Introduction
Post-traumatic stress disorder (PTSD) is a common psychiatric disorder that occurs after direct or indirect experiencing a traumatic event. It is conceptualized by four major groups of symptoms, including re-experiencing of traumatic stimuli, hyper vigilance, avoidance behavior, negative changes in cognition and mood. There is a non-invasive brain stimulation method called repetitive trans cranial magnetic stimulation (rTMS) for patients with PTSD that can modulate cognitive function. Cognitive functioning involves a wide range of mental processes, such as cognitive flexibility, problem-solving, attention, and memory. High-frequency rTMS on the left hemisphere can improve the cognitive functioning of patients with severe PTSD and traumatic brain injury. The present study aims to investigate the effects of high-frequency rTMS on the cognitive functioning of male police officers suffering from PTSD in Iran. 

Methods
The study population includes all male military personnel of the Police Force of the Islamic Republic of Iran (NAJA), referred to the neuropsychiatry department of NAJA’s Imam Sajjad Hospital in Tehran, Iran. Of these, 30 diagnosed with PTSD were selected by a convenience sampling method and randomly divided into two groups of intervention and control. The demographic data, including age, history of the disease, cause of the disease, and used medications were first recorded. Then, PTSD was diagnosed by a neuropsychiatrist, working in the neuropsychiatry department of the hospital. For confirmation, an interview based on the diagnostic and statistical manual of mental disorders, fifth edition (DSM-5), a semi-structured clinical interview for the DSM, and the 24-item perceived stress scale. Rey’s visual memory test (VMT), Rey’s auditory verbal learning test (AVLT), Tower of London test (TLT), and Stroop test, and Wisconsin card sorting test were carried out in the pre-test and post-test phases for both groups. The intervention group was exposed to 20-Hz rTMS at 10 sessions, including 5 seconds of stimulation and 20 seconds of rest interval between each stimulation (1000 pulses per session). Data were analyzed using the multivariate analysis of covariance (MANCOVA) in SPSS software, version 22.

Results
The mean age of 30 participants was 50.16±8.16 years, 50.36±11.28 years for the intervention group and 49.96±6.17 years for the control group. Based on the results, since P<0.05, the results of MANCOVA was significant, indicating a significant difference at least in one of the study variables between the two groups. The results of between-group effects showed a significant difference between the two groups in all variables of total VMT (F=19.385), total AVLT (F=51.527), total TLT (F=10.601), residual error (F=11.929), number of the designs (F=36.819), interference score (F=17.506), interference time (F=5.053), congruent error (F=31.710), and incongruent error (F=13.728) (P<0.05), where the intervention group showed better scores than the control group.

Conclusion
Results showed that the military men with PTSD received high-frequency rTMS had higher scores in the VMT and AVLT than the controls. The results are consistent with the findings of most studies in this field that has been reported that high-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) can improve cognitive functioning in patients with PTSD and traumatic brain injury. PTSD is peculiarly a cognitive and memory disorder. One of the important roles of DLPFC is in executive functioning, such as working memory, cognitive flexibility, planning, inhibitory control, and reasoning; however, the DLPFC is not exclusively responsible for executive functioning. All complex mental activities require some additional cortical and subcortical circuits, to which the DLPFC is connected. There were some limitations in the present study, such as problems in choosing a treatment protocol, studying a limited number of executive functions, and using a quasi-experimental design. In this regard, future studies are recommended to apply other treatment protocols assess more components of executive functioning on other populations, using an experimental design.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the ethics committee of Tabriz University of Medical Sciences (Code:  IR.TABRIZU.REC.1401.046)

Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Authors contributions
Conceptualization, data collection: Saber Heydarpour, Leila Mehdizadeh Fanid; Data collection: Zahra Mirza Asgari; Data analysis, initial draft preparation, editing & review: All authors.

Conflicts of interest
The authors declared no conflict of interest.

