A major reason for the substantial underuse of pharmacological prevention of migraine is its inadequate efficacy, since only ~50% of patients respond to a specific agent. There is currently no evidence-based way to identify the patients that will respond to a specific preventive treatment. Amitriptyline is one of the commonest agents used for migraine prevention, strengthening patient's pain inhibitory capacity. Individual tailoring of analgesics according to pain inhibitory capacity has been shown effective by our group for painful diabetic neuropathy patients. Specifically, patients with reduced pain inhibition capacity gained more from a drug that augment pain inhibition as compared to those with efficient inhibitory capacity. The investigators now propose to assess migraineurs for their pain inhibition capacity, and examine whether, along similar reasoning, those with reduced inhibitory capacity are the ones more likely to respond to amitriptyline. Psychophysical and neurophysiological dimensions of pain inhibitory modulation will be assessed in migraineurs, who will, subsequently, receive either amitriptyline or placebo for 8 weeks, in a randomized two arms parallel double blind design, and followed up for attacks reduction. The investigators expect to identify the best predictors for efficacy of migraine prevention by the study drug. This approach will promote individualization of migraine therapy.

Inclusion Criteria:

• age >18
• premenopausal
• meeting the international headache society criteria for migraine
• having >4 attacks or days of migraine/month

Exclusion Criteria:

• baseline month diary indicating lower frequency of migraine
• chronic migraine (>15 days of headache per month)
• use of migraine preventive treatment during previous 3 month
• language barrier or cognitive dysfunction