This cross-sectional study was conducted in the Shahrekord University of Medical Sciences (SKUMS) in autumn 2014. First, the study protocol was approved by the Ethics Committee of the SKUMS (ethics code no. 93-7-14). Moreover, the participants were ensured that information would be kept strictly confidential.

All students of the SKUMS (N:1960) comprised the study population. Sample size was determined to be 148 participants by a formula for cluster sampling considering Z(1-α/2) = 1.96, Z(1-β) = 0.84 and d = 0.23. However, the researchers decided to enroll 156 participants. A stratified sampling method was adopted to determine the number of the participants enrolled from the four faculties under study.

The inclusion criteria were, being student of the SKUMS and completing the questionnaire voluntarily. The students who suffered from psychiatric disorders, took medications, or did not volunteer to complete the questionnaire were excluded from the study.

Students whose parents were relatives were assigned to case group and students with unrelated parents to control group. Couples that were related as second cousins or closer were considered to be consanguineous marriage [4]. The method of sampling was cluster and the number of the participants from each faculty was decided to be proportionate to the number of that faculty’s students. As the desired number of participants was enrolled from a faculty, the researchers discontinued the questionnaire administration to that faculty’s students.

Participants completed two questionnaires consisting of a Socio-Demographic Questionnaire (SDQ) and 28-item General Health Questionnaire (GHQ-28). The SDQ consisted of questions about age, gender, field of study, faculty, level of education, place of residence and parents relatedness. Degree of consanguinity was determined by genetic counselor as parents relatedness. GHQ–28 is a validated and reliable screening tool to investigate mental health. This questionnaire that was developed by Goldberg and Hillier (1979) consists of four subscales: somatic symptoms, anxiety/insomnia, depression symptoms and social function. The Persian version of this questionnaire with confirmed validity (84.2 %) and reliability (85%) according to Noorbala et al., study was administered to the participants [14]. In this study, we used a four-point Likert scale from zero to three with total score ranging from 0 to 84. Score 6 for each subscale and total score of 22 were considered cut-off points. These scores (6 and 22) and higher were determined to represent suspicious cases of mental disorders. Specificity, sensitivity and overall misclassification rate of the cut-off score 6 were 93.8%, 84.7% and 8.2%, respectively [2].

A descriptive and inferential statistics measurement was used for data analysis. Independent t-test and the one-way analysis of variance (ANOVA) were applied to determine significant differences. Odd ratio was used to estimate the relative risk. Relationship between mental health and its subscales with variables was estimated using Pearson correlation. Data analysis was done using the statistical package for the socials sciences, version 19. Generally, a p-value less than 0.05 was considered statistically significant.

The [Table/Fig-1] sets out socio-demographic characteristic of sample. Data analysis showed that there is no significant difference in socio-demographic variable including, gender, field of study, faculty, level of education, place of residence and family income, between case and control groups (p> 0.05).

The student’s age ranged from 18 to 39 years, and the mean (± standard deviation) age of the students in the case and control groups was 21.21±2.76 and 21.83±3.93, respectively, with no significant difference between the two groups (p>0.05).

Descriptive analysis and estimation of odd ratio are showed in [Table/Fig-2]; this results suggest that more than 30% of the individuals (the both case and control groups) were suffering from mental health problems. The most common mental health problems in the both groups was social dysfunction subscale (54.5% in the case group and the control group 50%) and the least in the depression subscale (15.4% in the case group and 17.3% in the control group). A statistically significant difference in frequency between the two cases and control groups were not observed in the overall mental health and its subscales (p> 0.05).

According to [Table/Fig-3] no statistically significant difference in frequency of the overall mental health situation and its subscales was observed among individuals of first cousin marriage, second cousin marriage and distant relative (p> 0.05).

The mean and standard deviation scores of overall mental health and its subscales among individuals of first cousin marriage, second cousin marriage and distant relative are showed in [Table/Fig-4]. According to analysis of variance, there is no significant difference (p> 0.05).

Statistical analysis with Pearson correlation coefficient revealed that no relationship between mental health and its subscales with variables including age, number of children, number of consanguineous marriage in relatives and grade point average in the both case and control groups (p> 0.05) [Table/Fig-5].

This study is the first investigation of association between consanguinity marriage and mental health problems in Iran. According to the World Health Report 2013, more than 25% of total disability and 10% of the global burden of disease belong to mental, neurological and substance use disorders. In Iran after unintentional accidents, mental health problems have second place on the list of the burden of disease [15]. Because of high prevalence and huge burden associated with these diseases, mental health problems are considered as a health priority and investing in mental health to diminish disability and deaths associated with these disorders can produce massive returns [1].

Studies show that some genetic disorders require two copies of the defective gene, the possibility of this condition increased in consanguineous marriage so consanguinity study can be used to suggest autosomal recessive mode of inheritance [16,17]. Previous researches indicate that the risk of recessive disorders is increased in consanguineous marriages. Unfortunately, consanguineous marriages are very common in Iranian population (38% of all marriages); therefore, the investigation of the association between parental consanguinity and mental health is important issue that was not conducted in Iran already. In this study we evaluated the effect of parental consanguinity on college student mental health. This study demonstrated that the status of mental health was not significantly different between the case and control groups (p>0.05). This result suggests that consanguinity may not be associated with mental health problems and the mode of inheritance in these mental health problems may not have recessive or a multigenic pattern. Noorbala et al., study indicated that environmental factors including age, gender, education, occupation, place of residence and marital status had significant effects on mental health [14]. In this study, we evaluated the correlation between mental health and age, number of children and frequency of consanguineous marriage among relatives and found no significant association between mental health and these variables in consanguineous and non-consanguineous parents. In this study, we enrolled 18- to 39-year-old students, but in the study by Noorbala et al., the study population were 15 years and older; therefore, difference in age between the studied participants may account for inconsistency in the findings [14].

Also studies of Ahmed AH, Saugstad L and Chaleby K indicated that no significant association is between psychiatric disorders such as schizophrenia and consanguineous marriage [18–20], so it can be compatible with finding of our study. The most common mental health problem in both groups was social dysfunction subscale and the least common problem was depression subscale; this finding is inconsistent with the study by Noorbala et al., [14]. Differences in age groups, education and other characteristic of samples can be possible reasons for these disagreements. The results of [Table/Fig-2] show that generally more than 30% of the individuals under study had mental health problems; previous epidemiological studies of mental health problems in Iran show rates varying between 11.9% and 23.8%. The cause of difference between rates of present study and other epidemiological studies may be difference in age groups, method and tools of screening and classification system.

A significant correlation was not observed between the subscales and variables of age, number of children, frequency of consanguineous marriage among relatives and average also between GHQ-28 total scale and these variables in the case and the control groups.

The limitation of our study is that, this study was conducted using GHQ-28 that is a screening tool and is not an instrument to conduct structural interviews. Besides that, GHQ-28 has not been developed to investigate the prevalence of different disorders.

The study revealed that social dysfunction was very common among SKUMS students and mental health problems do not tend to occur more frequently in the children of consanguineous parents than in those of non-consanguineous parents. These results suggest that mental health problems may not have recessive or a multigenic pattern of inheritance.