SLEEP APNEA SYNDROMES (OBSTRUCTIVE CENTRAL MIXED)

Summary

The veteran, who served from December 1964 to December 1967, appeals the denial of service connection for obstructive sleep apnea (OSA) and the remand of his claim for headaches. The Board denied service connection for OSA, noting that it was not shown in service and was not causally or etiologically related to service. The veteran's service treatment records did not reflect complaints or diagnosis of OSA, and the separation examination did not identify symptoms reasonably attributable to OSA. While the VA conceded toxic exposure, a VA examiner opined that OSA was less likely than not caused by these exposures, citing a lack of medical evidence supporting a link and noting outside risk factors like obesity and a deviated septum. The veteran argued OSA was secondary to service-connected diabetes mellitus (DM), supported by a private consultant's opinion suggesting a bidirectional relationship. However, the Board afforded this opinion lesser probative value, finding its reliance on general associations and speculative language insufficient to establish causation. The Board also rejected the argument that DM caused obesity, which then led to OSA, finding the Veteran's weight management efforts and exercise routine did not indicate inability to control weight due to service-connected disabilities. The Board found the private consultant's conclusions unsupported by the record and the medical evidence weighed against the claim. The Board noted no VA opinion was obtained for secondary OSA, but a remand was not required as the private opinion was submitted after the AOJ decision. The Board also considered the Veteran's lay statements regarding OSA but found them less probative than the VA examination. The Board remanded the headache claim, noting the service treatment records and separation examination showed in-service complaints of headaches and dizziness, but no direct service connection opinion was obtained.

Rationale

No in-service incurrence of OSA; VA examiner found no medical evidence linking OSA to toxic exposures; Private consultant's opinion lacked probative value due to speculative reasoning and reliance on associations

Full Decision Text

Citation Nr: A26034116
Decision Date: 04/14/26	Archive Date: 04/14/26

DOCKET NO. 250909-584775
DATE: April 14, 2026

ORDER

Service connection for obstructive sleep apnea (OSA) is denied.

REMANDED

Service connection for a headache disorder.

FINDINGS OF FACT

1. The Veteran served on active duty from December 1964 to December 1967. 

2. OSA was not shown in service, is not causally or etiologically related to service, and was not caused by or permanently worsened in severity by a service-connected disability.

CONCLUSION OF LAW

OSA was not incurred in service and is not proximately due to, aggravated by, or the result of a service-connected disability. 38 U.S.C. §§ 1110, 5103(a), 5103A, 5107 (2012); 38 C.F.R. §§ 3.159, 3.303, 3.310 (2025).

REASONS AND BASES FOR FINDINGS AND CONCLUSION

This decision has been written under the guidelines of the Veterans Appeals Improvement and Modernization Act, also known as the Appeals Modernization Act (AMA). In July 2025, the agency of original jurisdiction (AOJ) denied the claim. In October 2025, the Veteran appealed to the Board via a Form 10182 and elected the Hearing docket. In November 2025, he withdrew the hearing request. 

Therefore, the Board may only consider the evidence of record at the time of the July 2025 decision on appeal, as well as any evidence submitted by the Veteran within 90 days following receipt of the withdrawal of the hearing request in November 2025. 38 C.F.R. § 20.302(b). 

Turning to the relevant laws and regulations, service connection may be granted on a direct basis as a result of disease or injury incurred in service based on nexus using a three-element test: (1) the existence of a present disability; (2) in-service incurrence or aggravation of a disease or injury; and (3) a causal relationship between the present disability and the disease or injury incurred in or aggravated by service. See 38 C.F.R. §§ 3.303(a), (d); Holton v. Shinseki, 557 F.3d 1363, 1366 (Fed. Cir. 2009). 

Service connection may be granted on a secondary basis for a disability which is aggravated by, proximately due to, or the result of a service-connected disease or injury under 38 C.F.R. § 3.310.  Allen v. Brown, 7 Vet. App. 439 (1995). In order to establish service connection on a secondary basis, there must be (1) evidence of a current disability; (2) evidence of a service-connected disability; and (3) medical evidence establishing a link between the service-connected disability and the current disability. See Wallin v. West, 11 Vet. App. 509, 512 (1998).

Service connection may be granted on a secondary basis with an intercurrent cause of obesity if a service-connected disability caused or aggravated a veteran's obesity, and the aggravation of obesity was then a substantial factor in causing or aggravating the claimed disorder, and whether the claimed disorder would have occurred but for obesity aggravated by the service-connected disability. See Walsh v. Wilkie, 32 Vet. App, 300, 307 (2020). 

Turning to the medical evidence, a diagnosis of OSA was first shown following a June 2025 sleep study. As such, a disorder is shown and the first element of service connection is met. 

