Citation Nr: 21040505 Decision Date: 07/05/21 Archive Date: 07/05/21 DOCKET NO. 17-17 145 DATE: July 5, 2021 ORDER Service connection for osteoarthritis and meniscal tear of the right knee is granted. Service connection for osteoarthritis and meniscal tear of the left knee is granted. Service connection for obstructive sleep apnea is granted. Service connection for herpes zoster virus (shingles) is denied. Service connection for hypertension is granted. Service connection for chronic obstructive pulmonary disease (COPD) is denied. REMANDED Entitlement to total disability rating based on individual unemployability due to service-connected disabilities (TDIU) is remanded. FINDINGS OF FACT 1. The Veteran manifested chronic right knee pain after sustaining in-service injuries with continued symptomatology to the present and development of osteoarthritis and meniscal tear of the right knee with related disability. 2. The Veteran manifested chronic left knee pain after sustaining in-service injuries with continued symptomatology to the present and development of osteoarthritis and meniscal tear of the left knee with related disability. 3. The evidence is in relative equipoise as to whether the Veteran's obstructive sleep apnea is proximately due to his service-connected posttraumatic stress disorder (PTSD). 4. The preponderance of the evidence is against finding that infection with herpes zoster virus (shingles) began during active service or is otherwise related to an in-service injury or disease, including exposure to herbicide agents. 5. The evidence is in relative equipoise as to whether the Veteran's hypertension is proximately due to his service-connected obstructive sleep apnea. 6. The preponderance of the evidence is against finding that the Veteran's COPD is secondary to service-connected PTSD or obstructive sleep apnea or that it is otherwise related to an in-service injury or disease, including exposure to herbicide agents. CONCLUSIONS OF LAW 1. The criteria for service connection for osteoarthritis and meniscal tear of the right knee are met. 38 U.S.C. §§ 1110, 1111, 1112, 1113, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.309(a). 2. The criteria for service connection for osteoarthritis and meniscal tear of the left knee are met. 38 U.S.C. §§ 1110, 1111, 1112, 1113, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.309(a). 3. The criteria for service connection for obstructive sleep apnea as secondary to service-connected PTSD are met. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.310. 4. The criteria for service connection for herpes zoster virus (shingles), including as due to exposure to herbicide agents, are not met. 38 U.S.C. §§ 1110, 1116, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.307, 3.309(e). 5. The criteria for service connection for hypertension as secondary to service-connected obstructive sleep apnea are met. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.310. 6. The criteria for service connection for COPD, to include as due to exposure to herbicide agents or as secondary to service-connected PTSD or obstructive sleep apnea, are not met. 38 U.S.C. §§ 1110, 1116, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.307, 3.309(e), 3.310. REASONS AND BASES FOR FINDINGS AND CONCLUSIONS The Veteran served on active duty from October 1966 to October 1968. These matters come before the Board of Veterans' Appeals (Board) on appeal from August 2014 and August 2015 rating decisions. A Board hearing was held in January 2020, and a transcript is of record. In May 2020, the Board remanded these issues for further development, and the case has been returned for appellate consideration. The Board notes that new evidence has been associated with the Veteran's claims file since the January 2021 supplemental statement of the case. Generally, the Board may not consider evidence not previously reviewed by the Agency of Original Jurisdiction (AOJ) unless a waiver of initial AOJ review is obtained from the veteran. 38 C.F.R. § 20.1305(c); Disabled Am. Veterans v. Sec'y of Veterans Aff., 327 F.3d 1339 (Fed. Cir. 2003). However, if a veteran filed a substantive appeal on or after February 2, 2013, as occurred here, an automatic waiver of initial AOJ review is implied for new evidence submitted by the appellant or representative to the AOJ or the Board. 38 U.S.C. § 7105(e). Because the Veteran filed his substantive appeal after February 2, 2013, and he has not specifically requested initial AOJ consideration of the evidence, such waiver is presumed. Service Connection Service connection may be granted for disability resulting from disease or injury incurred in or aggravated by active service. