in iran , adolescents use the internet more than any other age group . for this age group , the internet is not only the most common activity of daily life but also a major recreational activity . by 2009 , some 98% of iranian adults between the age of 20 and 30 years had used the internet . in recent years , with the greater availability of the internet , internet addiction has become an increasing mental problem among adolescents . several countries in asia , particularly china , south korea , and taiwan , have been reported to have the highest incidence of computer or internet addiction among young people . the prevalence of internet addiction among iranian college students has increased markedly . in recent years , the incidence of it has been estimated to vary from 3.8% to 30% among the iranian youth.[47 ] adolescents are more vulnerable to pathologic internet use as they have less ability to control their enthusiasm for something that awakens their interests , such as internet or computer games . the continuous escape from real life into virtual space is often associated with serious problems in daily life for adolescents . psychologists and educators are aware of the potential negative impact of the excessive use of internet and related physical and psychological problems . many studies have reported associations between internet addiction , psychiatric symptoms , and depression among adolescents.[1113 ] some studies have focused on the impact of addiction to internet at a descriptive level of psychopathology with psychological variables such as loneliness and self - esteem . jeon ( 2005 ) investigated the effect of the extent of internet use , depression and self - esteem in 800 adolescents , and concluded that large extent of internet use increases depression and decreases self - esteem . you ( 2007 ) analyzed the effect of internet addiction on 400 elementary school students self - esteem and depression . the relationship between internet addiction and self - esteem indicates a statistically significant negative slope ( r=0.284 , p<0.01 ) . in other words , the higher the internet addiction , the lower the self - esteem . in spite of the fact that many researchers have investigated the effect of internet addiction on psychiatric symptoms such as depression and anxiety , there are very few studies focusing on the impact of compulsive internet use on other psychiatric symptoms such as somatization and psychosis . also , past studies have achieved contradictory results and the observed findings are quite limited . therefore , it is necessary to identify the pattern of internet use and examine the effect of internet addiction on other psychiatric symptoms such as phobia , psychosis , and somatization , and moreover , to explore the psychological features of pathological internet use . in the future , we will be confronted with problems arising from internet addiction and overuse in iran which can impact on youth mental health . thus , the aim of this study was to evaluate the impact of internet addiction on psychiatric symptoms by controlling for the effects of demographic variables such as age , gender , marital status , amount of hours of internet use , etc . the samples of this study consisted of 250 students who were randomly selected from four universities in the city of isfahan including isfahan university ( n=72 ) , isfahan university of medical sciences ( n=38 ) , islamic azad university ( n=58 ) and isfahan university of technology ( n=82 ) . they had an age range of 20 - 30 years ( mean=20 , sd=2.1 ) , and had used the internet at least once a month in the previous 6 months . the inclusion criteria were : 1 ) being a student during the study period , 2 ) aged between 18 and 30 years , 3 ) using internet at least once a day for the past 6 months . the exclusion criteria were 1 ) severe physical problems or apparent disability and 2 ) the persons who were under treatment due to a specific psychiatric disorder during the past year . to measure the level of internet addiction , we used a valid and reliable persian version of young diagnostic questionnaire ( ydq ) and young internet addiction test ( iat ) and also conducted a semi - structured interview based on dsm - iv - tr criteria for impulse control disorder not otherwise specified ( icd - nos ) . ydq , which consists of eight  yes  or  no  questions , was translated into farsi . subjects who answered  yes  to five or more of the questions over a 6-month period were considered  addicted  . respondents who answered  yes  to questions 15 and at least one of the remaining three questions were classified as suffering from internet addiction . in previous publications about ydq , in out study , we chose the modified ydq , which had a good reliability and a test - retest of 0.82 after 2 weeks . iat is a 20-item self - report and 5-point scale based on the dsm - iv diagnostic criteria for compulsive gambling and alcoholism . in the present study , we used the persian version of iat , which had a good reliability with a cronbach 's alpha of 0.89 and test  retest of 0.68 after 2 weeks . symptom checklist-90-revision ( scl-90-r ) is a multidimensional self - report symptom inventory developed by derogatis et al . , and its derived iranian standard version was used in this study . the scl-90-r consists of 90 questions in total , which are divided into nine symptom dimensions : somatization , obsessive  compulsive disorder ( ocd ) , interpersonal sensitivity , depression , anxiety , hostility , phobic anxiety , paranoid ideation and psychoticism . the nine symptom dimensions were divided into three global indexes , namely , the global severity index ( gsi ) representing the extent or depth of the present psychiatric disturbance , positive symptom total ( pst ) representing the number of questions rated above 1 point , and positive symptom distress index ( psdi ) representing the intensity of the symptoms . in this study , the iranian version of scl-90-r had an acceptable reliability with a cronbach 's alpha of 0.95 and split - half reliability of 0.88 . semi - structured interview based on dsm - iv - tr criteria for icd - nos was performed by a psychiatrist trained for the diagnosis and treatment of icd in general and internet addiction disorder