MEMORANDUM **

Kurt A. Mundt appeals the decision of the district court affirming the Commissioner of Social Security’s denial of Mundt’s application for disability benefits under Titles II and XVI of the Social Security Act. We review de novo to ensure that the decision was supported by substantial evidence and a correct application of the law. Roberts v. Shalala, 66 F.3d 179, 182 (9th Cir. 1995).

Lay witness testimony as to a claimant’s symptoms or how an impairment affects ability to work is competent evidence that the Secretary must take into account. Nguyen v. Chater, 100 F.3d 1462, 1467 (9th Cir. 1996); 20 C.F.R. §§ 404.1513(d), 404.1545(a)(3). An ALJ may disregard such evidence only upon articulating reasons “that are germane to each witness.” Dodrill v. Shalala, 12 F.3d 915, 919 (9th Cir. 1993).

According to Mundt, the ALJ’s reasoning for disregarding testimony regarding Mundt’s lack of endurance — that the lay witnesses were not knowledgeable in medical or vocational fields — is insufficient because it merely reiterates the witnesses’ lay status. However, the ALJ determined that Mundt’s substance abuse, rather than his medical impairments, was the “major contributor to his moderate difficulties in maintinfing] concentration, persistence and pace.” Substantial evidence supported this finding. Since lay witness testimony regarding symptoms is relevant only to the *772extent that the symptoms are linked to a medically determinable impairment, see 42 U.S.C. § 428(d)(1)(A); 20 C.F.R. § 404.1513(d), the ALJ did not err in not relying upon the lay testimony.

AFFIRMED.