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. § 3.303. The three-element test for service connection requires evidence of: (1) a current disability; (2) in-service incurrence or aggravation of a disease or injury; and (3) a causal relationship between the current disability and the in-service disease or injury. Shedden v. Principi, 381 F.3d 1163, 1166 -67 (Fed. Cir. 2004). For chronic diseases listed under 38 C.F.R. § 3.309(a), including arthritis, the second and third elements of service connection may be established by demonstrating (1) that a condition was "noted" during service; (2) post-service continuity of symptoms; and (3) medical or, in certain circumstances, lay evidence of a link between the present disability and the continuity of symptoms. 38 C.F.R. § 3.303(b); see Walker v. Shinseki, 708 F.3d 1331, 1338 (Fed. Cir. 2013) (constraining § 3.303(b) to those chronic diseases listed in § 3.309(a)); Jandreau v. Nicholson, 492 F.3d 1372, 1377 (Fed. Cir. 2007) (stating that whether lay evidence is competent and sufficient in a particular case is a factual issue to be addressed by the Board). Alternatively, a disability may be service connected on a secondary basis if it is proximately due to or the result of a service-connected disease or injury; or, if it is aggravated beyond its natural progression by a service-connected disease or injury. 38 U.S.C. § 1110; 38 C.F.R. § 3.310(a), (b). To establish service connection for a claimed disability on a secondary basis, there must be (1) medical evidence of a current disability; (2) a service-connected disability; and (3) medical evidence of a nexus between the service-connected disease or injury and the current disability. See Wallin v. West, 11 Vet. App. 509, 512 (1998). Aggravation need not be permanent, and objective measurement or numerical quantification is not required to ascertain an increase in disability. Ward v. Wilkie, 31 Vet. App. 233 (2019). For those who had active service in the Republic of Vietnam between January 9, 1962, and May 7, 1975, service connection for certain enumerated diseases may be based upon presumed exposure to an herbicide agent, such as Agent Orange. 38 U.S.C. § 1116; 38 C.F.R. §§ 3.307(a)(6)(iii), 3.309(e). 1. Right Knee 2. Left Knee The Veteran seeks service connection for disabilities of the right and left knees, including osteoarthritis and meniscal tears, contending that they are the result of injuries sustained during a helicopter crash. He has reported that bilateral knee pain began in service after the helicopter crash and progressively got worse over the years. See Statement, received 9/20/1978; Hearing Transcript, received 1/28/2020; C&P Exam, received 1/19/2021. The Board concludes that the criteria for service connection for osteoarthritis and meniscal tears of the right and left knees are met. 38 U.S.C. §§ 1110, 1111, 1112, 1113, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.309; Shedden v. Principi, 381 F.3d 1163, 1166 -67 (Fed. Cir. 2004); Walker v. Shinseki, 708 F.3d 1331, 1338 (Fed. Cir. 2013) (constraining § 3.303(b) to those chronic diseases listed in § 3.309(a)). The Board finds that the first Shedden element is met because the Veteran has been found to currently have osteoarthritis and meniscal tears of the right and left knees. See C&P Exam, received 1/19/2021. The Board also finds that the second Shedden element is met because the nature of the Veteran's service was consistent with combat and with having been in a helicopter crash. The Veteran's DD Form 214 shows that he was in receipt of the Vietnam Campaign Medal. His military personnel records show that he served in Vietnam from December 24, 1967, to September 30, 1968, and his principal duty was gunner. He participated in Vietnam Counter Offensive Phase III, and he was in receipt of the Bronze Star Medal. See STR, received 4/2/1969; Military Personnel Record, received 9/20/1978. An April 1968 narrative summary from the USS Sanctuary, a naval hospital, states that the Veteran was admitted after having been in a helicopter crash in which he suffered a broken nose, broken teeth, and laceration of the lower lip. "There was also a bruise on the left knee area." Left thigh films were recorded as normal. His injuries were noted as line of duty, not due to own misconduct. The Veteran presented a statement of a fellow helicopter crewman as to the occurrence of the helicopter crash in April 1968. See Statement, received 9/20/1978. During his hearing, the Veteran stated that currently his knees were painful. He reported that, during service in April 