for men, but a risk factor for women. Maintenance of depression was predicted by low levels of social support and social participation, rather than by disablement.

Conclusions. It seems likely that disablement, specifically handicap, is the chief cause of onsets of depression in late-life. Genetic predisposition, early adversity and serious life events may play a less prominent role than in earlier life. Effective prevention of late-life depression requires attention at the structural level to the sources of handicap within communities.

Background. A neuropsychological formulation of schizophrenia has suggested that problems with meta-representation underpin both positive and negative symptoms. This study tested Frith's account by asking patients experiencing an acute episode of psychosis to complete a set of tasks that involved Theory of Mind (ToM) skills.

Methods. Fourteen patients who fulfilled criteria for schizophrenia, 10 deluded patients who were suffering from psychotic disorders other than schizophrenia and 12 depressed patients completed second-order false belief tasks, a test which involved substitution of a co-referential term in a linguistic description of an event, and metaphor and irony tasks. The battery of tests was completed during the acute phase and following recovery. Selection of these patient groups allowed comparisons to be made between schizophrenia patients and non-schizophrenia patients and between patients with and without persecutory delusions.

Results. Schizophrenia patients, who had a multiplicity of positive and negative symptoms, performed significantly worse than non-schizophrenia patients on some of the ToM tasks during an acute episode. Patients with delusions of persecution and reference did not perform significantly worse than non-deluded patients on ToM tasks. There was no significant difference between groups in performance on any of the tasks at recovery.

Conclusions. The results provide at best weak support for Frith's account and it remains unclear whether the ToM deficits demonstrated are genuine deficits or are a result of information-processing overload. However, it is clear that difficulties interpreting interpersonal contexts, as shown by some schizophrenia patients, are state rather than trait characteristics.

Background. We sought to determine whether there was empirical support for the diagnostic thresholds of DSM-IV bulimia nervosa (BN) and whether an empirically derived typology resembled the diagnostic categories of DSM-IV.

Methods. Detailed information about bulimic behaviours were assessed via personal interview in a population-based sample of 1897 Caucasian female twins. We assessed the lifetime prevalence of the component bulimic behaviours and DSM-IV and DSM-III-R BN. Latent class analysis of nine separate bulimic symptoms was used to develop an empirical typology of bulimic behaviour.

Results. Although the lifetime prevalences of bingeing (23·6%) and vomiting (4·8%) were relatively common, DSM-IV BN was distinctly uncommon (0·5%). The criterion that specified the frequency and duration of bingeing and vomiting was an important limiting condition. Analysis of alternative thresholds found little support for the DSM-IV thresholds requiring an average of twice per week for 3 months. Latent class analysis yielded an interpretable four class solution that had little overlap with the DSM-IV typology.

Conclusions. As in other studies of unselected samples of women, the lifetime presence of bulimic behaviours are relatively high. Our results suggest that the DSM-IV approach to categorizing bulimic behaviour inadequately captures the spectrum of lifetime bulimic behaviours in the general population.

Background. The objective of this study was to test a guided imagery therapy designed to enhance self-comforting in bulimia nervosa.

Methods. A randomized controlled trial compared 6 weeks of individual guided imagery therapy with a control group. Fifty participants who met DSM-III-R criteria for bulimia nervosa completed the study. Measures of eating disorder symptoms, psychological functioning and the experience of guided imagery therapy were administered.

Results. The guided imagery treatment had substantial effects on the reduction of bingeing and purging episodes; the imagery group had a mean reduction of binges of 74% and of vomiting of 73%. The imagery treatment also demonstrated improvement on measures of attitudes concerning eating, dieting and body weight in comparison to the control group. In addition, the guided imagery demonstrated improvement on psychological measures of aloneness and the ability for self-comforting.

Conclusions. Evidence from this study suggests that guided imagery was an effective treatment for bulimia nervosa, at least in the short-term.

Background. As part of a longitudinal study, prevalence findings of DSM-IV disorders are presented for a random sample of 3021 respondents aged 14 to 24, with response rate 71%.

Method. Assessment included various subtypes of disorders, subthreshold conditions and disorders that have only rarely been studied in other epidemiological surveys. The computer-assisted Munich-Composite International Diagnostic Interview (M-CIDI) was used to derive DSM-IV diagnoses.

Results. Substance disorders were the most frequent (lifetime 17·7%; 12-month 11·4%), with abuse being considerably more frequent than dependence. Other mental disorders had a lifetime prevalence of 27·5% (12-month, 17·5%) with depressive disorders (16·8%) being more frequent than anxiety disorders (14·4%). Eating disorders (3·0%) and threshold somatoform disorders (1·2%) were rare disorders. Subthreshold anxiety and somatoform disorders, however, were more frequent than threshold disorders. Prevalence of disorders was equally high for males and females, although specific disorder prevalence varied significantly by gender. The co-occurrence of disorders (co-morbidity) was substantial and was significantly related to greater reductions in work productivity and increased rates of professional helpseeking behaviour.

Conclusions. Findings underline that mental disorders in young adults are frequent and impairing, limiting work and education ability and social interaction. Given the fact that adolescents and young adults are in a key phase of socialization in terms of professional career and interpersonal relationships, our findings indicate a considerable risk potential for an accumulation of complicating factors and future chronicity. This paper is the first report of this ongoing longitudinal study about early developmental conditions of mental disorders.

Background. Urban birth is associated with later schizophrenia. This study examined whether this finding is diagnosis-specific and which individuals are most at risk.

Methods. All live births recorded between 1942 and 1978 in any of the 646 Dutch municipalities were followed-up through the National Psychiatric Case Register for first psychiatric admission for psychosis between 1970 and 1992 (N=42115).

Results. Urban birth was linearly associated with later schizophrenia (incidence rate ratio linear trend (IRR), 1·39; 95% confidence interval (95% CI), 1·36–1·42), affective psychosis (IRR, 1·18; 95% CI, 1·15–1·21) and other psychosis (IRR, 1·27; 95% CI, 1·24–1·30). Individuals born in the highest category of the three-level urban exposure were around twice as likely to develop schizophrenia. Associations were stronger for men and for individuals with early age of onset. The effect of urban birth was also stronger in the more recent birth cohorts.

Conclusions. There are quantitative differences between diagnostic categories in the strength of the association between urban birth and later psychiatric disorder. High rates of psychosis in urban areas may be the result of environmental factors associated with urbanization, the effect of which appears to be increasing over successive generations.