UNITED NATIONS — When the World Health Organization wanted to know how the war in Syria was affecting the mental health of those forced to flee their homes, the agency hired someone known less for her expertise than for her connections: The consultant, Shukria Mekdad, is the wife of Faisal Mekdad, the deputy foreign minister of Syria and a powerful defender of the government’s war effort.

Her appointment has led critics to question the aid agency’s impartiality.

Jennifer Leaning, a professor at the Harvard T. H. Chan School of Public Health, questioned what she called the “optics” of hiring a senior Syrian government official’s wife as a consultant on something as sensitive as mental health. Not least, Ms. Leaning said, it would call into question any data Mrs. Mekdad gathers on the mental health of Syrians displaced by a war her husband has helped prosecute.

“At this point it reflects a degree of tone-deafness that is not appropriate,” Ms. Leaning said.

The W.H.O. chief in Damascus, Elizabeth Hoff, defended the choice, saying that her team includes people from all political camps. “I didn’t recruit them based on their names or their connections,” Ms. Hoff said. “I also have people in my office who are strongly with the opposition.”

Mrs. Mekdad, she went on, plays no “prominent” role in the office, and was brought on as a consultant for the mental health assessment project after she had served in the United Nations resident representative’s office in Syria.