1968, he injured his knees during a helicopter crash at a landing zone in the A Shau Valley. He stated that the landing was in the dark and fog, and the landing zone was on a hilltop. He remembered that he heard an explosion, saw a flash, and saw the blades go flying. The helicopter crashed, and the Veteran did not remember how he got back to the landing zone or to his unit. He stated that he was medevaced out for face injuries, but he did not remember it. The Board turns its attention to nexus. The Veteran testified that he saw a doctor for his knees once in approximately 1974, "right after" he got married. He did not remember the outcome. He stated that he always had problems with painful knees, which he ignored until approximately 2013. He reported that he was found to have bilateral meniscus tears. A VA examining clinician opined that it was less likely than not that the Veteran's right and left knee osteoarthritis was related to in-service injuries related to the helicopter crash. It was opined that it was more likely that the Veteran's current pain was related to bilateral meniscus tears that occurred in 2013 and that there were multiple other "aging/occupational daily activity factors in the intervening years." See C&P Exam, received 1/19/2021. In formulating the rationale to support the negative nexus opinion, the clinician essentially relied solely upon the lack of in-service treatment records for knee injuries. In a private medical opinion, it was stated that it is well documented in the medical literature that prior injuries increase the likelihood of developing joint arthritis and that the manifestation can occur many years after the inciting injury. It was stated that it was "increasingly believed that that the [osteoarthritis] development in the injured joints initiates during the initial traumatic event by intra-articular pathogenic processes, such as apoptosis of articular chondrocytes, subchondral bone remodelling, cellular infiltration and the release of inflammatory mediators in synovial fluid." It was opined that it was as likely as not that the Veteran's knee injuries from the in-service helicopter crash contributed to the degenerative joint disease, osteoarthritis, and chondromalacia patella discovered in 2013." It was explained that underlying post-traumatic changes to the Veteran's knees predisposed him to the meniscal tears that occurred in 2013. See Medical Treatment Record, received 5/27/2021. The Board has the responsibility of weighing conflicting medical opinions and may place greater weight on one physician's opinion over another depending upon factors such as reasoning employed by the physicians and the extent to which they reviewed prior clinical records and other evidence. See Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 30004 (2008); Prejean v. West, 13 Vet. App. 444, 44849 (2000) (stating that factors for assessing the probative value of a medical opinion include the thoroughness and detail of the opinion). The Board finds the VA medical opinion problematic, and therefore, less probative than the private medical opinion. The VA clinician relied solely upon the lack of in-service medical records to opine negatively. As a combat veteran for the purpose of his service connection claims for bilateral knee disability, the Veteran's statements are sufficient to establish the occurrence of bilateral knee injuries during the helicopter crash and ongoing knee pain. See 38 U.S.C. § 1154(b); 38 C.F.R. § 3.304(d); VAOPGCPREC 12-99, 65 Fed. Reg. 6256, 6257 (Feb. 8, 2000) (addressing the phrase "engaged in combat with the enemy"). The private medical opinion, on the other hand, provided a medical explanation of how the Veteran's in-service bilateral knee injuries could set the stage for later bilateral osteoarthritis of the knees. The opinion further explained how the presence of osteoarthritis could in turn predispose the Veteran to the bilateral meniscus tears he experienced in 2013. That being the case, the Board finds the private medical opinion highly probative. Consequently, the third Shedden element is met, and service connection for osteoarthritis and meniscal tears of the right and left knees is warranted. 