Going with @Chris W. idea, I came up with this code, although not the finest solution, it works:
<StackPanel>
<!-- With DropShadow -->
<TextBlock Foreground="#FFFF0000" Text="With DropShadow" FontSize="16">
<TextBlock.Effect>
<DropShadowEffect ShadowDepth="0" BlurRadius="1" Color="#FF000000" />
</TextBlock.Effect>
</TextBlock>
<!-- No DropShadow -->
<TextBlock Foreground="#FFFF0000" Text="No DropShadow" FontSize="16" />
</StackPanel>
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…