Plasma met-enkephalin levels: its relationship with age and type of headache.

The aim of the present study was to assess the peripheral proenkephalin-A system in order to determine if it is related in any way to age and/or the type of headache. Our results show no significant change in plasma met-enkephalin (ME) and neutrophil met-enkephalin-containing peptide (NMECP) with aging in controls. Plasma ME levels and NMECP in patients suffering from migraine without aura and tension-type headaches were found to be similar in both groups, younger and older than 60 years old. When ME plasma levels were compared among the three groups of subjects in the two age-groups, only chronic tension-type headache patients differed ( [Formula: see text] ) from both controls and migraine without aura subjects.