3. Obstructive Sleep Apnea The Veteran seeks service connection for obstructive sleep apnea, to include as secondary to service-connected PTSD. The Board concludes that the criteria for service connection for obstructive sleep apnea as secondary to service-connected PTSD are met. 38 U.S.C. §§ 1110, 1131, 5107; 38 C.F.R. §§ 3.102, 3.310; Wallin v. West, 11 Vet. App. 509, 512 (1998). After an October 2014 sleep study, the Veteran was found to have severe obstructive sleep apnea. See C&P Exam, received 1/19/2021. The Veteran is service-connected for PTSD, effective June 11, 2009. See Rating Decision, received 9/14/2010. Consequently, the first and second Wallin elements are met. The Board will turn its attention to nexus. The Veteran has stated that the earliest he was told that he snored was in the 1970s. He did not remember sleeping while in service, but when hunting, his buddies told him that he snored, and his wife told him he snored. See Hearing Transcript, received 1/28/2020. The Board has found previously that a July 2015 VA medical opinion was inadequate, and consequently, it is not probative. See May 2020 Board Remand; VHA Clarification, received 7/30/2015. In November 2020, a VA examining clinician opined that it was less likely than not that the Veteran's sleep apnea was directly related to service because the condition was not diagnosed until 46 years after active duty. It was also opined that it was less likely than not that his sleep apnea was due to his service-connected PTSD. It was stated that "[t]here is insufficient medical literature to support a nexus." It was concluded that the Veteran had significant risk factors, including age, gender, chronic obesity, and craniofacial/upper airway soft tissue abnormalities for developing obstructive sleep apnea. Citing to information found at Mayo Clinic's website, the clinician discussed only the anatomical/mechanical occlusion of the airway as causing obstructive sleep apnea. See C&P Exam, received 1/19/2021. In a private medical opinion, it was stated that there are causal links demonstrated between obstructive sleep apnea and PTSD. It was explained that in addition to the traditional pathophysiologic explanation for obstructive sleep apnea, newer research and observational studies have demonstrated that the etiology of sleep apnea is much more complex. Significantly, it was explained that it had been postulated for years that there was a bidirectional relationship between obstructive sleep apnea and PTSD since sleep disruption secondary to sleep apnea exacerbates PTSD symptoms, and hyperarousal and sympathetic activation from PTSD predisposes upper airway collapse. It was stated that, furthermore, treatment of sleep apnea with CPAP had been shown to improve symptoms of PTSD. Numerous literature citations with in-depth discussion addressing the relationship between sleep apnea and PTSD were provided. It was concluded that it was as likely as not that the Veteran's obstructive sleep apnea was caused by his service-connected PTSD. See Medical Treatment Record, received 5/27/2021. Weighing the conflicting medical opinions, the Board finds that the evidence is in relative equipoise as to whether the Veteran's obstructive sleep apnea is caused by his service-connected PTSD. See Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 30004 (2008); Prejean v. West, 13 Vet. App. 444, 44849 (2000). The VA clinician cited to research and known risk factors as to why the Veteran was at risk for anatomical collapse of the airway, focusing on the Veteran's recent medical history. The Board notes, however, that the Veteran's stressor event was an in-service helicopter crash in which he was injured, and soon after service he weighed 155 pounds. See VA Examination, received 4/8/1969; Statement, received 9/20/1978. The Veteran is competent to report his symptoms of sleep apnea and their onset. See 38 C.F.R. § 3.159(a)(2) (defining competent lay evidence); Charles v. Principi, 16 Vet. App. 370 (2002) (finding the veteran competent to testify to symptomatology capable of lay observation). He has reported credibly that as early as the 1970s his hunting buddies and his wife told him that he snored. The facts of this case seem to undercut the posited risk factors of age and chronic obesity as cited by the VA clinician as contributing to his development of sleep apnea. In the VA medical opinion, the notion of a causative relationship between PTSD and sleep apnea was dismissed as not supported by the medical literature. The private medical opinion, on the other hand, cited numerous sources showing comorbidity between PTSD and sleep apnea, and explained that research has shown a bidirectional relationship between the two conditions. In the context of the early onset of symptoms after service in this case, namely snoring, a bidirectional relationship between the two conditions seems to apply. Therefore, the Board finds that the opposing medical opinions are in relative equipoise, and accordingly, the third Wallin element is met. That being the case, service connection for obstructive sleep apnea as secondary to service-connected PTSD is warranted. 