Next, as to in-service incurrence, the service treatment records (STRs) do not reflect complaints of, treatment for, or a diagnosis of OSA. During the November 1967 separation, the Veteran specifically denied a history of frequent trouble sleeping. Further, while the examining physician noted a history of headaches and dizzy spells, he did not identify any symptom or diagnoses reasonably attributable to OSA, such as snoring or daytime fatigue. 

Moreover, the Veteran does not contend that OSA began during service. As such, the medical evidence does not support the in-service incurrence of OSA. Therefore, the medical evidence does not support service connection for OSA on a direct basis. 

Next, VA has conceded that the Veteran was exposed to toxins during active duty. As such, service connection based on TERAs will be considered. Weighing against the claim, a June 2025 VA examiner opined that it was less likely than not that OSA was caused by the indicated TERAs after considering the
 examining physician noted a history of headaches and dizzy spells, he did not identify any symptom or diagnoses reasonably attributable to OSA, such as snoring or daytime fatigue. 

Moreover, the Veteran does not contend that OSA began during service. As such, the medical evidence does not support the in-service incurrence of OSA. Therefore, the medical evidence does not support service connection for OSA on a direct basis. 

Next, VA has conceded that the Veteran was exposed to toxins during active duty. As such, service connection based on TERAs will be considered. Weighing against the claim, a June 2025 VA examiner opined that it was less likely than not that OSA was caused by the indicated TERAs after considering the total potential exposure through all deployments and the synergistic, combined effect of all TERAs. 

After a review of the medical evidence and relevant medical literature, the examiner explained there was no medical or scientific evidence which supported a relationship between the development of OSA and toxic exposures in the Republic of Vietnam. Further, the examiner noted that there were outside risk factors including obesity, male gender, deviated septum, and age that far outweighed the factors identified in the TERAs. There are no conflicting medical opinions of record. As such, the medical evidence does not support service connection for OSA based on toxic exposure. 

Next, the Veteran's main contention is that OSA is secondary to service-connected disabilities, to include diabetes mellitus (DM). In support of the claim, a December 2025 private consultant opined that OSA was at least as likely as not secondary to service-connected DM. Specifically, the consultant reviewed the relevant medical literature and noted that OSA was a long-term sleep disorder which caused repeated airway blockages resulting in shallow breathing, low oxygen levels, poor sleep quality, and strain on the body over time. 

They explained that the prevalence of OSA, DM, and obesity has risen sharply in recent decades. While the consultant stated that obesity and aging were shared risk factors for both OSA and DM, they further noted that there was emerging medical evidence to show that the relationship between OSA and DM was not solely attributable to obesity. They cited to a medical study which showed that the association between OSA and DM existed even after adjusting for body mass index (BMI), which suggested an independent bidirectional relationship. 

The consultant explained that DM often led to diabetic autonomic neuropathy, which disrupted the autonomic regulation of breathing and upper airway muscle tone. They noted that this made the airway more prone to collapse during sleep. Additionally, the consultant indicated that chronic glycemic variability could lead to sensorimotor dysfunction of the upper airway and promoted airway collapsibility. 

Further, the consultant cited medical studies which showed that individuals with DM had a markedly higher prevalence of OSA compared to the general population. This study included a higher prevalence of OSA even in individuals with a normal BMI, indicating that DM could lead to OSA independent of obesity. Next, the consultant opined that the Veteran's medical history closely aligned with the patterns described in the clinical research. Specifically, they found that impaired glucose regulation led to the gradual onset and progressive worsening of OSA symptoms. 

Further, the December 2025 private consultant noted that DM triggered complex metabolic changes over time, which promoted excess fat accumulation and the development of obesity. Accordingly, they explained that this progressive metabolic shift caused difficulty controlling weight gain. They stated that the Veteran had been unable to achieve significant or sustained weight loss, despite consistent efforts to manage his weight through medically recommended diets, structured meal plans, and intermittent exercise. Further, they found that the DM peripheral neuropathy limited the ability to increase activity or burn calories, which further led to difficulty losing weight. They cited studies which showed that decreased physical activity directly led to weight gain. 

Additionally, the consultant noted that obesity was a well-established risk factor for OSA. They indicated that research demonstrated a high prevalence of obese individuals who developed OSA. 

In sum, the December 2025 consultant concluded that DM at least as likely as not contributed directly to the development and progression of OSA through impaired respiratory control and upper-airway muscle tone. Further, they found that DM led to peripheral neuropathy which decreased the Veteran's mobility and activity levels, which led to obesity and increased risk of OSA. 

