HALIFAX—Former federal NDP leader Alexa McDonough, a political trailblazer who paved the way for women in politics, died Saturday in Halifax at the age of 77. Her family confirmed McDonough’s death after a lengthy struggle with Alzheimer’s disease. McDonough became the first woman to head up a major political party in Canada when she was elected leader of the Nova Scotia New Democrats in 1980. She became leader of the federal NDP in 1995 and served in the party’s top post until 2002. But in an interview Saturday, Justin McDonough said his mother was a consensus builder who earned respect beyond partisan political lines. “I think the one thing that I really learned from her is that you can have courageous conversations and you can disagree with someone, but it doesn’t mean that you aren’t going to be respectful and you’re not going to appreciate their opinion,” he said. “Her …