This study was conducted between August and December 2019. Participants were randomly chosen from the general population across Lebanon. Individuals included in this study were aged above 18 years old, having no known history of neurological or psychological impairement. Excluded patients were those with abnormal performances on the HSCT, which have been described in a wide variety of neurological, psychiatric, and neurodevelopmental conditions, such as Alzheimer’s disease and mild cognitive impairment 22-24, brain traumatic injury 25, cerebrovascular accidents26, Parkinson’s disease 27, amyotrophic later sclerosis 28, frontotemporal dementia 28, schizophrenia 29, bipolar disorder 30, and autism spectrum disorder 31. Patients aged above 55 years old 32 underwent a mini mental state examination (MMSE); those obtaining a score of 24 or more were included in the study 33.
Minimal sample size calculation
According to Comrey and Lee 34, a minimal sample of 5-10 observations is needed per item of the scale in order to validate a scale. Therefore, a minimum of 300 participants was needed for adequate statistical power, since the assessment of the automatic and inhibition conditions included 15 items each.
Questionnaires and variables
Data was collected via a personal interview, and subjects were tested with only one examiner in a quiet office. The first section assesses the socio-demographic characteristics, including age, gender, region, the number of rooms in the household and the number of persons living in it, the level of education, the number of mastered languages, the monthly income, and the medical history and chronic treatments.
The second section evaluates the diet of each participant, taking into consideration vegetables, fruits, dairy products, breakfast, eating 5 meals per day, sweets consumption, red meat, beverages, and fast food. Each variable is scored between 1 and 5 to get a minimum score of 9 and a maximum score of 45; higher scores indicate a healthier diet. This scale was inspired by the constituants of the DASH diet (Dietry Approaches to Stop Hypertension) 35.
The third section is the Arabic translation of the short form of International Physical Activity Questionnaire (IPAQ) 36 that asks about three specific types of activities: walking, moderate-intensity activities, and vigorous-intensity activities. Then participants are classsified to have low, moderate, or high physical acitivity.
To be classified as ‘moderate’, participants should match one of the following:
a) 3 days of vigorous-intensity activity for a minimum of 20 minutes per day.
b) 5 days of moderate-intensity activity and/or walking for a minimum of 30 minutes per day.
c) 5 days of any combination of walking, moderate-intensity or vigorous intensity activities, achieving at least a total physical activity of 600 minutes/week.
To be classified as ‘high’, participants should match one of the following:
a) vigorous-intensity activity 3 days, achieving at least 1500 minutes/week.
b)7 days of any combination of walking, moderate-intensity or vigorous-intensity activities of at least 3000 minutes/week.
Participants who did not meet the above criteria were considered to have a ‘low’ physical activity level 36.
The fourth section assesses the exposure to polluted air; participants are asked about the environment where they live, the heating system used (wood, gas, electricity), if they are living or working next to factories or power stations, and their exposure to cigarette smoking.
The fifth section represents the Arabic translation of the Short Version of the Problematic Mobile Phone Use Questionnaire (PMPUQ-SV), containing 15 items that are scored from 1 (‘I strongly agree’) to 4 (‘I strongly disagree’), except for 8 items that are reversly scored. Overall scores range from 15 to 60, with higher scores indicating a higher risk for problematic mobile phone use 37.
The Hayling Sentence Completion Test
The HSCT was translated to Arabic and adapted to the linguistic and cultural realities of the Lebanese population. The A-HSCT consists of two conditions (аutomatic and inhibition), for which two different groups of 15 sentences are given. In both conditions, the interviewer reads out loud the unfinished sentences, and the pаrticipant has to complete each sentence with one word 4.
The participants are requested to give a word that is related to the beginning of the sentence, and should do so as quickly аs possible. For example, “He mailed the letter without а . . . (participant says) stamp.” Time latency in automatic condition measures the participant’s rapidity in initiating an automatic response. According to the scoring system, three error points are scored when participants provide an incorrect word, one point when the answer is semantically related to the sentence, and no error point if the correct word is given. Higher error score corresponds to a lower performance 4.
The participants are requested to complete the sentence аs fast as they can with a word that is completely unlinked to it, which makes no sense at all in the context of the sentence. For example, “The captain wanted to stay with the sinking . . . (pаrticipant says) apple.” If at any time during this condition the subject completes the sentence correctly instead of using an unrelated word, s/he is told thаt the word is too linked to the sentence and is retold the task instructions. Time latency in inhibition condition gives information about the time needed to inhibit the correct response and find an incorrect one 4. According to the scoring system, three points are given when the sentence is completed with the answer that fits with it. One point is given when a subject gives an antonym, a semantically related word, or a word that makes a vague reference to the sentence. Participants receive zero points when a totally unrelated word is provided. A higher error score indicates a lower performance 4.
The total time to complete both conditions of the A-HSCT was approximately five minutes. The automatic condition was tested prior to the inhibition section. Two practice sentences were initially presented prior to each condition. Time of response latency was measured and collected using a stopwatch in both conditions; the timing began soon after the tester finished the sentence, and was stopped soon after the participant began their answer. Response latencies were recorded in whole second units and were not rounded up. For instance, a time between 0 and 0.99 was scored as 0. An average response latency score of all the individual’s latencies for each condition was then computed based on all responses, including errors. No time limit was given for responding. We also scored errors to evaluate the efficacy of the strategy elaborated by the participant to give an incorrect response 4. A simple guideline for the error scoring of the inhibition condition was created, containing a collection of several hundreds of errors for each sentence 5. All sections of the questionnaire were translated to Arabic by a translation specialist, then the translation was retranslated to its original language by another specialist. Upon fullfilment of this procedure, the translators compared the versions of every scale to determine whether the variables had the same meaning. No major incompatibilities were found between the two versions for all scales; they were resolved by consensus.
Statistical Package for Social Science (SPSS) version 23 was used for the statistical analyses. A principal component analysis, using a promax rotation since the questions of the scales were correlated, was conducted in order to validate the automatic and inhibition parts of the HSCT. Adequacy of the sample was confirmed through the Kaiser–Meyer–Olkin (KMO) index, Bartlett’s Chi-square test of sphericity and scree plot. Factors with an Eigenvalue higher than one were retained. The Student t-test was used to compare two means, whereas the Pearson correlation was used to study the association between two continuous variables. Multivariable linear regression models were done to explore factors associated with the response-time and the number of errors taken as dependent variables and taking all variables that showed a p<0.05 in the bivariate analysis as independent variables. A p<0.05 was considered significant. Reliability was assessed using Cronbach’s alpha.