4. Herpes Zoster Virus (shingles) The Veteran seeks service connection for shingles caused by herpes zoster virus, contending that it may be related to in-service exposure to herbicide agents. See Correspondence, received 12/23/2014; 4/6/2015; Hearing Transcript, received 1/28/2020. The Board concludes that the criteria for service connection for herpes zoster virus (shingles), to include as due to exposure to herbicide agents, are not met. See 38 U.S.C. §§ 1110, 1116, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.307, 3.309(e); Shedden v. Principi, 381 F.3d 1163, 1166 -67 (Fed. Cir. 2004). The first Shedden element is met because, during a VA examination, the Veteran was found to have a history of herpes zoster virus (shingles), diagnosed in 2017, which was quiescent. See C&P Exam, received 1/19/2021. The Veteran's service treatment records are silent for any complaints, symptoms, diagnosis, or treatment related to herpes zoster virus, such as chicken pox or shingles, and he does not contend otherwise. As stated above, the Veteran is a combat veteran of the Vietnam War Era such that he is presumed to have been exposed to herbicide agents, and accordingly, the second Shedden element is met. See 38 U.S.C. § 1116; 38 C.F.R. §§ 3.07(a)(6)(iii), 3.309(e). The Board turns its attention to nexus. During his hearing, the Veteran stated that his symptoms of shingles started four years before and that he had had ongoing treatment as recently as the week before. He stated that he did not know whether there was a relationship between exposure to herbicide agents and his infection by herpes zoster virus. See Hearing Transcript, received received 1/28/2020. The Veteran's attorney has contended that "[a]lthough herpes zoster virus is not included on the presumptive list of diseases for Agent Orange exposure, this does not mean that the claimant did not develop this disability because of it." It was noted that exposure to herbicide agents has been linked to "different skin conditions" and that the Veteran's "herpes zoster virus could have been caused by the direct exposure." See Third Party Correspondence, received 3/29/2021. The examining VA clinician opined that it was less likely than not that the Veteran's herpes zoster virus infection was related to service because his service treatment records were silent for any symptoms related to chicken pox and the Veteran developed shingles in 2013. It was stated that herpes zoster virus (shingles) is not a condition listed as being related to exposure to herbicide agents. As factfinder, the Board has the responsibility to determine the credibility and weight to be given to the evidence. See Washington v. Nicholson, 19 Vet. App. 362, 367-68 (2005). The Board notes that the Veteran, while entirely competent to report his symptoms, is not competent to proffer an opinion as to diagnosis or etiology. See 38 C.F.R. § 3.159(a)(1)(2) (defining competent medical evidence and competent lay evidence); Charles v. Principi, 16 Vet. App. 370 (2002) (finding the veteran competent to testify to symptomatology capable of lay observation); Barr v. Nicholson, 21 Vet. App. 303, 307 (2007) (stating that "lay persons are not competent to opine on medical etiology or render medical opinions."). Such opinions require specific medical training and are beyond the competency of a lay person, and accordingly, the Board finds the medical findings more probative. See Jandreau v. Nicholson, 492 F.3d 1372, 137677 (Fed. Cir. 2007). The claimant bears the burden of presenting and supporting a claim for benefits. 38 U.S.C. § 5107(a); Fagan v. Shinseki, 573 F.3d 1282, 128688 (Fed. Cir. 2009). Here, the Veteran has failed to provide any factual support for his claim that he was infected with herpes zoster virus during active duty service or any scientific support for the proposition that exposure to herbicide agents would predispose him to infection with herpes zoster virus. The conditions affecting the skin that have been found to be presumptively associated with exposure to herbicide agents are not conditions mediated by viral infections. See 38 C.F.R. § 3.309(e). Consequently, the Board finds the negative VA medical opinion the most probative evidence as to nexus, and accordingly, the third Shedden element is not met. Based upon the foregoing, as the preponderance of the evidence is against the claim, the benefit of the doubt rule does not apply, and the claim for service connection for herpes zoster virus (shingles) must be denied. See 38 U.S.C. §§ 501, 5107(b); 38 C.F.R. §§ 3.102, 4.3, 4.7; see also Gilbert v. Derwinski, 1 Vet. App. 49, 54 (1990). 