A physician who has examined Khmer Rouge “First Lady” Ieng Thirith said in court yesterday that she would have “great difficulty” testifying in her own defence, casting further doubt on her fitness to stand trial during hearings at Cambodia’s war crimes tribunal.

New Zealand geriatrician John Campbell made the comment when asked by co-defence lawyer Diana Ellis whether Ieng Thirith would be able to testify in her own defence and stand up to cross-examination in her pending trial for war crimes and genocide.

“My assessment at this stage is that she would have difficulty instructing her counsel and participating fully in the trial,” he said. Campbell said his conclusions should not be considered final until “all possible measures have been tried” to improve her condition.

“Until we’ve explored all possibilities and tried all measures to try and improve function, we cannot be definite that she will not be able to participate in her own defence,” he said.

Ieng Thirith has “significant cognitive impairment” from a number of possible causes, Campbell testified on Monday, including an “underlying dementing illness” due “most likely” to Alzheimer’s disease.

Ieng Thirith had been taking three psychotropic medications since 2006 that he said may be contributing to her condition. She stopped taking bromazepam and clonazepam last week and has begun a reduction in quetiapine, described by Campbell as a “major tranquiliser”.

Campbell recommended a three-month trial period for a different drug to address memory-loss symptoms associated with Alzheimer’s or dementia, once Ieng Thirith has stopped taking quetiapine. He said improvement in her condition was “possible, but unlikely”, and noted that “around a third” of patients see improvement.

Anne Heindel, a legal advisor at the Documentation Centre of Cambodia, said the two days of hearings suggested so far that it was “very likely that she’s going to be found unfit” for trial.

Ellis introduced reports in yesterday’s hearing from the head of the detention centre documenting 50 outbursts by Ieng Thirith in which she “insulted” co-defendant Brother No 2 Nuon Chea, guards or S-21 jailer Duch over a nine-month period starting in late 2008.

Campbell testified that when he asked her in a meeting for the date, Ieng Thirith incorrectly gave her birthday. She later – also incorrectly – provided that same date for her wedding day. Yet when Campbell asked her for the actual date of her birthday, she could not answer.

The KR Social Action Minister was “unable to answer the questions about where she was and the purpose of the [detention centre] and why she was there”, Campbell said, and failed to perform “very basic tests”, such as writing a complete sentence of her own choice and following a series of three instructions.

People who had observed Ieng Thirith said she “sometimes talks to herself, usually about the past and her youth” and “can become lost within the detention centre and on occasions does not recognise her own room”, according to Campbell’s report.

Campbell said he had yet to receive “a proper account from her of what family she had and where they were and how many grandchildren she had”.

Campbell said he was “very conscious” of the possibility that Ieng Thirith was attempting to deceive him, but said he “did not feel that she was deliberately trying to mislead” and was in fact “frustrated by her inability to understand what was going on” during the assessment.