Petitioner seeks review of a final order of the Psychiatric Security Review Board (PSRB) ordering that he continue under its jurisdiction. We reverse and remand.

On April 5, 1990, petitioner was found guilty except for insanity1 of three felonies and two misdemeanors. As a result, he was placed under the jurisdiction of PSRB and committed to the Oregon State Hospital.2 On June 22, 1990, he had an initial hearing before PSRB, ORS 161.341(7)(a), which found that petitioner is affected by a mental disease or defect and ordered that his commitment be continued.

Petitioner contends that there is not substantial evidence to support PSRB’s finding that he is affected by a mental disease or defect. PSRB argues that, because petitioner did not “formally apply, pursuant to ORS 161.341(4), to PSRB for an order of discharge or conditional release,” it was not required at the initial hearing to make a finding that petitioner is affected by a mental disease or defect. PSRB maintains that, pursuant to ORS 161.341(1), it is required only to determine at an initial hearing that

“the person presents a substantial danger to others and is not a proper subject for conditional release.” (Emphasis supplied.)

ORS 161.341(7)(a) provides:

“In no case shall any person committed by the court under ORS 161.327 to a state hospital * * * be held in the *583hospital for more than 90 days from the date of the court’s commitment order without an initial hearing before the board to determine whether the person should be conditionally released or discharged.”

ORS 161.341(7)(a) does not specifically require the finding of mental disease or defect. It does require that an initial hearing be held and that PSRB determine whether to discharge or conditionally release the person. ORS 161.351(1) provides:

“Any person placed under the jurisdiction of the Psychiatric Security Review Board pursuant to ORS 161.336 or 161.341 shall be discharged at such time that the board, upon a hearing, shall find by a preponderance of the evidence that the person is no longer affected by a mental disease or defect or, if so affected, no longer presents substantial danger to others which requires regular medical care, medication, supervision or treatment.” (Emphasis supplied.)

The finding of mental disease or defect is required at the initial hearing, because PSRB is required at that hearing to determine if a person under its jurisdiction may be discharged, which requires a finding of whether the person is affected by a mental disease or defect.3 See Martin v. PSRB, 103 Or App 385, 797 P2d 401 (1990), rev’d on other grounds 312 Or 157, 818 P2d 1264 (1991).

PSRB found:

“[Petitioner] is affected by a mental disease or defect as demonstrated by the underlying facts shown by the evidence, including the testimonies of Terrance Lally, Ph.D., and John E. Meyer, M.D., as well as Dr. Meyer’s report as found in Exhibits 10 and 12, and the report of Dr. Norman Janzer, M.D., as found in Exhibit 9.”

The state introduced extensive evidence that petitioner had previously suffered from a mental disease or defect. The *584evidence consisted of a prior diagnosis made during a previous commitment in 1985, evidence concerning petitioner’s behavior during the criminal episode resulting in this commitment and evidence relating to petitioner’s mental state when the court placed him under the jurisdiction of PSRB. However, that evidence is not itself sufficient to prove petitioner’s mental state at the time of the hearing. The state’s only evidence concerning that is the testimony of Meyer and Lally. Meyer testified that petitioner suffers from “possible bipolar disorder, presently in remission.” (Emphasis supplied.) Lally was “leaning towards finding that [petitioner] is not suffering from a mental illness,” although, because of insufficient time to formulate a diagnosis, he was not able to rule out the “tentative diagnosis of schizoaffective disorder or manic depressive illness.” (Emphasis supplied.) The state’s evidence establishes, at best, only a possibility that petitioner is affected by a mental disease or defect, not that he is. PSRB’s finding that petitioner is affected by a mental disease or defect is not supported by substantial evidence. ORS 183.482(8)(c); Valleur v. Psychiatric Review Board, 43 Or App 843, 845, 604 P2d 439 (1979).

Reversed and remanded for proceedings not inconsistent with this opinion.

dissenting.

I do not believe that the majority opinion holds together. To begin with, it may be based on a faulty premise. It is difficult to say from petitioner’s brief whether he seeks a conditional release or a complete discharge. At the hearing, petitioner’s attorney stated his position:

“My — at this time my client is requesting that he be discharged or, in the alternative, that he be found appropriate for conditional release and allowed 90 days within which to prepare and submit a conditional release plan for your review.” (Emphasis supplied.)

However, on appeal, petitioner’s assignment of error specifically refers to the proceeding as a request for discharge:

“[PSRB] erred in denying [petitioner’s] request for discharge, by finding that Petitioner was affected by a mental disease or defect.” (Emphasis supplied.)

*585That is much more than a mere semantic difference. The terminology used by petitioner is very significant in one important particular: allocation of the burden of proof. If this were an initial hearing under ORS 161.341(7)(a), in which petitioner was seeking a conditional release, the burden would have been on the state to show that petitioner continued to be affected by a mental disease or defect. OAR 859-50-055(1), (4).1 Given what it perceives to be equivocal medical and psychiatric testimony, the majority has concluded that the state did not prove the continuing existence of a mental disease or defect. If, on the other hand, this was a hearing on petitioner’s application for discharge under ORS 161.341(4) —which I think it probably was —petitioner would have had the burden to prove that he no longer suffered from the mental disease or defect that originally caused him to be placed under PSRB’s jurisdiction. See n 1, supra; ORS 161.341(5); Baldwin v. PSRB, 97 Or App 367, 371, 776 P2d 577 (1989). On what the majority has characterized as a tentative record, petitioner likewise would not have carried his assigned burden.

Assuming, for the sake of argument, that the majority has correctly assigned the burden of proof, I believe that petitioner still loses because of an even more fundamental flaw. He did not argue at the hearing that he is no longer affected by the mental disease or defect that resulted in his commitment. Instead, he contended there, and here, that he has never suffered from any type of mental disease or defect and that his attorney did not explain the consequences of making that defense at trial.2 In Martin v. PSRB, 103 Or App *586385, 388, 797 P2d 401 (1990), rev’d on other grounds 312 Or 157, 818 P2d 1264 (1991), a post-conviction decision, we held that a contention that the petitioner’s condition was, and always has been, a personality disorder rather than a disease or defect, was an “impermissible collateral attack on the determination that was made by the trial court that ordered the commitment.” The Supreme Court disagreed with our understanding of the petitioner’s argument and reversed, concluding that the petitioner did not actually challenge the trial court’s determination, but simply argued that his condition had changed as of the time of the hearing. 312 Or at 164. On that point, therefore, Martin was reversed on a factual determination. However, the basic rule from our decision in Martin remains: At a post-commitment hearing, the petitioner may not collaterally attack the original determination of the trial court by claiming that he has never actually suffered from the mental condition that he claimed at trial must entitle him to an insanity defense. Instead, he must show that he no longer suffers from that condition. Because petitioner clearly failed to make that showing, he loses.

When all is said and done, it looks to me that the real thrust of this appeal is petitioner’s claim that he was denied effective assistance of counsel. If that is so, he clearly has chosen the wrong forum to litigate that question.

For any or all of the above reasons, I would affirm PSRB’s order. Accordingly, I must respectfully dissent.