In this cross-sectional study, 266 women aged 18–50 with history of migraine headaches were selected from two neurology clinics in Tehran. The sample size was computed according to the following formula: n= [(Z 1-α + Z 1-β) × √1-r2]/r) 2 + 2), which r = 0.25, β = 0.95, and α = 0.05 . Based on this formula, 241 individuals were required; however, due to the availability of data and to account for any possible exclusion, 266 individuals were included.
In the present study, Inclusion criteria were the following: participants with history of migraine headaches diagnosed by an expert neurologist, voluntarily involvement, BMI ranged between 18.5 and 30, and visiting the clinics for the first time. Consent forms were collected by all of the participants.
MIND diet assessment
Dietary intake was evaluated by a face- to- face interview using a 147-items semi-quantitative food frequency questionnaire (FFQ), which its reliability and validity had been already approved in Iran . To compute the MIND diet scores, some dietary components of the FFQ was used in this study which are presented in Table 1. Of 15 dietary factors in the original scoring of MIND diet, 10 of them were defined as brain healthy food groups (green leafy vegetables, other vegetables, nuts, berries, beans, whole grains, fish, poultry, olive oil, and wine) and 5 as brain unhealthy food groups (red meats, butter and stick margarine, cheese, pastries and sweets, and fried/fast food) . However, in the current study we used a modified MIND diet scoring based on Iranian food habits . In this scoring, wine consumption was not considered (forbidden drinking). The other 14 food groups were applied in the MIND scoring. First, Individuals were categorized according to tertile categories of dietary intakes. Participants in the bottom tertile of brain healthy food groups were given the score of 0, those in the middle tertile were given the score of 0.5 and individuals in the top tertile were given the score of 1. On the other hand, we did vice versa about brain unhealthy food groups. Finally, the overall score was computed by summing up of all dietary components scores. Therefore, the participant's MIND diet score ranged from 0 to 14.
MIDAS and VAS questionnaires
To assess headache-related disability, the Migraine Disability Assessment (MIDAS) questionnaire was applied. The MIDAS questionnaire validity and reliability already were assessed in Iranian population . The VAS score cut-off points ranged from 1 to 10 and categorized pain severity in three levels: 1 to 3 (mild pain), 4 to 7 (moderate pain) and 8 to 10 (severe pain) .
Assessment of other variables
Weight was measured via a digital scale (SECA, Hamburg, Germany) to the nearest 0.1 kg, while wearing no shoes and one layer of clothing. To examine physical activity (PA), International Physical Activity Questionnaire (IPAC), was used . PA was shown as metabolic equivalent hours per week (METs h/week).
The chi-square test was used to assess the association between the quartiles of MIND diet and qualitative variables. In addition, one-way analysis of variance (ANOVA) was used to assess the association between the quartiles of MIND diet and quantitative variables. Covariance analysis (ANCOVA) was applied to compare the dietary intakes of participants among quartiles of MIND diet by adjusting the effect of total energy. Confounding factors including total energy, age, BMI, PA, smoking status, water intake, salt intake, medication usage, and menstruation headaches were applied in adjusted models. To assess the association between the MIND score quartiles and the headache severity and disability, multinomial logistic regression model was used in crude and adjusted models. Moreover, to determine the association between headache duration and frequency (dependent variable) and the quartiles of MIND diet (independent variables), Linear Regression Models analysis was used, in crude and adjusted models. P < 0.05 was considered as level of statistically significance. SPSS version 24 (SPSS Inc., Chicago, IL, USA) was used to perform statistical analysis.