The mental health of veterans—and particularly veterans of Operations Enduring Freedom and Iraqi Freedom (OEF/OIF) —has been a topic of ongoing concern to Members of Congress and their constituents, as evidenced by hearings and legislation. Knowing the number of veterans affected by various mental disorders and actions the Department of Veterans Affairs (VA) is taking to address mental disorders can help Congress determine where to focus attention and resources. Using data from the VA, this brief report addresses the number of veterans with (1) depression or bipolar disorder , (2) posttraumatic stress disorder (PTSD), and (3) substance use disorders; Appendix A discusses important data limitations. For each topic, this report also briefly describes what the VA is doing in terms of screening and treatment; Appendix B lists reports evaluating the VA's efforts. Veterans generally must enroll in the VA health care system to receive medical care; for information about enrollment, health benefits, and cost-sharing, see CRS Report R42747, Health Care for Veterans: Answers to Frequently Asked Questions , by [author name scrubbed] and [author name scrubbed]. From FY2002 through FY2012, 1.6 million OEF/OIF veterans (including members of the Reserve and National Guard) left active duty and became eligible for VA health care; by the end of FY2012, 56% of them had enrolled and obtained VA health care. The VA publishes the cumulative prevalence of selected mental disorders among OEF/OIF veterans using VA health care, based on information in the VA's electronic health records. Systematic information regarding veterans who do not use VA health care is not available. Data about OEF/OIF veterans using VA health care should not be extrapolated to the rest of the OEF/OIF veteran population, or to the broader veteran population. Limitations of the VA's data are discussed in Appendix A . Depression and bipolar disorder are both mood disorders; bipolar disorder includes episodes of both depressed mood (which characterizes depression) and mania (elevated mood or irritability) or hypomania (a milder form of mania). The VA does not present separate prevalence figures for depression and bipolar disorder, nor does it provide the prevalence of depression and bipolar disorder combined; instead, the VA presents the prevalence of affective psychoses , a range of diagnoses including major depressive disorder and bipolar disorder, among others (14%); and depressive disorder not elsewhere classified (NEC) , a diagnosis assigned when a patient reports depressive symptoms that do not meet criteria for other depressive disorders (e.g., major depressive disorder) (22%). The percentages are presented in Figure 1 and Figure 2 .Neither of these categories includes dysthymic disorder (a form of depression), which falls in a category of neurotic disorders (a broad category that also includes panic disorder and generalized anxiety disorder, among others). It is possible that a patient with a diagnosis of one mood disorder reflected in the electronic health record might also have a diagnosis of another mood disorder in the electronic health record; for this reason, the prevalence of affective psychoses (14%) and the prevalence of depressive disorder NEC (22%) should not be summed. These percentages are subject to other important data limitations discussed in Appendix A . Department policy requires an annual depression screening for veterans using VA health care . Depression and bipolar disorder may be treated with medication, psychosocial interventions, or both. The VA's suicide prevention efforts, which are relevant to patients with mood disorders (as well as other veterans), are described in CRS Report R42340, Suicide Prevention Efforts of the Veterans Health Administration , by [author name scrubbed]. All veterans, regardless of enrollment, may use the department's Veterans Crisis Line (1-800-273-8255, option 1), an online chat service ( www.VeteransCrisisLine.net/chat ), and an online suicide prevention resource center ( www.suicideoutreach.org ) maintained jointly with the Department of Defense (DOD). Several reports that have evaluated the department's mental health programs (including treatment for mood disorders and suicide prevention) and offered recommendations are listed in Appendix B . Posttraumatic stress disorder (PTSD)—one of the "signature injuries" of OEF/OIF —is a psychological response to a traumatic event; however, a history of trauma is not enough to establish a diagnosis of PTSD. The diagnosis requires a minimum number of symptoms in each of three categories: reexperiencing (e.g., recurring nightmares about the traumatic event); avoidance (e.g., avoiding conversations about the traumatic event); and arousal (e.g., difficulty sleeping). Symptoms must persist for at least one month and must result in clinically significant distress or impairment in functioning. As illustrated in Figure 3 , the VA reports the prevalence of PTSD among OEF/OIF veterans receiving VA health care in FY2002–FY2012 to be 29%. This percentage is subject to important data limitations discussed in Appendix A . Given the attention on PTSD, it is worth noting that prevalence estimates from other sources (generally not limited to users of VA health care) vary widely. A 2010 RAND analysis of 29 relevant studies found prevalence estimates for PTSD ranging from around 1% to 60% among OEF/OIF servicemembers; variation was attributed in part to the use of different samples and different methods of identifying PTSD. A 2012 report by the Institute of Medicine indicates that recent estimates of PTSD prevalence among OEF/OIF servicemembers and veterans range from 13% to 20%. Department policy requires that veterans new to VA health care receive a PTSD screening, which is repeated every year for the first five years and every five years thereafter, unless there is a clinical need to screen earlier. Department policy also requires that new patients requesting or referred for mental health services receive an initial assessment within 24 hours and a full evaluation within 14 days. Congressional testimony has raised questions about the extent to which these policies are implemented in practice. PTSD treatment provided by the VA includes both medication and cognitive-behavioral therapy (a category of talk therapy). Every VA Medical Center has specialists in PTSD treatment. Some facilities offer specialized PTSD treatment programs of varying intensity and duration, including (among others) PTSD day hospitals (four to eight hours per day, several days per week); evaluation and brief treatment PTSD units (14-28 days); specialized inpatient PTSD units (28-90 days); and PTSD residential rehabilitation programs (28-90 days living in a supportive environment while receiving treatment). Veterans may also receive PTSD treatment at VA community-based outpatient clinics (CBOCs) or at Vet Centers (which are subject to different policies than VA health care facilities). Several reports that have evaluated the VA's PTSD screening and treatment efforts and offered recommendations are listed in Appendix B . Substance use disorders include dependence on and abuse of drugs, alcohol, or other substances (e.g., nicotine). A diagnosis of dependence requires at least three symptoms (e.g., tolerance or withdrawal); substance use that does not meet criteria for dependence, but leads to clinically significant distress or impairment, is called abuse. Each diagnosis is specific to the substance, so an individual may have multiple diagnoses of abuse or dependence—one for each substance (e.g., marijuana dependence and cocaine abuse). Figure 4 and Figure 5 show the prevalence of drug dependence and abuse (respectively) among OEF/OIF veterans using VA health care during FY2002–FY2012. Alcohol dependence (6%) is more common than either drug dependence (3%) or abuse (5%); the prevalence of alcohol abuse was not provided. These percentages are subject to important data limitations discussed in Appendix A . Given the comparatively low rates of drug abuse and dependence (relative to other disorders presented in this report), VA policy does not require routine drug use screening. Department policy does require an annual alcohol screening, which is waived for veterans who drank no alcohol in the prior year. The VA offers medication and psychosocial interventions for substance use disorders, as well as acute detoxification care when necessary. Medication may be used to reduce cravings or to substitute for the drug of abuse (e.g., methadone for heroin users). Psychosocial interventions include (among others) brief counseling to enhance motivation to change; intensive outpatient treatment; residential care (i.e., living in a supportive environment while receiving treatment); long-term relapse prevention; and referral to outside programs such as Alcoholics Anonymous. Several reports that have evaluated the department's alcohol screening and substance use disorder treatment efforts and offered recommendations are listed in Appendix B . Appendix A. Data Limitations In order to understand the limitations of the data presented in this report, it is helpful to understand their sources. The VA identifies PTSD and substance use disorders by searching VA administrative data for diagnosis codes associated with specific conditions (e.g., 309.81 for PTSD). These codes are entered into veterans' electronic medical records by clinicians, in the normal course of evaluation and treatment. The data provided by the VA should be interpreted in light of at least three limitations, each of which is discussed below. First, some conditions may be overstated, because veterans with diagnosis codes for a condition might not have the condition, as a result of provisional diagnoses or noncurrent diagnoses. A provisional diagnosis code may be entered into a veteran's electronic medical record when further evaluation is required to confirm the diagnosis. A diagnosis may be noncurrent when a veteran who had a condition in the past no longer has it. In either case, the code remains in the veteran's electronic medical record. Second, some conditions may be understated, because veterans who have a condition might not be diagnosed (and therefore might not have the diagnosis code in their records), if they choose not to disclose their symptoms. Veterans might not want to disclose information that would lead to a diagnosis of mental illness.