References

1. American Psychiatric Association. Diagnostic and statistical manual of mental disorders: DSM-5. Washington: American Psychiatric Publishing, Inc; 2013. [Link]
2. Martin P. The epidemiology of anxiety disorders: A review. Dialogues in Clinical Neuroscience. 2003; 5(3):281-98. [DOI:10.31887/DCNS.2003.5.3/pmartin] [PMID] [PMCID]
3. Morina N, Stam K, Pollet TV, Priebe S. Prevalence of depression and posttraumatic stress disorder in adult civilian survivors of war who stay in war-afflicted regions. A systematic review and meta-analysis of epidemiological studies. Journal of Affective Disorders. 2018; 239:328-38. [DOI:10.1016/j.jad.2018.07.027] [PMID]
4. Bryant RA, Creamer M, O'Donnell M, Forbes D, McFarlane AC, Silove D, et al. Acute and chronic posttraumatic stress symptoms in the emergence of posttraumatic stress disorder: A network analysis. JAMA Psychiatry. 2017; 74(2):135-42. [DOI:10.1001/jamapsychiatry.2016.3470] [PMID]
5. Flory JD, Yehuda R. Comorbidity between post-traumatic stress disorder and major depressive disorder: Alternative explanations and treatment considerations. Dialogues in Clinical Neuroscience. 2015; 17(2):141-150. [DOI:10.31887/DCNS.2015.17.2/jflory] [PMID] [PMCID]
6. Nichter B, Haller M, Norman S, Pietrzak RH. Risk and protective factors associated with comorbid PTSD and depression in U.S. military veterans: Results from the National Health and Resilience in Veterans Study. Journal of Psychiatric Research. 2020; 121:56-61. [DOI:10.1016/j.jpsychires.2019.11.008] [PMID]
7. Lee DJ, Schnitzlein CW, Wolf JP, Vythilingam M, Rasmusson AM, Hoge CW. Psychotherapy versus pharmacotherapy for posttraumatic stress disorder: Systemic review and meta-analyses to determine first-line treatments. Depression and Anxiety. 2016; 33(9):792-806. [DOI:10.1002/da.22511] [PMID]
8. Philip NS, Barredo J, van 't Wout-Frank M, Tyrka AR, Price LH, Carpenter LL. Network mechanisms of clinical response to transcranial magnetic stimulation in posttraumatic stress disorder and major depressive disorder. Biological Psychiatry. 2018; 83(3):263-72. [DOI:10.1016/j.biopsych.2017.07.021] [PMID] [PMCID]
9. Milad MR, Quirk GJ. Fear extinction as a model for translational neuroscience: Ten years of progress. Annual Review of Psychology. 2012; 63:129-51. [DOI:10.1146/annurev.psych.121208.131631] [PMID] [PMCID]
10. Quirk GJ, Garcia R, González-Lima F. Prefrontal mechanisms in extinction of conditioned fear. Biological Psychiatry. 2006; 60(4):337-43. [DOI:10.1016/j.biopsych.2006.03.010] [PMID]
11. VanElzakker MB, Dahlgren MK, Davis FC, Dubois S, Shin LM. From Pavlov to PTSD: the extinction of conditioned fear in rodents, humans, and anxiety disorders. Neurobiology of Learning and Memory. 2014; 113:3-18. [DOI:10.1016/j.nlm.2013.11.014] [PMID] [PMCID]
12. Qin S, Hermans EJ, van Marle HJ, Luo J, Fernández G. Acute psychological stress reduces working memory-related activity in the dorsolateral prefrontal cortex. Biological Psychiatry. 2009; 66(1):25-32. [DOI:10.1016/j.biopsych.2009.03.006] [PMID]