5. Hypertension The Veteran seeks service connection for hypertension as due to exposure to herbicide agents or as secondary to his service-connected PTSD or to obstructive sleep apnea. The Board concludes that the criteria for service connection for hypertension as secondary to service-connected obstructive sleep apnea are met. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.310; Wallin v. West, 11 Vet. App. 509, 512 (1998). The Veteran has been found to have hypertension for which he receives treatment. See C&P Exam, received 1/19/2021. Herein, the Board has granted service connection for obstructive sleep apnea. Consequently, the first and second Wallin elements are met. The Board will turn its attention to nexus. The examining VA clinician opined that it was less likely than not that the Veteran's hypertension was directly related to service, including exposure to herbicide agents, or as secondary to any of his other disabilities. Rather, it was opined that his hypertension was due to his smoking history because, according to MayoClinic.org, there is "extensive medical literature to link hypertension to smoking." See C&P Exam, received 1/19/2021. In a private medical opinion, it was opined that the Veteran's hypertension should be service-connected as it is related to the Veteran's obstructive sleep apnea. It was stated that current thinking is that obstructive sleep apnea represents the most prevalent secondary contributor to hypertension. The pathophysiology has been summarized as obstructive sleep apnea induces intermittent hypoxemia thereby causing oxidative stress and leading to dysfunction of vascular endothelium. Additionally, excessive outflow of sympathetic vasoconstrictor together with diminished nitric oxide bioavailability plays a role in elevation of blood pressure. Last, episodes of obstructive sleep apnea up-regulate sympathetic excitation, which acts on the chemoreflex and may consequently result in hypertension. As factfinder, the Board has the responsibility to determine the credibility and weight to be given to the evidence. See Washington v. Nicholson, 19 Vet. App. 362, 367-68 (2005). Here, the record consists of two distinct medical theories as to what is at least as likely as not the cause of the Veteran's hypertension. The VA clinician has presented the Veteran's smoking history, which is a traditionally recognized cause of hypertension. The private medical opinion relies upon current research that is showing the pathophysiological impacts of untreated obstructive sleep apnea, which includes hypertension. The opinion lays out the current thinking as to the physiological mechanisms that make untreated obstructive sleep apnea dangerous due to resulting hypertension. Because the Veteran has a history of smoking and a history of untreated obstructive sleep apnea, these theories of causation apply equally thereby putting the medical evidence in equipoise as to the cause of the Veteran's hypertension. That being the case, the third Wallin element is met, and accordingly, service connection for hypertension as secondary to service-connected obstructive sleep apnea is warranted. 6. COPD The Veteran seeks service connection for COPD, contending that it is due to in-service exposure to herbicide agents or as secondary to service-connected PTSD or obstructive sleep apnea. The Board concludes that the criteria for service connection for COPD, to include as due to exposure to herbicide agents or as secondary to service-connected PTSD or obstructive sleep apnea, are not met. 38 U.S.C. §§ 1110, 1116, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.307, 3.309(e), 3.310; Shedden v. Principi, 381 F.3d 1163, 1166 -67 (Fed. Cir. 2004); Wallin v. West, 11 Vet. App. 509, 512 (1998). The Veteran has been found to have COPD and is treated for same. See C&P Exam, received 1/19/2021. Therefore, the first Shedden and Wallin elements are met. The Veteran is service-connected for PTSD, and the Board has granted service connection for obstructive sleep apnea herein. Accordingly, the second Wallin element is met. The Board will turn its attention to the Veteran's contention that his COPD is secondary to his service-connected PTSD. In a July 2015 VA medical opinion, it was opined that the Veteran's COPD was less likely than not proximately due to or the result of his service-connected PTSD. It was stated that a review of medical literature did not support a contention of COPD being caused by PTSD. It was opined that the Veteran's COPD was more likely due to his 40-year history of