Vicki Banks appeals the district court’s3 grant of summary judgment to the Social Security Administration, affirming the Commissioner’s denial of disability insurance benefits and supplemental security income benefits. We affirm.
I.
Vicki Banks was born on July 30, 1957. She has been blind in her left eye since she was involved in an auto accident as a baby. The accident also fractured her skull, requiring drainage of a subdural hematoma, which was successfully treated. Banks attended school through the eleventh grade. She was enrolled in special education classes throughout her schooling, where she had problems in all subjects. She began working as a janitor during her junior year in high school and kept that job for eight years until 1982. She had no significant work history from 1982 until 1988, when she again began working as a janitor. She was laid off from that job on *822April 30, 1995, her alleged disability onset date.
Banks used heroin for approximately 20 years, reflected in the record as a history of opioid dependence. Banks told one psychologist that she was laid off because of her drug use. The opioid dependance is now in remission, and Banks has been drug-free since July 1996 when she began group therapy and daily methadone treatments. She still attends the group sessions and receives daily methadone treatments.
Banks applied for disability benefits and supplemental security income benefits on September 4, 1996. Banks complained of pain in her right hand at her September 25, 1996, disability examination, which was diagnosed as mild carpel tunnel syndrome (CTS) on October 8, 1996. She has never been treated for CTS or been restricted from any activity because of that diagnosis, however. Banks also complained of headaches during the disability examination. She again complained of headaches during an examination on November 15, 1996, at which time she received a 5-day prescription for Propranolol. It is unclear from the record how long Banks took Proprano-lol for her headaches. According to her outpatient psychiatric records, she was apparently taking it in January 1997, and she listed it as a medication she was currently taking when she completed her application for hearing dated June 13, 1997. She did not mention Propranolol at the administrative hearing, however, stating only that she took Tylenol for her headaches, which sometimes alleviated her pain.4
Banks sought psychiatric treatment for depression between January and April 1997 and was placed on antidepressants in February 1997. Banks reported to two different doctors, in April and June 1997, that the medications improved her depression symptoms. She also reported that the medications permitted her to sleep better and allowed her to be involved in her church.
The Social Security Administration sent Banks to Dr. Paxton Small for psychological testing and a Wechsler Adult Intelligence Scale-Revised (WAIS-R), or IQ, examination on November 15, 1996. Banks scored 66 on the Verbal portion, 66 on the Performance portion, and 64 on the Full Scale portion of the test. Although Dr. Small diagnosed Banks in the “Mild Range of Mental Retardation” based on these scores, he noted that “[s]he probably function[ed] at the low level of the Borderline Range of Intellectual Functioning.” (R. at 172.) Dr. Small thought that the “IQ scores [were] probably somewhat depressed because of her lack of motivation and agitated depression.” (Id.) He also noted that she was unable to reliably repeat the alphabet or count backwards from 20.
Banks underwent a second psychological examination on April 7, 1997, with Dr. Gregory Sisk, again taking the WAIS-R. She received the same overall scores as on the IQ test performed by Dr. Small, although the subscores were somewhat different. Banks reported to Dr. Sisk that she had been depressed all of her life and that the antidepressants helped her moods. Like Dr. Small, Dr. Sisk diagnosed Banks with Mild Mental Retardation, but commented that she “does not appear limited intellectually when she is engaged in conversation” and that her quickness to give up may have produced scores that underestimated her true abilities. (R. at 193.) Dr. Sisk also noted that Banks’ subscores were all well below average and consistent *823with her placement in special education throughout school. Dr. Sisk observed that Banks had “spent much of her recent time trying to convince others that she is disabled ... and [that] she may be more interested in proving that she cannot work than she is in actually obtaining] training and a job.” (Id. at 194.)
