1.
To drag someone down means to reduce them to an inferior social status or to lower standards of behaviour.
She dragged him down with her...
There were fears he would be dragged down by the scandal.
PHRASAL VERB: V n P (not pron), be V-ed P by n
2.
Something that drags you down makes you feel weak or depressed.
I have had really bad bouts of flu that have really dragged me down.
PHRASAL VERB: V n P