After review, the Board affords the December 2025 private opinion lesser probative value. In formulating the opinion, the private consultant relied upon medical studies which found an "association" between OSA and DM; however, these studies did not find a "causative" relationship between the disorders. Specifically, the finding that individuals with DM had a higher prevalence of OSA compared to the general population does not show causation. In sum, the consultant based this opinion in part on a correlation between OSA and DM and not a cause-and-effect
-airway muscle tone. Further, they found that DM led to peripheral neuropathy which decreased the Veteran's mobility and activity levels, which led to obesity and increased risk of OSA. 

After review, the Board affords the December 2025 private opinion lesser probative value. In formulating the opinion, the private consultant relied upon medical studies which found an "association" between OSA and DM; however, these studies did not find a "causative" relationship between the disorders. Specifically, the finding that individuals with DM had a higher prevalence of OSA compared to the general population does not show causation. In sum, the consultant based this opinion in part on a correlation between OSA and DM and not a cause-and-effect relationship. 

Next, the consultant's rationale is speculative throughout the opinion. For example, they stated that the medical studies demonstrated that DM "even in the absence of obesity, can directly contribute to sleep apnea by impairing respiratory regulation and diminishing baseline airway muscle tone." This is speculative as the consultant finds only that DM "can" directly contribute to OSA. Further, they noted that DM was "an important independent predictor of OSA." This finding is insufficient to establish a causative relationship. Thus, the Board finds these opinions of lesser probative value. As such, the weight of the medical evidence does not support service connection for OSA as secondary to DM. 

Further, service connection may be granted on a secondary basis through the intermediary step of obesity. In a November 2025 brief, the Veteran argued that the service-connected disabilities severely compromised his ability to ambulate and exercise, causing weight gain and the development of OSA. He noted that he weighed 147 pounds at service enlistment but now weighed 278 pounds at the time of the claim. 

As noted above, the December 2025 private consultant opined that DM resulted in diabetic peripheral neuropathy, which significantly contributed to progressive weight gain and obesity, which was linked to the development of OSA. However, the private consultant relied upon generalized medical studies which showed that individuals with less physical activity were at risk for the development of OSA. This opinion relied on a correlation and not a cause-and-effect relationship. 

Moreover, the private consultant did not discuss any specifics related to the Veteran's dietary habits or exercise routine. Rather, they relied on a group of medical studies which showed that DM caused weight gain through metabolic changes and that diabetic nerve pain impaired mobility, decreased physical activity levels, and led to weight gain. While they noted that the Veteran had attempted to follow diets unsuccessfully and could not remain active due to pain and nerve issues, they did not actually discuss the Veteran's specific diet or discuss any low impact exercises that he could potentially perform despite his disabilities. 

Next, the medical evidence weighs against the December 2025 private consultant's opinion that DM caused obesity. Specifically, the clinical treatment records reflect that the Veteran has been obese throughout the period on appeal; however, the medical evidence does not suggest that obesity was the result of a service-connected disability. 

Rather, the evidence shows that the Veteran has been encouraged to exercise and diet to maintain a healthy weight. For example, a January 2022 clinical treatment note indicated that he was insufficiently active as he only exercised 3 days per week with 20 minutes of exercise per session. In March 2025, a clinician encouraged a well-balanced, low carbohydrate diet with regular exercise. Further, the Veteran indicated that he exercised at least 30 minutes or more, 4 days per week, at that time. The clinical treatment records contain no indication that he was unable to exercise or diet to control weight due to any service-connected disabilities and, in fact, suggested that he regularly exercised.

Further, even considering that the Veteran may experience some degree of limitation in exercise due to service-connected disabilities, the VA examiners have not found that he was unable to manage his weight due to these symptoms. For example, a July 2024 VA examiner noted that diabetic peripheral neuropathy resulted in pain, numbness, and paresthesias which caused functional impact including difficulty holding items normally. 

In addition, an April 2025 VA examiner noted that the Veteran could only walk very limited distances due to peripheral neuropathy in the feet before needing to take a break; however, these examiners did not find that the Veteran could not complete any form of exercise due to these symptoms. 

In addition, a July 2024 VA examiner did not indicate that the Veteran was unable to lose weight or control his diet due to symptoms of DM. While his symptoms may impact certain choices and limit his ability to perform certain forms of exercise, the Board finds that the decision to exercise, diet, and live a healthy lifestyle remains in his control. 

As such, the medical evidence does not reflect that the Veteran's obesity was caused by or aggravated by service-connected disabilities. The weight of the
 VA examiner noted that the Veteran could only walk very limited distances due to peripheral neuropathy in the feet before needing to take a break; however, these examiners did not find that the Veteran could not complete any form of exercise due to these symptoms. 