Banks was initially denied disability benefits and supplemental security income benefits on October 6, 1996, and again on reconsideration on December 5, 1996, following Dr. Small’s examination. Banks then sought a hearing before an administrative law judge (ALJ). Following the hearing, the ALJ propounded interrogatories to a vocational expert (VE), who opined that Banks could not perform her prior job or any other job in the national economy. The ALJ rendered his decision on December 5, 1997, and determined that Banks was not under a disability because she did not meet a listed impairment under the regulations and that she could return to her former occupation as a janitor. The ALJ rejected Banks’ IQ scores as invalid and, in so doing, found that Banks did not meet the listed impairment at § 12.05(C) for mental retardation. See 20 C.F.R. Pt. 404, Subpt. P, App. 1, § 12.05(C) (1996). The ALJ rejected the VE’s opinion because the ALJ believed the VE assumed functional limitations secondary to Banks’ borderline intellectual functioning, which the ALJ did not feel were supported by Banks’ actual limitations and abilities. The Appeals Council declined to review the ALJ’s decision, making the ALJ’s decision the final decision of the Commissioner. Banks sought further review in the district court, which affirmed the ALJ’s decision, including the finding that the IQ scores were invalid. The district court found alternatively that even if the IQ scores were valid, her other impairments did not meet the second prong of § 12.05(C) and that substantial evidence in the record supported the ALJ’s determination that Banks could return to her prior work. Banks appeals.
II.
Banks argues on appeal that the ALJ’s finding that she does not meet the listed impairment for mental retardation is based on improper legal standards and is not supported by substantial evidence, that the district court erred in finding that the ALJ did not have to rely on the VE to determine whether she could perform her prior work, and that the AL J’s finding that she does not have any nonexertional limitations is not supported by substantial evidence. We review de novo the district court’s decision to uphold the denial of social security benefits. We must determine whether the ALJ’s decision is based on legal error and determine if substantial evidence in the record supports the denial. Lowe v. Apfel, 226 F.3d 969, 971 (8th Cir.2000). Substantial evidence is something less than a preponderance, but enough that a reasonable mind would conclude that the evidence supports the decision. Our review ultimately requires us to review the administrative record as a whole, fairly considering the evidence that detracts from the decision as well as the evidence that supports it. Bryant v. Apfel, 141 F.3d 1249, 1251 (8th Cir.1998); Johnson v. Chater, 108 F.3d 942, 944 (8th Cir.1997). “As long as substantial evidence in the record supports the Commissioner’s decision, we may not reverse it because substantial evidence exists in the record that would have supported a contrary outcome, ... or because we would have decided the case differently.” Roberts v. Apfel, 222 F.3d 466, 468 (8th Cir.2000).
Under the familiar five-part analysis utilized in social security disability cases, the ALJ must determine, sequentially, the following: 1) whether the claimant is employed; 2) whether the claimant has a *824severe impairment; 3) whether the impairment meets a listed impairment; 4) whether the impairment prevents the claimant from doing past work; and 5) whether the impairment prevents the claimant from doing any other work. See 20 C.F.R. § 404.1520(a)-(f) (1996). If the claimant fails at any step, the ALJ need not continue. The claimant carries the burden of establishing that she is unable to perform her past relevant work, i.e., through step four, at which time the burden shifts to the Commissioner to establish that she maintains the residual functional capacity to perform a significant number of jobs within the national economy. See Singh v. Apfel, 222 F.3d 448, 451 (8th Cir.2000). The ALJ determined that Banks met the first two steps. It is at step three that Banks first takes issue with the ALJ’s findings.
A.
If the ALJ finds that the claimant meets a listed impairment at step three, the ALJ must make a finding of disability. See 20 C.F.R. § 404.1520(d). The relevant listed impakment in this case is § 12.05, mental retardation. See 20 C.F.R. Pt. 404, Subpt. P, App. 1. Mental retardation is “a significantly subaverage general intellectual functioning with deficits in adaptive behavior initially manifested during the developmental period (before age 22).” Id. § 12.05. The required level of severity is met if the following relevant conditions are found: (a) a valid IQ between 60 and 70, and (b) “a physical or other mental impairment imposing additional and significant work-related limitation of function.” Id. § 12.05(C). The ALJ found the first prong unmet because he found that Banks’ IQ scores were invalid based on Dr. Small’s and Dr. Sisk’s comments. The district court found substantial evidence to support that conclusion, and went on to hold that even if the IQ scores were valid, the second prong was not met because the additional alleged disabilities did not significantly limit Banks’ ability to work.
