function bbp_mention_filter( $content = '' ) {

	// Get Usernames and bail if none exist
	$usernames = bbp_find_mentions( $content );
	if ( empty( $usernames ) ) {
		return $content;
	}

	// Loop through usernames and link to profiles
	foreach ( (array) $usernames as $username ) {

		// Skip if username does not exist or user is not active
		$user = get_user_by( 'slug', $username );
		if ( empty( $user->ID ) || bbp_is_user_inactive( $user->ID ) ) {
			continue;
		}

		// Link
		$profile_url  = bbp_get_user_profile_url( $user->ID );
		$profile_link = sprintf( '<a href="%1$s">@%2$s</a>', esc_url( $profile_url ), esc_html( $username ) );
		$no_followed  = bbp_rel_nofollow( $profile_link );
		$pattern      = "/(@{$username}\b)/";

		// Replace name in content
		$content = preg_replace( $pattern, $no_followed, $content );
	}

	// Return modified content
	return $content;
}