Vol. 16, #3

Acupuncture And Cognitive Function:
An Audio-Evoked Potential P300 Study
Orawan Silpakit, MD
Chatchawan Silpakit, MD

ABSTRACT
Background Audio-evoked potential is a technique used for measuring brain functions such as memory, attention, and concentration. To date, there may be no study using audio-evoked potential to test the effect of acupuncture on cognitive function.
Objective To investigate the efficacy of acupuncture of Sishencong (Ex-Hn1) acupoints on attention and concentration.
Design, Setting, and Patients An experimental study in May 2003 of 14 volunteers (6 men and 8 women; mean [SD] age, 40 [8] years) in Thailand. All participants were hospital staff.
Intervention Patients received 10 total acupuncture treatments at Sishencong 2-5 times weekly. An audio-evoked potential P300 (EP300) was recorded at baseline within 1 day after therapy and at 1-week follow-up.
Main Outcomes Latency time and amplitude of EP300 at the central point were analyzed. Patients self-rated sleep, concentration, and emotion with a Likert scale within 24 hours of treatment at baseline, after the 3rd, 6th, and 10th times, and at 1-week follow-up.
Results The latency time was decreased, but not significantly (P=.20). Self-rating for sleep (P=.31) and concentration (P=.31) were not statistically significantly different. However, all participants reported that they felt sleepy earlier at night and slept more restfully than previously. Participants' rating of mood was improved, albeit not significantly (P=.07).
Conclusion Our results demonstrate a trend toward efficacy of acupoint Sishencong via EP300. Further study in this area should be conducted.
KEY WORDS
Acupuncture, Cognitive Function, Evoked Potential P300, Attention, Sleep

INTRODUCTION
Acupuncture is accepted as an effective treatment for many symptoms and disorders, including neuropsychiatric disorders.1 The number of patients choosing acupuncture as an alternative treatment is increasingly parallel to growing scientific evidence supporting the efficacy of acupuncture. Scientific studies of acupuncture are mostly related to pain treatment, but more and more are being conducted in other areas. Studies confirming the efficacy of Hegu and other acupoints for pain relief have been confirmed by somato-evoked potential techniques.2-6 A popular acupoint for mental and nervous system diseases is Baihui; additional acupoints include Sishencong (Ex-HN1), which would enhance the efficacy of Baihui.7

Audio-evoked potential is a technique used for measuring brain functions such as memory, attention, and concentration. An audio-evoked potential P300 (EP300) measures physiologic changes of brain function according to stimulus at about 300 milliseconds.8 This late event potential reflects attention or concentration, one of the cognitive functions of the cerebral cortex.9 In general, normal latency time range is 265-500 milliseconds.10
 There are many studies of EP300 in Parkinson disease, depression, schizophrenia, and dementia.10-16 One study reported latency time was related to regional cerebral blood circulation.14 EP300 has been used to measure the progression of Alzheimer disease.16 There is no study using audio-evoked potential to test the effect of acupuncture on cognitive function. To test the efficacy of acupuncture on cognitive function, we applied audio-evoked potential (EP300) as an outcome measurement.

METHODS
This study was conducted in May 2003. All participants signed a consent form; the project was approved by the hospital ethics committee.

Participants were required to read English and refrain from using anxiolytics, antidepressants, antiepileptic drugs, sleeping pills, cold-relief pills, b-blocker agents, bronchodilators, opiate-related analgesic drugs, and warfarin 4 weeks before enrolling in the study. Patients received acupuncture 2-5 times a week for a total course of 10 treatments. EP300 was recorded at baseline, after completing acupuncture, and at 1-week follow-up. Patients were asked to rate their sleep, concentration, and mood on a 0-5 Likert scale.

EP300 Record
Electrodes were pasted on the participant's scalp by gel or tape at the central point and mastoid areas. Participants were asked to listen to sound stimuli through headphones at 80-dB intensity. The frequency of background sound was 1000 Hz and was stimulated at a rate of 1.1 per second for 300 times. They were asked to count the click sounds at 1500 Hz, which were randomly produced. The EP300 was recorded by the Bio-Logic instrument. The amplitude and latency time of P300 at the central point were calculated. P300 was identified by a highest positive wave immediately followed by the 2nd negative wave. Participants were asked to listen to stimuli in each ear and in both ears. The average time of recording was 18 minutes.

Acupuncture
Participants received acupuncture at Sishencong. Hwato disposable needles (diameter, 0.25 mm and length, 0.13-0.25 mm) were inserted horizontally with 1-1.5 cm depth and retained for 30 minutes. Sishencong is composed of 4 acupoints located 1 cun anterior, posterior to, and on both sides of Baihui, which is located directly above the apex auricles on the midline of the head. Participants had to report needling sensation at acupoints (De Qi). If any pain occurred, the researcher adjusted the needle position.