Banks first argues that the district court erred by reaching for and making the alternative finding that she had no additional and significant work-related limitations. “[A] reviewing court may not uphold an agency decision based on reasons not articulated by the agency,” when “the agency [has] fail[ed] to make a necessary determination of fact or policy” upon which the court’s alternative basis is premised. Healtheast Bethesda Lutheran Hosp. and Rehab. Ctr. v. Shalala, 164 F.3d 415, 418 (8th Cir.1998) (discussing the limitations on the rule made by the Supreme Court in S.E.C. v. Chenery Corp., 318 U.S. 80, 63 S.Ct. 454, 87 L.Ed. 626 (1943)). Our review of the ALJ’s decision, in which he analyzed each of Banks’ alleged disabilities, reveals that the ALJ did in fact make the factual findings necessary for the district court’s alternative holding. Thus, the general limitation on a reviewing court’s ability to use reasons not utilized by the agency is not applicable to this case.
Relying on Cook v. Bowen, 797 F.2d 687, 690-91 (8th Cir.1986), Banks argues alternatively that because the ALJ found that her impairments were severe at step two, she has met the second prong of § 12.05(C) as a matter of law. A closer look at Cook and the cases that follow it reveals that this is true only if the finding of severe impairments at step two is based on impairments other than mental retardation. See, e.g., Bryant, 141 F.3d at 1252 (holding that where a severe impairment is found at step two based on a learning disability and migraine headaches, but the headaches posed no more than a slight limitation of function, the second prong of § 12.05(C) was not met). Thus, although the district court found that “[t]he medical evidence on the record supports the ALJ’s determination that plaintiff had severe im*825pairments” at step two (Add. at 6), we must look to see what about Banks’ combination of impairments made them severe and whether the impairments other than her mental retardation impose additional and significant work-related limitations.
Banks claims that she is additionally limited by depression, headaches, mild carpel tunnel syndrome, blindness in one eye, a history of a childhood skull fracture, and a history of opioid dependence. Based on the factual findings made by the ALJ, the district court found that each of these additional disabilities did not significantly limit Banks’ ability to work. We agree. There is no evidence that Banks is limited in any way by the childhood skull fracture. Banks has been blind since childhood and has successfully worked for years with that condition. Her opioid dependence is in remission and being successfully treated. Banks had each of these conditions while she worked as a janitor. She does not allege that any of them made her unable to perform her prior work; rather, she told Dr. Sisk that she was “let go” because she was strung out on drugs. These alleged limitations are insufficient to satisfy the second prong of § 12.05(C). See Buckner v. Apfel, 213 F.3d 1006, 1012 (8th Cir.2000) (noting that the claimant’s employment history suggested that her ability to work was not more than slightly affected by her physical impairments); Hinkle v. Apfel, 132 F.3d 1349, 1353 (10th Cir.1997) (following Eighth Circuit precedent and holding that where there is no evidence that the claimant’s condition has deteriorated since he last worked, the second prong of § 12.05(C) was not satisfied); cf. Sird v. Chater, 105 F.3d 401, 402 (8th Cir.1997) (holding that the second prong of § 12.05(C) was met where the claimant had been “additionally impaired in the period since he performed past relevant work”).
