Aldridge thinks Jordan Henderson's injury problems this season could leave a void in the side.
Henderson has struggled with a heel problem for much of the season, and has had to contend with a broken metatarsal as well.
Having made a return to action in late November, the heel problem has resurfaced and Aldridge doesn't think there is the type of midfielder within the Reds' side that can fill the void left by the skipper.
The ex-striker wrote in his Liverpool Echo column: "I'd like to see him move in the market in January if there's a player of real significance he thinks he can go and get. Someone with a presence, a leader.
"What's the priority? You could say all departments need strengthening but if Jordan Henderson is going to be out for a while again then I'd say signing a centre midfielder is the key.
"When he's not there, we miss Henderson's energy and his dynamism. You don't really get that with [Emre] Can, Lucas or [Joe] Allen.
"We need a strong centre midfielder – someone with a massive presence who can get from box to box."
There has certainly been the question of leadership, or lack of it, in the Liverpool squad this season, so that point is valid when Henderson's either injured or fit.
In terms of the midfielder's at Liverpool's disposal, no other central player seems to put themselves about as much as the Liverpool captain. He covers a lot of ground, helps out at the back, has a pretty good first time ball and can provide a goalscoring threat. Emre Can is probably the closest Liverpool have got to that but he seems so raw, meaning the Reds would be looking for someone around the same age.
Jurgen Klopp also has James Milner at his disposal but he probably prefers him to play a little wider than Henderson and tuck in at times to help the midfield out, rather than operate in the same way as Henderson.