Ian Bush appeared in an Ottawa court on Wednesday following his arrest last week.
Bush will return to court Jan. 23 after the court-ordered assessment determines whether he could be held criminally responsible for the charges against him.
Ernest Cote, 101, had been tied up in his home and robbed by a man posing as a city employee last week.
The attack prompted widespread outrage, including that of Veterans Affairs Minister Julian Fantino.
Cote is a D-Day veteran who landed on Juno Beach on June 6, 1944 and Fantino had travelled with him earlier this year for commemoration ceremonies in France.
Police had said Cote was alone in his apartment when a man claiming to work for the city asked to be buzzed in.
The phoney employee went to the apartment and asked for money at the door, then forced his way inside when his demands weren't met.
Police said the intruder bound the man and took undisclosed items from the apartment.
Cote later managed to free himself and call police.
Bush has been charged with attempted murder, robbery with violence, forcible confinement, break and enter, and using a credit card obtained by crime.
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