Banks’ remaining limitations include depression, headaches, and mild carpel tunnel syndrome in her right wrist. She reported to Dr. Sisk that she had been depressed most of her life and that she suffered from a nervous breakdown in 1987 after her father was killed. However, she never sought treatment at that time and worked from 1988 until 1995 at the same job, despite any alleged depression. The record further reveals that to the extent Banks’ depression has worsened since she last worked, it is related to dealing with her drug addiction and being drug-free. She stopped taking drugs in July 1996 when she began group therapy and daily methadone treatments. She sought psychiatric treatment in January 1997 related to childhood abuse she had suppressed with her drug addiction. She was prescribed antidepressants in February 1997. She told her psychologist on March 21, 1997, that she was doing well, was attending church and Bible study, and was doing volunteer work by visiting elderly people in a nursing home and working with HIV patients. She reported in April and June 1997 that the drugs were helping her depression. She was terminated as a psychiatric patient in April 1997 because she missed six sessions, and she apparently has never sought further psychiatric treatment. Thus, less than twelve months after taking control of her drug addiction, which apparently precipitated her recent bout of depression, Banks’ depression was controlled with medication. Although Banks’ attorney asserted during oral argument that Banks’ depression is still debilitating and it is unclear whether it is treatable, the citations to the record relied upon to support this argument involve records made prior to the time Banks received the antidepressants.
The only evidence of disabling depression is Banks’ statement at the hearing, *826only a few months after she told doctors she was doing better, that she felt so depressed she did not know if she was going to live. The ALJ discredited her claims of disabling depression as inconsistent with her daily activities, particularly her level of church involvement, and as inconsistent with the her failure to seek additional psychiatric treatment. As noted by the ALJ, Banks’ depression improved after she started the antidepressants, and she received treatment for her depression for only three months, missing six of her scheduled appointments during that time. We hold that there is substantial evidence in the record to support the ALJ’s factual findings upon which the district court relied to conclude that Banks’ depression does not impose significant limitations on her ability to work. See Holland v. Apfel, 153 F.3d 620, 622 (8th Cir.1998) (holding that lack of evidence of ongoing treatment for depression supported determination that claimant failed to meet the second prong of § 12.05(C)); cf. Gowell v. Apfel, 242 F.3d 793, 798 (8th Cir.2001) (concluding that failure to seek psychiatric treatment, coupled with extensive work history, supported finding that claimant’s alleged depression was not a severe impairment). See also 20 C.F.R. Pt. 404, Subpt. P, App. 1 § 12.00(A) (requiring limitations based on mental disorders to last, or be expected to last, at least 12 months).
Banks also complains of disabling headaches, which she labels as migraines. Banks characterizes them as lifelong and attributes them to the head injury she suffered as a baby, although no doctor has made that etiological finding. Banks experienced a brief blackout in 1996 when she fell at church, which she attributed to her headaches. There is no evidence that Banks suffered from any other blackouts. Banks received at least one prescription for Propranolol in November 1996, which is prescribed for migraine headaches, see Physicians’ Desk Reference 3307 (53d ed.1999), though as we noted above, it is unclear from the record how long she took that medication. At the hearing, she testified only that she took Tylenol, which was sometimes effective and sometimes not. No doctor has ever diagnosed a neurological abnormality related to her headaches. The ALJ concluded from his review of the record that Banks’ complaints about her headaches, both to medical professionals and at the hearing, were vague and that her failure to follow up on treatment undermined the alleged severity of the headaches. The record evidence supports the ALJ’s conclusion that “[t]he evidence simply fails to establish that the claimant’s headaches result in any more than a slight, if any[,] limitation in her ability to engage in work-related activities” (Add. at 18) and provides sufficient support for the district court’s conclusion that Banks’ headaches did not pose a significant restriction on her ability to work. See Buckner, 213 F.3d at 1012 (holding that ALJ’s finding of no § 12.05(C) additional and significant impairment was supported by substantial evidence where medical evidence contradicted claimant’s complaints of obesity, headaches, dizziness and sore hands).