In addition, a July 2024 VA examiner did not indicate that the Veteran was unable to lose weight or control his diet due to symptoms of DM. While his symptoms may impact certain choices and limit his ability to perform certain forms of exercise, the Board finds that the decision to exercise, diet, and live a healthy lifestyle remains in his control. 

As such, the medical evidence does not reflect that the Veteran's obesity was caused by or aggravated by service-connected disabilities. The weight of the medical evidence does not indicate that he cannot maintain a healthy weight due to his disabilities. 

In all, the Board finds that the December 2025 private consultant's medical conclusions regarding a connection between OSA and DM are of lesser probative value because the conclusions are based on an understanding of the Veteran's disability history not supported by the record. Accordingly, the Board affords the December 2025 private consultant's opinion regarding obesity and limited physical activity lesser probative value. Therefore, the medical evidence does not support service connection for OSA through the intermediary step of obesity. 

The Board notes that a VA medical opinion was not obtained regarding secondary service connection for OSA. Under AMA, appeals can only be remanded for pre-decisional duty to assist errors. To the extent that the Veteran provided a December 2025 private medical opinion regarding secondary service connection, this evidence was submitted during the evidence submission window after the rating decision on appeal. 

While the Board may consider evidence received during an AMA evidentiary window in adjudicating a claim, it may not remand to correct a pre-decisional duty to assist error based solely on evidence or argument received after the AOJ decision on appeal. Therefore, a remand for a VA examination is not required. 

Moreover, the Board has considered the lay statements that OSA was caused by service. While the Veteran is competent to report symptoms and describe observations as this requires only personal knowledge as it comes to him through his senses, he is not competent to offer an opinion as to the etiology of the current disorder due to the medical complexity of the matter involved. Further, he is not competent to make a medical diagnosis of OSA based on these observed symptoms. 

Such competent evidence concerning the nature and extent of the Veteran's OSA has been provided by the medical personnel who examined him during the current appeal, and who rendered pertinent opinions in conjunction with the evaluations. 

Their findings (as provided in the examination reports, sleep study, and other clinical evidence) directly address the criteria under which this disorder is evaluated. The VA medical professional explained their reasoning based on an accurate characterization of the evidence. Therefore, the Board attaches greater probative weight to the VA examination report and clinical findings than to the lay statements regarding etiology. 

In sum, after a careful review of the record, the evidence weighs persuasively against the claim for service connection and there is no doubt to be resolved. As such, the appeal is denied.

Finally, the Veteran has not raised any other issues, nor have any other issues been reasonably raised by the record, for the Board's consideration. See Doucette v. Shulkin, 28 Vet. App. 366, 369-370 (2017) (confirming that the Board is not required to address issues unless they are specifically raised by the claimant or reasonably raised by the evidence of record).

REASONS FOR REMAND

As to the claim for service connection for headaches, the AOJ denied the claim in a July 2025 on the basis that headaches were not shown service; however, the STRs show that the Veteran sought treatment in November 1965 for complaints of dizziness and headaches over the past two months. Further, at the conclusion of the November 1967 separation examination, the physician noted a history of headaches and dizzy spells. As such, the medical evidence shows the in-service incurrence of headaches. 

While the AOJ obtained a medical opinion related to toxic exposure, there is no medical opinion for direct service connection. This constitutes a duty to assist error. Therefore, a remand is warranted so that a medical opinion may be obtained to assess the etiology of the claimed headache disorder. 

The matter is REMANDED for the following action:

Direct the claims file to a clinician to address the etiology of a headache disorder. Applying general medical principles, the clinician's experience, and the Veteran's lay statements, the clinician is asked to address the following: 

"	What is the medical probability (that is, is there a likelihood that is at least approximately balanced, or nearly equal, or higher) that tension headaches, diagnosed in approximately May 
 obtained a medical opinion related to toxic exposure, there is no medical opinion for direct service connection. This constitutes a duty to assist error. Therefore, a remand is warranted so that a medical opinion may be obtained to assess the etiology of the claimed headache disorder. 

The matter is REMANDED for the following action:

Direct the claims file to a clinician to address the etiology of a headache disorder. Applying general medical principles, the clinician's experience, and the Veteran's lay statements, the clinician is asked to address the following: 

"	What is the medical probability (that is, is there a likelihood that is at least approximately balanced, or nearly equal, or higher) that tension headaches, diagnosed in approximately May 2015, were due to or the result of complaints of headaches and dizzy spells during service between December 1964 and December 1967? 

A rationale must be provided for all opinions. 

 

 

L. HOWELL

Veterans Law Judge

Board of Veterans' Appeals

Attorney for the Board	Kokolas, Thomas

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.