13. Cohen H, Kaplan Z, Kotler M, Kouperman I, Moisa R, Grisaru N. Repetitive transcranial magnetic stimulation of the right dorsolateral prefrontal cortex in posttraumatic stress disorder: A double-blind, placebo-controlled study. The American Journal of Psychiatry. 2004; 161(3):515-24. [DOI:10.1176/appi.ajp.161.3.515] [PMID]
14. Baldauf D, Desimone R. Neural mechanisms of object-based attention. Science. 2014; 344(6182):424-7. [DOI:10.1126/science.1247003] [PMID]
15. Takahashi E, Ohki K, Kim DS. Dissociation and convergence of the dorsal and ventral visual working memory streams in the human prefrontal cortex. Neuroimage. 2013; 65:488-98.  [DOI:10.1016/j.neuroimage.2012.10.002] [PMID] [PMCID]
16. Kaplan JT, Gimbel SI, Harris S. Neural correlates of maintaining one›s political beliefs in the face of counterevidence. Scientific Reports. 2016; 6:39589. [DOI:10.1038/srep39589] [PMID] [PMCID]
17. Hale JB, Fiorello CA. School neuropsychology: A practitioner›s handbook. New York: Guilford Press. 2017. [Link]
18. George MS, Nahas Z, Kozel FA, Li X, Denslow S, Yamanaka K, et al. Mechanisms and state of the art of transcranial magnetic stimulation. The Journal of ECT. 2002; 18(4):170-81. [DOI:10.1097/00124509-200212000-00002] [PMID]
19. Karsen EF, Watts BV, Holtzheimer PE. Review of the effectiveness of transcranial magnetic stimulation for post-traumatic stress disorder. Brain Stimulation. 2014; 7(2):151-7. [DOI:10.1016/j.brs.2013.10.006] [PMID]
20. Trevizol AP, Barros MD, Silva PO, Osuch E, Cordeiro Q, Shiozawa P. Transcranial magnetic stimulation for posttraumatic stress disorder: an updated systematic review and meta-analysis. Trends in Psychiatry and Psychotherapy. 2016; 38(1):50-5.  [DOI:10.1590/2237-6089-2015-0072] [PMID]
21. Cirillo P, Gold AK, Nardi AE, Ornelas AC, Nierenberg AA, Camprodon J, et al. Transcranial magnetic stimulation in anxiety and trauma-related disorders: A systematic review and meta-analysis. Brain and Behavior. 2019; 9(6):e01284. [DOI:10.1002/brb3.1284]
22. Yan T, Xie Q, Zheng Z, Zou K, Wang L. Different frequency repetitive transcranial magnetic stimulation (rTMS) for posttraumatic stress disorder (PTSD): A systematic review and meta-analysis. Journal of Psychiatric Research. 2017; 89:125-35.  [DOI:10.1016/j.jpsychires.2017.02.021] [PMID]
23. Freire RC, Cabrera-Abreu C, Milev R. Neurostimulation in anxiety disorders, post-traumatic stress disorder, and obsessive-compulsive disorder. Advances in Experimental Medicine and Biology. 2020; 1191:331-346. [DOI:10.1007/978-981-32-9705-0_18] [PMID]
24. Hauer L, Sellner J, Brigo F, Trinka E, Sebastianelli L, Saltuari L, et al. Effects of repetitive transcranial magnetic stimulation over prefrontal cortex on attention in psychiatric disorders: A systematic review. Journal of Clinical Medicine. 2019; 8(4):416.  [DOI:10.3390/jcm8040416] [PMID] [PMCID]
25. Lopes R, Fernandes L. Bipolar disorder: Clinical perspectives and implications with cognitive dysfunction and dementia. Depression Research and Treatment. 2012; 2012:275957. [DOI:10.1155/2012/275957] [PMID] [PMCID]
26. Harvey PD, Gould F. Cognitive functioning and disability in post-traumatic stress disorder. Oxford: Oxford University Press; 2018. [Link]
27. Neville IS, Hayashi CY, El Hajj SA, Zaninotto AL, Sabino JP, Sousa LM Jr, et al. Repetitive transcranial magnetic stimulation (rTMS) for the cognitive rehabilitation of traumatic brain injury (TBI) victims: Study protocol for a randomized controlled trial. Trials. 2015; 16:440. [DOI:10.1186/s13063-015-0944-2] [PMID] [PMCID]
28. Leung A, Metzger-Smith V, He Y, Cordero J, Ehlert B, Song D, et al. Left dorsolateral prefrontal cortex rTMS in alleviating MTBI related headaches and depressive symptoms. Neuromodulation. 2018; 21(4):390-401. [DOI:10.1111/ner.12615] [PMID]
29. Leung A, Shukla S, Fallah A, Song D, Lin L, Golshan S, et al. Repetitive transcranial magnetic stimulation in managing mild traumatic brain injury-related headaches. Neuromodulation. 2016; 19(2):133-41. [DOI:10.1111/ner.12364] [PMID]
30. Koski L, Kolivakis T, Yu C, Chen JK, Delaney S, Ptito A. Noninvasive brain stimulation for persistent postconcussion symptoms in mild traumatic brain injury. Journal of Neurotrauma. 2015; 32(1):38-44. [DOI:10.1089/neu.2014.3449] [PMID]