Banks was diagnosed with mild carpel tunnel syndrome in her right wrist on October 8, 1996, after she last worked. However, she has never been restricted by a doctor or prescribed any treatment for the mild carpel tunnel syndrome. The diagnosing doctor noted that tests showed only “slight delay in digital latency ... [which] is consistent with mild right carpel tunnel syndrome.” (R. at 162.) Banks has not sought further treatment and does not even report taking medication for the pain in her hands. At the administrative hearing, she testified that she gets sharp pains in her hands, that it is hard to use them sometimes, and that sometimes she can hardly write with her left, nondomi-nant hand because of the pain. The ALJ *827discredited Banks’ subjective complaints of pain in her hands, noting that her diagnosis of right carpel tunnel syndrome was mild, surgery had not been recommended, and no doctor had ever placed restrictions on her activities related to the carpel tunnel syndrome. We conclude that substantial evidence in the record supports the ALJ’s fact findings and properly forms the basis for the district court’s conclusion that Banks’ mild carpel tunnel syndrome is not a significant limitation on her ability to work. See Holland, 153 F.3d at 622 (rejecting § 12.05(C) claim where doctor released claimant to work following wrist surgery although he found twenty percent permanent disability; doctor’s only recommendation was to use a wrist lacer when lifting heavy objects); Hinkle, 132 F.3d at 1353 (holding that the second prong of § 12.05(C) was not met despite claimant’s back pain because claimant still had a fair tolerance for work-related activities and his doctors noted no restriction in movement).
Having found that none of Banks’ alleged impairments meet the second prong of § 12.05(C) individually, we look at whether any of them in combination sufficiently limit Banks’ ability to work. As we have noted, Banks worked extensively with all of the alleged impairments to some degree, except possibly the mild carpel tunnel syndrome, which was diagnosed after she last worked. She worked as a janitor for two extended periods of time, first for eight years and most recently for seven years, earning over $10,000 per year during her most recent employment. Her ability to work with these impairments, coupled with evidence that Banks is “more interested in proving that she cannot work than she is in actually obtaining training and a job,” (R. at 194), supports the conclusion that none of Banks’ impairments significantly restrict her ability to work. See Buckner, 213 F.3d at 1012 (“[A]l-though there may be some evidence that [claimant] suffers from a physical or additional mental impairment that limits her ability to work, ... [claimant’s] employment history ... suggests that her ability to work is not more than slightly affected by any physical impairments that she may have.”). Because we believe none of Banks’ impairments, either individually or in combination, rise to the level of significant work-related limitations, we affirm the district court’s alternative holding based on the second prong of § 12.05(C). We therefore decline to address the ALJ’s finding that Banks’ IQ scores were invalid.
B.
Banks next argues that the ALJ was required to rely on the VE’s testimony at step four in assessing whether she could return to her prior relevant work because she has nonexertional, impairments. We begin by noting that it is clear in our circuit that vocational expert testimony is not required at step four where the claimant retains the burden of proving she cannot perform her prior work. See Gowell, 242 F.3d at 799; Gaddis v. Chater, 76 F.3d 893, 896 (8th Cir.1996); Barrett v. Shalala, 38 F.3d 1019, 1024 (8th Cir.1994). Vocational expert testimony is not required until step five when the burden shifts to the Commissioner, and then only when the claimant has nonexertional impairments, which make use of the medical-vocational guidelines, or “grids,”- inappropriate. See Beckley v. Apfel, 152 F.3d 1056, 1059 (8th Cir.1998); Johnston v. Shalala, 42 F.3d 448, 452 (8th Cir.1994).
We have stated in passing that “[t]he testimony of a vocational expert is relevant at steps four and five of the Commissioner’s sequential analysis .... ” Gilbert v. Apfel, 175 F.3d 602, 604 (8th Cir.1999). We have not required it at step four. In Gilbert, the ALJ determined that the claimant’s impairments were not severe at *828step two, although he sought the testimony of a VE at the hearing. We relied on the VE’s testimony that the claimant could not perform prior or any other work, and the ALJ’s failure to explain why he rejected the VE’s opinion, in reversing and remanding for further consideration. Our concern was with the ALJ’s decision to stop the analysis at step two, noting the Social Security Administration’s cautionary rulings recommending that analysis should proceed past step two if there is any doubt about the effect of the claimant’s impairments on her ability to do basic work activities. See id. at 604-05. We also recognized, however, that an ALJ is free to ultimately find fewer or less severe impairments than included in the hypothetical to the VE. Id. at 604.
