How Does Pregabalin Help?

Pregabalin relieves pain and improves function and quality of life (QOL) for patients with chronic pain due to diabetic peripheral neuropathy (DPN) or postherpetic neuralgia (PHN). But few studies have looked at just why the pain relief and improved QOL go together. Is it because pregabalin has a direct independent effect on patient function and QOL, or are the improvements an indirect consequence of pain relief?