Subthreshold conditions (i. e. not meeting full diagnostic criteria for mental disorders in DSM–IV or ICD–10) are prevalent and associated with significant costs and disability. Observed more in primary care and community populations than in speciality settings, varying conceptualisations have been applied to define these conditions.

To examine definitional issues for subthreshold forms of depression (e. g. minor depression) and to suggest future directions for research and nosology in psychiatry and primary care.

A Medline search was conducted. The relevant articles were reviewed with regard to specific categories of information.

Studies applied a myriad of names and definitions for subthreshold depression with varying duration, symptom thresholds and exclusions. Prevalence rates also vary depending upon the definitions, settings and populations researched.

Future research needs to apply methodological and intellectual rigour and systematically consider a broader clinical and nosological context. In addition, collaboration between psychiatry and primary care on research and clinical issues is needed.

Antidepressant drugs are usually prescribed at low doses, possibly to avoid adverse reactions. No comprehensive review has addressed the issue of dose, clinical response and tolerability in a quantitative way.

To determine whether high doses of antidepressants are more effective than lowdoses, and how safety is affected by dose.

Trials comparing two or more doses of the same antidepressant were located, and all antidepressants administered were converted to the equivalent dose of imipramine. Generalised estimating equations were used to analyse percentage improvement and adverse event rate according to dose level.

Thirty-three studies were identified. The dose level 100-200 mg imipramine equivalents showed an average improvement of 53% by ‘intention-to-treat’. Higher doses were not accompanied by increased efficacy, while lower doses showed reduction in efficacy. Adverse events significantly increased with dose.

With a low dose of antidepressants, clinicians trade off a slightly reduced chance of improvement for a higher chance of avoiding adverse reactions.

The EURODEP collaboration was formed to take advantage of existing studies of random community samples of older people in Europe, using GMS–AGECAT for case identification and diagnosis. Later, other centres joined, and the EURO–D scale was developed to harmonise the different methods used with the GMS. Previous studies had revealed different levels of depression in Europe but had been confounded by the use of unreconcilable methods. These studies attempt to overcome this problem.

To introduce the first set of publications from the EURODEP collaboration.

Presented in five accompanying papers (pp. 307–345, this issue)

Despite considerable interest, there is no consensus regarding the prevalence of depression in later life.

To assess the prevalence of late-life depression in the community.

A systematic review of community-based studies of the prevalence of depression in later life (55+). Literature was analysed by level of caseness at which depression was defined and measured.

Thirty-four studies eligible for inclusion were found. The reported prevalence rates vary enormously (0.4–35%). Arranged according to level of caseness, major depression is relatively rare among the elderly (weighted average prevalence 1.8%), minor depression is more common (weighted average prevalence 9.8%), while all depressive syndromes deemed clinically relevant yield an average prevalence of 13.5%. There is consistent evidence for higher prevalence rates for women and among older people living under adverse socio-economic circumstances.

Depression is common in later life. Methodological differences between studies preclude firm conclusions about cross-cultural and geographical variation. Improving the comparability of epidemiological research constitutes an important step forward.

This is the first report of results from the EURODEP Programme.

To assess the prevalence of depression judged suitable for intervention in randomised samples of those aged ⩾65 in nine European centres.

The GMS-AGECAT package.

Differences in prevalence are apparent, 8.8% (Iceland) to 23.6% (Munich). When sub-cases and cases are added together, five high- and four low-scoring centres emerge. Women predominated over men. Proportions of sub-cases to cases revealed striking differences but did not explain prevalence. There was no constant association between prevalence and age. A meta-analysis (n=13 808) gave an overall prevalence of 12. 3%, 14.1% for women and 8.6% for men.

Considerable variation occurs in the levels of depression across Europe, the cause for which is not immediately obvious. Case and sub-case levels taken together show greater variability, suggesting that it is not a matter of case/sub-case selection criteria, which were standardised by computer. Substantial levels of depression are shown but 62–82% of persons had no depressive level. Opportunities for treatment exist.

Stereotypes of older people suggest that they are depressed.

To examine depression symptoms among people aged ⩾65 in the general population and to ask the following questions. Are there high proportions of depressive symptoms among otherwise well people? Do these levels reflect the prevalence of depression? Do key symptoms vary with age and do they confirm stereotypes?

Nine centres contributed data from community-based random samples, using standardised methods (GMS–AGECAT package)

Proportions of depressive symptoms varied between centres. Some often associated with ageing were rare. Many were more common in women. Low-prevalence centres tended to have fewer symptoms among ‘well’ people, but there were inconsistencies. Low levels of symptoms among the well population of a centre did not necessarily predict lower levels in the depressed.

