Amin made 8 of 11 field goals, including 2 of 4 from 3-point range, and had three steals.
Hameed Ali had 13 points, a career-high 12 rebounds and five steals for the Islanders (14-3, 5-0 Southland Conference), who have won seven games in a row and 14 of their last 15. Brandon Pye scored 17, including three 3s, and Joe Kilgore added 12 points, seven rebounds and four blocked shots.
A 3-pointer by Sabri Thompson pulled Northwestern State (3-13, 0-6) within 33-31 with 3:53 left in the first half, but the Islanders scored eight of the next 10 points and took a 44-35 lead into the break.
Amin's layup with 15:31 to play capped a 9-0 run and made it 53-38 and Northwestern State trailed by at least seven from there.
Ishmael Lane led the Demons with 18 points and 11 rebounds.