In this case, the VE based his conclusion that Banks could not perform any work in the economy, including her past work, on “right dominant hand limitation and job base erosion due to borderline intellectual functioning and occasional interactions.” (R. at 145.) The ALJ rejected the VE’s opinion because he believed the VE inappropriately assumed secondary limitations from Banks’ borderline intellectual functioning that were not supported by her actual abilities and limitations. The VE assumed limitations in unskilled occupations, which the ALJ found unsupportable as Banks worked for significant periods of time in unskilled positions with borderline intellectual functioning. The ALJ properly disregarded the VE’s opinion because it is unclear the extent to which the opinion relied on Banks’ borderline intellectual functioning. See Johnson v. Apfel, 240 F.3d 1145, 1148 (8th Cir.2001) (“Since the vocational expert was basing her opinion upon [claimant’s] assertions [regarding depression which the ALJ found unsupported], this portion of the opinion was properly disregarded.”). Because the ALJ was not required to utilize the services of a VE to begin with, he did not err in failing to further clarify the VE’s opinion by eliciting further testimony from the VE. Like any other proffered evidence, the ALJ is free to accept, in whole, in part, or not at all, the VE’s opinion at step four so long as the ALJ explains why the VE’s opinion is treated the way the ALJ treats it. See Gilbert, 175 F.3d at 604 (noting that the ALJ’s conclusory finding that some of the claimant’s alleged impairments were not severe supported his decision to disregard the VE’s opinion to the extent it relied on those impairments); see also Barnett v. Apfel, 231 F.3d 687, 690 (10th Cir.2000) (holding that the ALJ properly rejected VE testimony at step four where the hypothetical included limitations not supported by the record). He did so in this case.
C.
Banks argues that the ALJ’s finding that she did not suffer from any nonexer-tional impairments is not supported by substantial evidence in the record. Using the factors outlined in Polaski v. Heckler, 739 F.2d 1320, 1322 (8th Cir.1984), the ALJ determined that Banks’ subjective complaints were not credible. Banks does not quibble with any of those findings. Rather, she relies on the fact that the ALJ concluded that she suffered from severe impairments at step two, including borderline intellectual functioning and depression, to leap to the conclusion that she is disabled due to these nonexertional impairments. Severe or not, neither impairment prevented Banks from holding two jobs for extended periods of time. For the reasons discussed at length above regarding the second prong of § 12.05(C), we conclude that substantial evidence in the record supports the ALJ’s finding that to the extent Banks suffers from any nonexer-tional limitations, they do not prevent her from performing her past work as a janitor.
*829Finally, Banks argues that the ALJ was required to rely on the testimony of a VE because borderline intellectual functioning and depression are nonexertional impairments which must be evaluated by a VE. Because the ALJ found that Banks could perform her prior work as a janitor, a decision we conclude is supported by substantial evidence in the record, the ALJ was not required to rely on the expertise of a VE, even though some of Banks’ alleged impairments were nonexertional. (See discussion supra § II.B.) As discussed above, it is only yvhen the claimant satisfies her burden of establishing that her nonexertional impairments prevent her from performing her past work and the burden shifts to the Commissioner that the testimony of a VE is required.
III.
For the reasons stated above, we affirm the district court’s judgment.
. The Honorable William A. Knox, United States Magistrate Judge for the Western District of Missouri, to whom the case was referred for final disposition by consent of the parties pursuant to 28 U.S.C. § 636(c).
. Likewise, Banks does not even mention in her briefs the use of Propranolol for her headaches, but argues only that "[s]he takes tyle-nol for relief [from her headaches], but it is often ineffective.” (Appellant Br. at 6.)