VBA Alt + Down Macro

Jeremy1565 Assuming you are using a selection_change event, you could test the target range to see if it has an in cell dropdown (%{DOWN} causes my number and caps locks to toggle, but %{UP} appears to work okay) - it should work for any cell on the worksheet. 

If you wanted to restrict it to specific columns, you could add another test to intersect target with those ranges (say columns E, G, and I):

If Intersect(Target, Me.Range("E:E, G:G, I:I")) Is Nothing Then Exit Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
     
     On Error GoTo ErrHandler
     If Target.Cells.CountLarge > 1 Then Exit Sub
     
     If Target.Validation.InCellDropdown Then
          Application.SendKeys "%{UP}"
     End If
 
ExitProc:
     Exit Sub
     
ErrHandler:
     Resume ExitProc
     
End Sub