in particular . we used t - test and multivariate analysis of covariance ( mancova ) for the analyses of research questions by spss16 software . to measure the level of internet addiction , we used a valid and reliable persian version of young diagnostic questionnaire ( ydq ) and young internet addiction test ( iat ) and also conducted a semi - structured interview based on dsm - iv - tr criteria for impulse control disorder not otherwise specified ( icd - nos ) . ydq , which consists of eight  yes  or  no  questions , was translated into farsi . subjects who answered  yes  to five or more of the questions over a 6-month period were considered  addicted  . respondents who answered  yes  to questions 15 and at least one of the remaining three questions were classified as suffering from internet addiction . in previous publications about ydq , in out study , we chose the modified ydq , which had a good reliability and a test - retest of 0.82 after 2 weeks . iat is a 20-item self - report and 5-point scale based on the dsm - iv diagnostic criteria for compulsive gambling and alcoholism . in the present study , we used the persian version of iat , which had a good reliability with a cronbach 's alpha of 0.89 and test  retest of 0.68 after 2 weeks . symptom checklist-90-revision ( scl-90-r ) is a multidimensional self - report symptom inventory developed by derogatis et al . , and its derived iranian standard version was used in this study . the scl-90-r consists of 90 questions in total , which are divided into nine symptom dimensions : somatization , obsessive  compulsive disorder ( ocd ) , interpersonal sensitivity , depression , anxiety , hostility , phobic anxiety , paranoid ideation and psychoticism . the nine symptom dimensions were divided into three global indexes , namely , the global severity index ( gsi ) representing the extent or depth of the present psychiatric disturbance , positive symptom total ( pst ) representing the number of questions rated above 1 point , and positive symptom distress index ( psdi ) representing the intensity of the symptoms . in this study , the iranian version of scl-90-r had an acceptable reliability with a cronbach 's alpha of 0.95 and split - half reliability of 0.88 . semi - structured interview based on dsm - iv - tr criteria for icd - nos was performed by a psychiatrist trained for the diagnosis and treatment of icd in general and internet addiction disorder in particular . we used t - test and multivariate analysis of covariance ( mancova ) for the analyses of research questions by spss16 software . among the 250 university students , the majority of internet users were males ( 61.7% males , 38.3% females ) . according to the iat , modified ydq criteria by beard and clinical interview , 15% of the samples were suffering from internet addiction and 85% of the participants were identified as normal users . regarding the educational level , most of the internet users were undergraduate students . in total , the participants were matched by gender , age , educational levels and other socio - demographic variables . results demonstrated that adolescents with internet addiction had higher scores of gsi , pst , psdi and all dimensions of scl-90 questionnaire . the t - test results indicated that the two groups differed significantly in all dimensions of psychiatric symptoms [ somatization , ocd , interpersonal sensitivity , depression , anxiety , aggression ( hostility ) , phobia , paranoia , psychosis and gsi , pst , psdi ] ( p<0.01 ) . also , mancova model with auxiliary variables , such as marital status , age , education , and length of internet usage , was utilized to analyze the relationship between internet addiction and psychiatric symptoms . after omitting non - influential variables in the final model , gender was considered as a moderator variable . the results showed that internet addiction affected psychiatric symptoms by controlling sex [ wilk 's lambda value=0.79 , f ( 9,107)=3.03 , p<0.01 ] [ table 1 ] . the purpose of this study was to analyze the consequences of internet addiction among a sample of youths and to find the psychiatric effects resulting from excessive internet use . the results of this study provide fundamental information that can contribute to the prevention , diagnosis and treatment of internet addiction among the youth . based on our goal and hypothesis , the means of psychiatric symptoms in the addicted group and non - addicts were compared . this means that normal users are better in terms of mental health in comparison with the addicted group . in addition , internet addicts had various comorbid psychiatric disorders when compared to non - addicted individuals . this means that the group with severe internet addiction had higher scores in all dimensions of psychiatric symptoms , which suggests that addiction could have a negative effect on the mental health status of youth . previous reports demonstrate that 813% of undergraduates are addicted to the internet , which has impaired individual psychological well - being or mental health , peer and family interactions , and academic performance among them . moreover , the internet addict group had the lowest score in health promotion lifestyle profile and perceived health status , which suggests that the addiction could have a negative effect on the health status of adolescents.[2227 ] furthermore , findings also demonstrate that the addict group generally displays higher levels of psychiatric disorders such as depressive mood , anxiety , phobic anxiety , compulsiveness , somatization , etc . research on patients who were addicted to the internet , particularly to the massively multiplayer online role - playing games ( mmorpgs ) , demonstrated that these games induced seizures in 10 patients . yen et al . reported that adolescents with internet addiction as well as those with substance drug use problems had significantly higher scores in the global pathology indices of the ( bsi ) brief symptom inventory gsi , pst , psdi and in other dimensions , such as hostility , depression , phobic anxiety and additional symptoms . it can be concluded that the longer the hours of internet use , the higher the score of psychiatric symptoms . also , it is expected that the increase in psychiatric symptoms leads to a deterioration of mental health . the mentioned finding highly suggests that the symptoms in individuals with internet addiction are an indication of their compulsive thinking and behavior , especially as addiction is defined as uncontrollable compulsive dependence on a substance ( drug ) , behavior , etc . these findings suggest that the internet may provide an environment to escape from stress in the real world for individuals , who seem to be more vulnerable to aggressive behavior and interpersonal dangers than others . but the causal relationship between hostility ( aggression ) and internet addiction needs to be further evaluated in prospective and longitudinal studies . despite these findings , there are studies that show no relationship between the psychiatric symptoms , such as depression , social anxiety , frustration , and internet addiction.