What Am I Doing Wrong?

I have been trying to subtract two timestamps from each other to determine
the difference between the two timestamps (current time and a past timestamp
called 'updated_time') IN SECONDS, but no luck.

The trouble I am having is getting the first timestamp, representing the
current time, to translate to seconds; have tried different commands (now(),
localtimestamp, current_timestamp, etc)

What am I doing wrong? Sample statement and error message is below:
                     ------------------------------------------

select EXTRACT(EPOCH from TIMESTAMP current_timestamp) - EXTRACT(EPOCH from
TIMESTAMP updated_time) ::integer

ERROR:  syntax error at or near "current_timestamp" at character 37