The purpose of this longitudinal exploratory prospective study is to investigate the brain changes in the development of chronic low back pain.

Background and Purpose: Chronic low back pain (cLBP) is an adverse symptom not only to individuals but also to society. It impacts negatively on multiple aspects, such as physical activities, functional ability, quality of life and psychological status. Moreover, cLBP causes economic burden to both individuals and society. However, not all low back pain progresses to chronic condition. Cross-sectional studies have shown brain activated differently in people with cLBP as compared with healthy ones during rest and movement. In addition, lower cortical excitability or stronger functional connections between medial prefrontal cortex and nucleus accumbens were observed in those becoming cLBP according to previous longitudinal studies. Also, image studies have shown a shift in brain regions from pain related areas to those that control emotion and memory. According to these results, the brain activity is related to the persistence of pain. However, how brain activity changes during the chronicity of low back pain is still not fully understood. Therefore, the purpose of present study is to compare the brain changes in people with LBP with or without pain chronicity.

Methods: This is a longitudinal exploratory prospective study. Demographic data will be collected at baseline. The outcomes will be measured at entry of the study and at 24 weeks post-pain. Outcomes include pain intensity which is rated by Numerical rating scale(NRS), and brain activities which is recorded by electroencephalography (EEG) during resting and movement conditions.

Statistical analysis: According to the NRS at 6 month post-pain, the participants whose NRS sore ≥ 2 will be grouped in the cLBP group and those NRS ≤ 1 will be grouped in the recovered low back pain (rLBP) group. Two-way ANOVA with repeated-measures and Tukey's post hoc test will be used to analyze the differences between time and between groups. The changes of pain intensity during movement will be used as confounder for the analysis. Statistical significance is set at p<0.05.

Inclusion Criteria:

• Age≧ 20 y/o
• This is the 1st episode of low back pain in the past year
• Pain in the region of the lower back (bound by the thoracolumbar junction superiorly, and by the gluteal fold inferiorly)
• Pain duration < 12 weeks
• Average pain intensity in the past 7 days is ≧ 3/10 (Numeric Rating Scale)
• Mini-Mental State Examination ≧ 24

Exclusion Criteria:

• Pain onset duration < 7 days
• History of chronic pain
• Pain area other than the specify area
• Any systematic disease, fracture or cancer
• Present any neurological sign related to pain
• Infection
• Received any brain or spine surgeries, hip arthroplasty or any other kind of surgeries in the past 3 months
• Diagnosed with any neurological or psychological disease

Population from community and local clinics will be selected.