Statistical Analysis
Means and standard deviations were calculated. The difference of means was analyzed by a nonparametric repeated-measure test (Friedman test).

Table 1. Amplitude and Latency Time Outcomes

 

Amplitude, mV

Latency Time, ms

Measurement

1*

2†

3‡

1*

2†

3‡

Mean

8.4

7.7

6.8

315.1

301.1

305.3

(SD)

-3.4

-4

-3.7

-53.4

-46.7

-51.9

Range

3.7-14.9

2.7-15.7

1.8-15. 7

252-414

252-370

255-410

*Baseline values. †After completion of acupuncture course. ‡At 1-week follow-up.



Table 2. Self-rating Outcomes

 

Baseline

Visit 2

Visit 3

Visit 4

Mean Follow-up*

x2

P Value

Sleep

2.93

2.86

2.68

2.93

3.61

4.75

0.31

Concentration

2.5

3.32

3.14

2.96

3

4.81

0.31

Affect

2.64

3.21

2.82

2.96

3.3

8.59

0.07

*After the 3rd, 6th, 10th and 1 week's time following acupuncture.


RESULTS
Fourteen volunteers, 6 men and 8 women, were recruited (mean [SD] age, 40 [8] years). All were staff workers in a hospital in Thailand. Table 1 shows the results of latency time, which tended to decrease over time while amplitude tended to increase. However, these changes were not statistically different (x2 = 3.23, P = .20 and x2 = 4.14, P = .13 for latency time and amplitude, respectively).

Pre- and post-intervention and self-rating for sleep and concentration were not statistically significantly different (x2 = 4.75, P = .31 and x2 = 4.81, P = .31) (Table 2). Yet participants' rating on mood was improved (x2 = 8.59, P= .07). All participants reported that they felt sleepy earlier at night and slept more restfully than before.

DISCUSSION
The latency time of EP300 was not statistically significantly different before and after needling. However, all participants reported improvement in their quality of sleep. This might be explained by the small sample size and the short study time. We were unable to recruit participants of the same age group.

Age and intelligence have important effects on latency time.8 Apart from these, the technique of EP300 record had to be improved. The recording time was too long and some participants' attention waned and sleep occurred; the research assistant had to awaken them and this may have interfered with the results. To replicate and expand on our findings, the study time of acupuncture and the number of cases need to be larger.

CONCLUSION
The efficacy of acupuncture on cognition measured by EP300 was not statistically different although there was an important trend. The technique of recording should be improved. Binaural stimulation is recommended for recording and analysis. Proper case selection and the course of acupuncture should be considered.

ACKNOWLEDGEMENT
This study was funded by the Srithanya Hospital fund, and we are grateful to the hospital director for his support.

REFERENCES

  1. Thai Acupuncture Association. http://www.thaiacupuncture.org/healine/ indication.shtml. Accessed July 29, 2003.
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  9. Delis D, Squire L, Gainotti G, eds. Neuropsychological assessment of learning and memory. In: Handbook of Neuropsychology. Oxford, United Kingdom: Elsevier Publishing; 1989.
  10. Blackwood DH, Whalley LJ, Christie JE, Blackburn IM, St Clair DM, McInnes A. Changes in auditory P3 event-related potential in schizophrenia and depression. Br J Psychiatry. 1987;150:154-160.
  11. Gil R, Neau JP, Toullat G, Rivasseau-Jonveaux T, Lefevre JP. Parkinson disease and cognitive evoked potentials. Rev Neurol (Paris). 1989;145:201-207.
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  14. Mochizuki Y, Oishi M, Takasu T. Correlations between P300 components and regional cerebral blood flows. J Clin Neurosci. 2001;8:407-410.
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AUTHORS' INFORMATION
Dr Orawan Silpakit is a physician at Srithanya Hospital, Dept of Mental Health, in Nonthaburi, Thailand.

Orawan Silpakit,MD*
Srithanya Hospital, Tivanont Rd
Nonthaburi 11000, Thailand
Phone: 66-91254673
Fax: 66-25254091
E-mail: osilpakit@hotmail.com

Dr Chatchawan Silpakit is a physician at Ramathibodi Hospital, Dept of Psychiatry, Faculty of Medicine, in Bangkok, Thailand.

Chatchawan Silpakit, MD, PhD
Faculty of Medicine
Ramathibodi Hospital, Dept of Psychiatry
Rajathevi, Rama 6
Bangkok 10400, Thailand
Phone: 66-96853110 • Fax: 66-22459647
E-mail: racsp@mahidol.ac.th

*Correspondence and reprint requests

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