Variations in the prevalence of depressive symptoms occurred between centres, not always related to levels of illness. There was no consistent relationship between proportions of symptoms in well persons and cases for all centres. Few symptoms were present in > 60% of the older population – stereotypes of old age were not upheld.

In an 11-country European collaboration, 14 population-based surveys included 21 724 subjects aged ⩾65 years. Most participating centres used the Geriatric Mental State (GMS), but other measures were also used.

To derive from these instruments a common depression symptoms scale, the EURO–D, to allow comparison of risk factor profiles between centres.

Common items were identified from the instruments. Algorithms for fitting items to GMS were derived by observation of item correspondence or expert opinion. The resulting 12-item scale was checked for internal consistency, criterion validity and uniformity of factor-analytic profile.

The EURO–D is internally consistent, capturing the essence of its parent instrument. A two-factor solution seemed appropriate: depression, tearfulness and wishing to die loaded on the first factor (affective suffering), and loss of interest, poor concentration and lack of enjoyment on the second (motivation)

The EURO–D scale should permit valid comparison of risk-factor associations between centres, even if between-centre variation remains difficult to attribute.

Data from surveys involving 21 724 subjects aged ⩾65 years were analysed using a harmonised depression symptom scale, the EURO–D.

To describe and compare the effects of age, gender and mental status on depressive symptoms across Europe.

We tested for the effects of centre, age, gender and marital status on EURO–D score. Between-centre variance was partitioned according to centre characteristics: region, religion and survey instrument used.

EURO–D scores tended to increase with age, women scored higher than men, and widowed and separated subjects scored higher than others. The EURO–D scale could be reduced into two factors: affective suffering, responsible for the gender difference, and motivation, accounting for the positive association with age.

Large between-centre differences in depression symptoms were not explained by demography or by the depression measure used in the survey. Consistent, small effects of age, gender and marital status were observed across Europe. Depression may be overdiagnosed in older persons because of an increase in lack of motivation that may be affectively neutral, and is possibly related to cognitive decline.

Homelessness is a major public health problem among persons with severe mental illness (SMI). Cost-effective programmes that address this problem are needed.

To evaluate the cost-effectiveness of an assertive community treatment (ACT) programme for these persons in Baltimore, Maryland.

A total of 152 homeless persons with SMI were randomly allocated to either ACT or usual services. Direct treatment costs and effectiveness, represented by days of stable housing, were assessed.

Compared with usual care, ACT costs were significantly lower for mental health in-patient days and mental health emergency room care, and significantly higher for mental health out-patient visits and treatment for substance misuse. ACT patients spent 31% more days in stable housing than those receiving usual care. ACT and usual services incurred $242 and $415 respectively in direct treatment costs per day of stable housing, an efficiency ratio of 0. 58 in favour of ACT. Patterns of care and costs varied according to race.

ACT provides a cost-effective approach to reducing homelessness among persons with severe and persistent mental illnesses.

Most individuals who, shortly after trauma, express symptoms of post-traumatic stress disorder (PTSD) recover within one year of their traumatic experiences. In contrast, those who remain ill for one year rarely recover completely. The early identification of the latter is, therefore, very important.

To prospectively evaluate predictors of PTSD at four months and one year.

We followed 236 trauma survivors recruited from admissions to a general hospital's emergency room for four months, at which point 41 (17.4%) met diagnostic criteria for PTSD. Twenty-three of these individuals, and 39 individuals without PTSD at four months, were assessed again at one year.

Depressive symptoms were the best predictors of PTSD at both time points. Intrusive symptoms and peri-traumatic dissociation were better at predicting four-month PTSD than one-year PTSD.

The occurrence of depression during the months that follow a traumatic event is an important mediator of chronicity in PTSD.

Neurobehavioural symptoms are common immediately after a minor head injury but have not been studied one year after the injury.

To estimate the rate and pattern of neurobehavioural symptoms one year after a head injury of varying severity.

Adults who had been hospitalised after a head injury (n=196, 164 of whom had a face-to-face interview) and showed indirect evidence of brain assault were assessed for the presence of neurobehavioural symptoms with the help of a behaviour rating scale.

About 40% had three or more symptoms. Individual symptoms varied among 3% (social disinhibition), 15% (lack of initiative) and 35% (irritability) of the cohort. Premorbid factors such as lower social class and lower educational achievement, head-injury-related factors such a low Glasgow coma score, and outcome-related factors such as the presence of a disability according to the Edinburgh Rehabilitation Status Scale and psychiatric caseness according to the Clinical Interview Schedule–Revised, significantly influenced the rate and the pattern of behavioural symptoms. The pattern of symptoms varied between age groups and according to the severity of the head injury.

A significant proportion of patients with varying degrees of severity of head injury showed behavioural symptoms after one-year of head injury.