31. Levkovitz Y, Rabany L, Harel EV, Zangen A. Deep transcranial magnetic stimulation add-on for treatment of negative symptoms and cognitive deficits of schizophrenia: A feasibility study.  The International Journal of Neuropsychopharmacology. 2011; 14(7):991-6. [DOI:10.1017/S1461145711000642] [PMID]
32. Drumond Marra HL, Myczkowski ML, Maia Memória C, Arnaut D, Leite Ribeiro P, Sardinha Mansur CG, et al. Transcranial magnetic stimulation to address mild cognitive impairment in the elderly: A randomized controlled study. Behavioural Neurology. 2015; 2015:287843. [DOI:10.1155/2015/287843] [PMID] [PMCID]
33. Dosti P, Khaltabari J, Basri A, Parvin Gonabadi B. [The comparison effectiveness indigenous model of Acceptance and Commitment Therapy focused on compassion with non-indigenous model in the same treatment in PTSD on women (Persian)]. Knowledge and Research in Applied Psychology. 2021; 22(1):30-42. [Link]
34. Sobhani Tabar Sh, Hamidi F, Tahmasabipour N. [Effectiveness of psychodrama in reducing the psychological nervous problems of students with post-traumatic stress disorder (Persian)]. Neuropsychology. 2020; 6(20):121-46. [Link]
35. Baharvand V, Dortaj F, Nasri S, Nasrollahi B. [Comparison of the effectiveness of cognitive behavioral therapy with cognitive hypnotherapy and eye movement desensitization (EMDR) and reprocessing on the reduction of traumatic stress symptoms of flooded women (Persian)]. Journal of Psychological Science. 2020; 19(86):203-12. [Link]
36. No Authors. Psychometric properties of the Posttraumatic Diagnostic Scale for DSM-5 (PDS-5): Correction to Foa et al. (2015). Psychological Assessment. 2016; 28(10):1165. [DOI:10.1037/pas0000360] [PMID]
37. Panahi A. [Normative test of Durham Andre Ray (card A) on middle school male students in Tehran (Persian)] [MA Thesis].Roudhan:  Islamic Azad University; 2003. [Unpublised]
38. Jafari Z, Steffen Moritz Ph, Zandi T, Akbari Kamrani AA, Malayeri S. [Iranian version of the Rey Auditory Verbal Learning Test: A validation study (Persian)]. Payesh. 2010; 9(3):307-16. [Link]
39. Kapur, N. Neuropsychological Assessment, Fourth Edition. Journal of Neurology. 2005; 252:1290-1 [Link]
40. Kapoula Z, Lê TT, Bonnet A, Bourtoire P, Demule E, Fauvel C, et al. Poor Stroop performances in 15-year-old dyslexic teenagers. Experimental Brain Research. 2010; 203(2):419-25. [DOI:10.1007/s00221-010-2247-x] [PMID]
41. Shahqalian M, Azad Falah P, Fathi Ashtiani A, Khodadadi M. [Designing a software version of the Wisconsin Card Sorting Test (WCST): Theoretical foundations, construction method and psychometric properties (Persian)]. Clinical Psychology Studies. 2019; 1(4):110-34. [Link]
42. Salehabadi R, Roshanfekr M, Salehi Kian N, Salehi Kian H, Vejdani M, Yarelahi M. [Post-Traumatic stress disorder among covid-19 survivors at 1-month follow-up after Vasei Hospital of Sabzevar Discharge in 2019: A short report (Persian)]. Journal of Rafsanjan University of Medical Sciences. 2022; 21(6):687-96 [DOI:10.52547/jrums.21.6.687]
43. Posner MI. The psychology of attention. In: Gazzaniga MS, Blakemore C, editors.  Handbook of psychology. New York: Academic Press; 1975.
44. Davies DR, Jones DM, Taylor A. Selective and sustainedattention tasks: Individual and group differences. In: Parasuraman R, Davies DR, editors.  Varieties of attention. Orlando: Academic; 1984.
45. Posner MI, Boies SJ. Components of attention. Psychological Review. 1971; 78(5):391-408. [DOI:10.1037/h0031333]
46. Kinchla RA. Attention. Annual Review of Psychology. 1992; 43:711-42. [DOI:10.1146/annurev.ps.43.020192.003431] [PMID]
47. Miller EK, Cohen JD. An integrative theory of prefrontal cortex function. Annual Review of Neuroscience. 2001; 24:167-202. [DOI:10.1146/annurev.neuro.24.1.167] [PMID]
48. Oraki M, Faraji R, Zare H, Nejati V. [The effectiveness of transcranial brain stimulation using direct electric current (TDCS) on the executive functions of war survivors suffering from post-traumatic stress disorder (PTSD) (Persian)]. Neuropsychology. 2016; 3(11):103-14. [Link]