A total of 10,247 residents of Tehran were included in thestudy, as previously explained [16]. The population’s aver-age age was 48.2 (16.41), and 46.5% were men. Patientswere divided into seven age groups. The frequencies andpercentages of gender and different age groups are dem-onstrated in Table 1. The age-adjusted prevalence of eachmental symptom in the Tehran population is reportedin Table 2. The prevalence of all MHDs was estimated at37.1% in the Tehran population. The age-adjusted preva-lence of MHDs was significantly higher in women (45.0%)compared to men (28.0%). The most common psychiat-ric symptom was depression, reported in 43.0% (95%CI:40.4, 45.6%) of the population. The least common condi-tion was social dysfunction, detected in 8.1% (95%CI: 6.7,9.6%) of the population.Mental health disorders in each domain according toage and sex groups are reported in Fig. 1. Regarding theage groups, the highest rate of MHDs was reported in the25–34 years and over 75 age group. Notably, the preva-lences of all four psychiatric disorders were higher in thefemale population in all age groups.The prevalence of depression was the highest in the15–24 age group (Fig. 1b). This prevalence decreased inthe next age groups, followed by an increase in partici-pants aged 75 and older. The lowest rate of depression inboth sexes was in the age group 65–74 years. On average,Individuals with depression were four years younger thanthe rest of the population, revealing an overall decreasingtrend for depression by age.The highest rate of anxiety was seen in the age group25–34 years, followed by a relatively neutral trend in thefollowing age groups (Fig. 1c). Somatization disorderswere highest in subjects aged 75 years and older in bothgenders. The lowest rates were reported in women aged15–24 and men aged 45–54 (Fig. 1d). Social dysfunctionwas most prevalent in subjects over 75 years (Fig. 1e).The geographic distribution of four dimensions ofGHQ mental health disorders based on the participants’zipcodes is illustrated in Fig. 2. Depressive disorderswere most commonly reported in the west and south-east of the city. Anxiety disorders were more prevalentin Tehran’s west, northeast, and southeast regions. SocialTable 1 Frequency and percentage of Gender and age groupsin the study populationAge group (year) Women (%) Men (%) Total (%)15–24 488 (4.8) 455 (4.4) 943 (9.2)25–34 519 (5.1) 489 (4.8) 1008 (9.8)35–44 1323 (12.9) 1006 (9.8) 2329 (22.7)45–54 1202 (11.7) 1007 (9.8) 2209 (21.6)55–64 1102 (10.8) 865 (8.4) 1967 (19.2)65–74 600 (5.9) 622 (6.1) 1222 (11.9)75 + 251 (2.4) 318 (3.1) 569 (5.6)Total 5485 (53.5) 4762 (46.5) 10,247 (100)Table 2 Comparison of the age-adjusted prevalence of differentmental health disorders according to the four domains of GHQ-28 by genderCI Confidence interval, GHQ General health questionnaireGHQ Dimension Total (95% CI) Women (95%CI)Men (95% CI)All dimensions, % 37.1 (34.5- 39.6) 45.0 (41.4- 48.6) 28.0 (24.7- 31.6)Depression, % 43.0 (40.4- 45.6) 48.5 (44.9- 52.2) 36.8 (33.2- 40.5)Anxiety, % 40.2 (37.6- 42.8) 48.0 (44.4- 51.6) 31.25 (27.8- 34.9)Somatization, % 30.5 (28.1- 33.0) 40.1 (36.6- 43.7) 19.5 (16.5- 22.6)Social dysfunc-tion, %8.1 (6.7- 9.6) 9.2 (7.2- 11.5) 6.8 (5.1- 9.1)