cigarette smoking, having quit in 2009. It was also opined that "there is no documentation of aggravation of his COPD beyond the natural progression." See VHA Clarification, received 7/30/2015. This opinion was reiterated in a November 2020 VA examination. See C&P Exam, received 1/19/2021. In a private medical opinion, it was stated that the Veteran's "40 pack-year smoking history unequivocally contributed to his development of severe COPD." The opinion went on to cite to numerous articles addressing the higher incidence of smoking in the population of individuals with PTSD. It was stated that in addition to the higher incidence of smoking in that population, the individuals had a harder time quitting. It was opined that the Veteran's successful cessation of smoking in 2008/2009 coincided with his engagement in formal PTSD treatment in 2007, "further underscoring this relationship." It was opined that, "[i]n this case, the demonstrated causal relationship between PTSD and smoking proves that [the Veteran's] PTSD contributed to his heavy tobacco use that resulted in severe COPD." See Medical Treatment Record, received 5/27/2021; see also Medical Treatment Record, received 6/2/2020 (articles from Veteran). The claimant bears the burden of presenting and supporting a claim for benefits. 38 U.S.C. § 5107(a); Fagan v. Shinseki, 573 F.3d 1282, 128688 (Fed. Cir. 2009). In making determinations, VA is responsible for ascertaining whether the evidence supports the claim or is in relative equipoise, with the veteran prevailing in either event, or whether the preponderance of the evidence is against the claim, in which case the claim is denied. See 38 U.S.C. § 5107; 38 C.F.R. § 3.102; Gilbert v. Derwinski, 1 Vet. App. 49, 54 (1990). As factfinder, the Board has the responsibility to determine the credibility and weight to be given to the evidence. See Washington v. Nicholson, 19 Vet. App. 362, 367-68 (2005). The Board finds that the preponderance of the evidence is against finding that the Veteran's smoking habit was related to his PTSD, and therefore, the contention that his COPD is related to his PTSD fails. VA medical records show that the Veteran had a 40-year history of cigarette smoking, quitting in 2008/2009. The evidence of record, however, does not establish whether the Veteran began smoking during active duty service or afterward. During psychiatric consultation in June 2009 it was recorded that the Veteran had probably met the diagnostic criteria for PTSD while still in Vietnam and for the first few months after returning home. His symptoms resolved thereafter until September 11, 2001. See CAPRI, received 7/26/2015. The evidence of record establishes that for the majority of the years that the Veteran smoked, he was asymptomatic for PTSD. The Veteran has presented no evidence that his smoking was a method of self-treating symptoms of PTSD. The Board will now turn its attention to the Veteran's contention that his COPD is secondary to his obstructive sleep apnea. In the July 2015 VA medical opinion, it was opined that it was less likely than not that the Veteran's COPD was related to his obstructive sleep apnea because his diagnosis of COPD pre-dated the diagnosis of sleep apnea and a review of medical literature did not support a contention of COPD being caused by sleep apnea. It was opined that the Veteran's COPD was more likely due to his 40-year history of cigarette smoking and that there was no documentation of aggravation of his COPD beyond its natural progression. This opinion was reiterated in the January 2021 VA medical opinion. In elaboration, the VA clinician explained that COPD refers to a group of lung diseases that cause airflow blockage and breathing-related problems. It was stated that, in the United States, tobacco smoke is a key factor in the development and progression of COPD. On the other hand, it was explained, obstructive sleep apnea is the narrowing of airways leading to the lungs during sleep. It was noted that the medical literature recognizes that these two common conditions may co-exist, which "is the result of chance alone." It was concluded that there was no concrete evidence to support a nexus between the Veteran's COPD and obstructive sleep apnea. The Veteran has presented no scientific evidence in support of this contention, and therefore, the Board finds that the preponderance of the evidence is against finding that his COPD is related to his obstructive sleep apnea. Consequently, the third Wallin element is not met, and the Veteran's claim fails as to a secondary basis for service connection. The Veteran has stated that he related his COPD