[3436 ] this may be due to methodological problems or the definitions and criteria used to diagnose internet addiction disorder in different societies and various studies . based on the aforementioned studies , it is difficult to draw the conclusion that heavy use of the internet results in an overall negative impact on addicts lives . just one negative impact can conclusively lead to interference with subjects activities such as academic work , professional performance , daily routines , and mental health . also , it is not clear whether excessive use of internet is the cause or the consequence of mental problems . findings on the impacts of heavy internet use on mental health of addicts are inconclusive . however , the general health of internet addicts is more at risk than that of normal users . although this study shows some significant differences of scores of psychiatric symptoms between the internet addicted and non - addicted college students , it does have some limitations which should be addressed . first , the cross - sectional research design limited the possibility of drawing conclusions regarding causal relationships . second , the data were collected over a very short period of time and the questionnaires ( ydq , iat and scl-90 ) had their own restrictions . another limitation of this study is that the procedure for selecting the sample did not allow us to generalize the results to the non - college population . most importantly , we were unable to control or measure the length of time the individuals had been using the internet excessively , therefore the effect of excessive internet usage over an extended period of time on an individual 's psychological and physical well - being could not be assessed . longitudinal studies on the long - term effects of excessive internet use would be useful to discover the causal relationship between addiction and depression or other symptoms . although this study shows some significant differences of scores of psychiatric symptoms between the internet addicted and non - addicted college students , it does have some limitations which should be addressed . first , the cross - sectional research design limited the possibility of drawing conclusions regarding causal relationships . second , the data were collected over a very short period of time and the questionnaires ( ydq , iat and scl-90 ) had their own restrictions . another limitation of this study is that the procedure for selecting the sample did not allow us to generalize the results to the non - college population . most importantly , we were unable to control or measure the length of time the individuals had been using the internet excessively , therefore the effect of excessive internet usage over an extended period of time on an individual 's psychological and physical well - being could not be assessed . longitudinal studies on the long - term effects of excessive internet use would be useful to discover the causal relationship between addiction and depression or other symptoms . finally , it should be noted that internet is not an enemy , but people become dependent upon it for various reasons and they might ultimately become detached from the real word . as prevention is better than treatment , and considering the results of this study , this phenomenon should be considered as a psychological problem that has gripped the younger generation who are expected to develop the future society . the correct use of internet can be substituted for wrong ways through appropriate education at home , schools and the university .
background : this study aimed to investigate the impact of internet addiction on some psychiatric symptoms among university students.methods:this cross - sectional study was conducted among 250 students selected via quota sampling from universities in isfahan , iran . 
 participants completed demographic questionnaire , young diagnostic questionnaire , internet addiction test and symptom checklist-90-revision ( scl-90-r ) . 
 finally , the means of psychiatric symptoms of internet addicted and non - addicted subjects were compared . also , t - test and multivariate analysis of covariance were used through spss16 software for data analysis.results:the meanstandard deviation ( sd ) of psychiatric symptoms such as somatization , obsessive  compulsive disorder , interpersonal sensitivity , depression , anxiety , aggression ( hostility ) , phobic anxiety , paranoid ideation and psychoticism in the addicted group were 11.27  6.66 , 14.05  7.91 , 10.5  6.20 , 15.61  8.88 , 10.77  5.52 , 6.77  4.88 , 6.05  4.47 , 7.61  4.28 , and 9.66  6.87 , respectively , and in the non - addicted group were 6.99  6.42 , 7.49  5.23 , 5.46  4.95 , 9.27  7.92 , 6.35  6.69 , 3.57  3.35 , 2.41  2.79 , 5.47  4.1 , and 5.29  4.95 , respectively . 
 there were significant differences between the means of psychiatric symptoms in all scl-90-r subscales and global severity index , positive symptom distress index , positive symptom total in the addicted and non - addicted individuals ( p<0.05 ) . 
 also , internet addiction ( with controlling sex variable ) seemed to affect psychiatric symptoms.conclusion:psychiatrists and psychologists involved in the field of mental health need to be well informed about mental problems due to internet addiction , such as anxiety , depression , aggression , and job and educational dissatisfaction .