Instruments and measures

All information about menstruation and menopause was obtained during the interviews in 1999 and 2008, when participants were 41 and 50 years old, respectively. Interviews were conducted according to the Structured Psychopathological Interview and Rating of the Social Consequences of Psychological Disturbances for Epidemiology (SPIKE)27. This semi‐structured interview, developed for epidemiological surveys in psychiatric research, assesses data about socio‐demography, psychopathology, substance use, medication, health services use, impairment, and social activity. Its reliability and validity have been reported elsewhere28.

Menopause status was comprehensively assessed in the last interview in 2008. We defined as post‐menopausal those women whose last menstruation had occurred more than 12 months before. We defined as peri‐menopausal those women whose last menstruation had occurred within the past 12 months and who had not menstruated in the preceding two months, and those whose last menstrual cycle had occurred less than one month before and who reported menstrual irregularities. We defined as pre‐menopausal those women whose most recent menstruation had occurred within the past month and who had experienced no menstrual irregularities during the past 12 months.

The following symptoms were assessed by the SPIKE during the 2008 interviews, and were included in our analysis: hot flushes and/or night sweats, sleep disturbances, depressed mood, irritability and/or nervousness, anxiety and/or panic, physical and mental tiredness, sexual problems, urinary incontinence, vaginal dryness, and joint pain. Participants rated distress related to each of these symptoms using a five‐point Likert scale ranging from 1 (“not at all”) to 5 (“extremely”).

We also assessed psychopathology through the SCL‐90‐R, in which distress from each symptom is rated according to a five‐point Likert scale ranging from 1 (“not at all”) to 5 (“extremely”). We covered the most recent four‐week period at each interview. The 90 items of the checklist were grouped into nine subscales (anxiety, depression, hostility, interpersonal sensitivity, obsessive‐compulsivity, paranoid ideation, phobic anxiety, psychoticism, and somatization), with the score on each subscale calculated as the average of the scores on the corresponding items (thus ranging from 1 to 5). Psychopathological vulnerability was evaluated using the mean SCL‐90‐R global severity index of each individual between 1979 and 1999. The SCL‐90‐R has shown good internal consistency and test‐retest reliability29, 30.

Personality was assessed by the Freiburg Personality Inventory31 in 1988, when the women were 30 years old. We utilized an empirically derived subscale of neuroticism consisting of 16 items, which has been found to have good validity and reliability32, 33.

At each interview, the 12‐month prevalence of major depression episode and anxiety disorders was assessed on the basis of the information provided by the SPIKE. The criteria for major depressive episode, agoraphobia, social phobia, specific phobia and obsessive‐compulsive disorder were those of the DSM‐III‐R, whereas the criteria for generalized anxiety disorder and panic disorder were those of the DSM‐III (see Angst et al34 for further information).

The assessment of psychosocial distress was based on participants’ perceived discontent, expressed using a five‐point Likert scale ranging from 1 (“not at all”) to 5 (“extremely”), with six psychosocial domains: employment, financial situation, friendships, health, partnership, and family. Because the intercorrelation of these six variables was high, we used a single variable obtained by computing the mean score across the six domains.