to service due to exposure to herbicide agents. As stated above, the Veteran is a combat veteran of the Vietnam War Era such that he is presumed to have been exposed to herbicide agents, and accordingly, the second Shedden element is met as to that contention. See 38 U.S.C. § 1116; 38 C.F.R. §§ 3.07(a)(6)(iii), 3.309(e). The Veteran's service treatment records are silent for any symptoms, complaints, diagnosis, or treatment related to COPD, and the Veteran does not contend otherwise. He has stated that he believed, given time, it will be shown that herbicide agents in Vietnam affected lungs more than just by cancer. He has stated that his doctor, Dr. L.S., told him that his COPD could have been caused by Agent Orange or it could have been caused by smoking. See Hearing Transcript, received 1/28/2020. The November 2020 VA clinician opined that it was less likely than not that the Veteran's COPD was related to service because he had a 40-year history of smoking and his COPD was diagnosed 46 years after service. It was explained that the cause of COPD usually is "long-term exposure to irritants that damage lungs and airways," which in the United States is commonly caused by cigarette smoking. The clinician also stated that, according to PublicHealth.VA.gov, COPD is not a disease associated with exposure to herbicide agents. Because medical opinions as to etiology of COPD require specific medical training and are beyond the competency of a lay person, the Board finds the medical findings here more probative. See Jandreau v. Nicholson, 492 F.3d 1372, 137677 (Fed. Cir. 2007); see also 38 C.F.R. §§ 4.40, 4.45, 4.59 (2017); DeLuca v. Brown, 8 Vet. App. 202 (1995); Prejean v. West, 13 Vet. App. 444, 4489 (2000). The Board finds that the preponderance of the evidence weighs against finding any other cause for the Veteran's COPD other than his history of smoking. Indeed, his private medical opinion asserted as much. The only assertion that the Veteran has made that his COPD is directly related to service is his belief that COPD should be found related to exposure to herbicide agents, not that it has been found to be so. He has not presented any scientific evidence to support his belief. Although the Veteran has credibly reported that his physician told him that his COPD may have been related to exposure to herbicide agents, there is no scientific evidence to support that contention. Consequently, the third Shedden element is not met, and the claim fails on a direct basis. Based upon the foregoing, as the preponderance of the evidence is against the claim, the benefit of the doubt rule does not apply, and the claim for service connection for COPD, to include as due to exposure to herbicide agents or as secondary to service-connected PTSD or obstructive sleep apnea, must be denied. See 38 U.S.C. §§ 501, 5107(b); 38 C.F.R. §§ 3.102, 4.3, 4.7; see also Gilbert v. Derwinski, 1 Vet. App. 49, 54 (1990). REASONS FOR REMAND Entitlement to TDIU is inextricably intertwined with the evaluations of the disabilities for which service connection has been granted herein. See Harris v. Derwinski, 1 Vet. App. 180, 183 (1991) (finding two issues are "inextricably intertwined" when they are so closely tied together that a final decision on one issue cannot be rendered until a decision on the other issue has been rendered). Furthermore, in the appellate brief, the Veteran's attorney has requested remand so that a VA specialist's opinion can be obtained as to the Veteran's ability to secure or follow a substantially gainful occupation. See Third Party Correspondence, received 3/29/2021. Consequently, a remand is required to obtain a specialist's opinion and readjudication of the issue on appeal. This matter is REMANDED for the following actions: 1. Refer the Veteran's claims file and a copy of this Remand to an appropriately qualified specialist to help ascertain the effect the Veteran's service-connected disabilities had on performing work during the period on appeal. The specialist should provide an opinion as to the Veteran's occupational impairments and limitations resulting from all his service-connected disabilities. In rendering the opinion, the specialist should consider the Veteran's education, special training, and previous work experience, but should not consider age or the effect of any non-service-connected disabilities. A rationale should be given for all opinions and conclusions rendered. 2. Readjudicate the claim. L. CHU Veterans Law Judge Board of Veterans' Appeals Attorney for the Board Leanne M. Innet, Counsel The Board's decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.