Is there a way to fetch associative array grouped by the values of a specified column with PDO?

For example, let's use some simple data set

+---------+------+------+------------+
| name    | age  | sex  | position   |
+---------+------+------+------------+
| Antony  |   34 | M    | programmer |
| Sally   |   30 | F    | manager    |
| Matthew |   28 | M    | designer   |
+---------+------+------+------------+

What we are trying to get is array organized this way

Array
(
  [Antony] => Array
    (
      [age] => 34
      [sex] => M
      [position] => programmer
    )

  [Sally] => Array
    (
      [age] => 30
      [sex] => F
      [position] => manager
    )

  [Matthew] => Array
    (
      [age] => 28
      [sex] => M
      [position] => designer
    )
)

As a rough approximation we can use

$pdo->query('SELECT * FROM employee')->fetchAll(PDO::FETCH_GROUP|PDO::FETCH_ASSOC);

But as result we have unnecessary nesting level

Array
(
    [Antony] => Array
        (
            [0] => Array
                (
                    [age] => 34
                    [sex] => M
                    [position] => programmer
                )

        )

    [Sally] => Array
        (
            [0] => Array
                (
                    [age] => 30
                    [sex] => F
                    [position] => manager
                )

        )

    [Matthew] => Array
        (
            [0] => Array
                (
                    [age] => 28
                    [sex] => M
                    [position] => designer
                )

        )

)

I tried to get rid of this unnecessary nesting level by using callback function

$stmt->fetchAll(PDO::FETCH_GROUP|PDO::FETCH_ASSOC|PDO::FETCH_FUNC, 'current');

But for some reasons It passes not

Array
  (
   [0] => Array
    (