Part Two: The Application of Audio-Visual Entrainment for the Treatment of Seasonal Affective Disorder
By Dave Siever, President of Mind Alive, Inc.
The Captain and Pineal
All species studied to date, from single-celled organisms to humans, have been observed to have a biological clock. This clock is essential for survival, regulating various types and levels of arousal to provide cues for alertness, eating, sleep and the release of hormones. Light waves striking the retina activate electrical output that is sent down the optic nerve to the brain for visual processing. A secondary, smaller nerve tract from the retina, originating from specialized cells that utilize a light detecting pigment called melanopsin, also carries signals to the suprachiasmic nucleus (SCN) of the hypothalamus. The SCN in turn sends nervous outputs to various parts of the brain including the pineal gland. Four genes that govern circadian cycles in flies, mice and humans have been discovered that not only reside within the SCN, but in all cells of the body. When cultured in a petri dish under constant lighting, these cells continue with gene activity, hormone secretion and energy production in a 24-hour cycle that varies less than 1% (Wright, 2002).
In the mid 70s, Dr. Alfred Lewy of the National Institute of Mental Health (NIMH) discovered the neurotransmitter melatonin. The wake/sleep cycle in animals and humans is controlled by melatonin, which is produced by the pineal gland, a structure the size of a pea and located in the mid-brain. Every night, the pineal gland excretes melatonin into the bloodstream and continues to do so until dawn. However, under normal exposure to sunlight, secretions of melatonin follow the Earth’s light/dark time frame and therefore more melatonin is typically released during the long dark hours of the winter months. Henceforth, the pineal gland is in charge or “captains” our wake/sleep arousal states.
Knowing if We Have SAD
Although most anxiety and depression inventories could be used to detect SAD, one popular SAD test is the Seasonal Pattern Assessment Questionaire or SPAQ, developed by Rosenthal and his colleagues at the NIMH. The SPAQ is a self-assessment questionnaire that evaluates one’s level of SAD from four basic categories:
1) Pattern of Seasonality.
2) Degree of Seasonality.
3) The degree that seasonal changes are a problem for you.
4) Evaluating other related information.
SAD and Brain Function
Few PET or SPECT studies of brain metabolism in SAD persons have emerged and they are inconsistent in results. Both Cohen, et al’s, (1992) positron emission tomography (PET) study and a single photon emission computerized tomography (SPECT) study by Murphy, et al. (1993) were inconsistent in results. The results of electroencephalographic (EEG) studies are also inconsistent and involve few electrode sites (Volf & Passynkova, 2002). One such study suggests increased left frontal alpha activity as compared to the right (Allen, et al., 1993), which is consistent with common understandings of depression. Another found all activity except alpha was higher in the left posterior region (Teicher, et al., 1996) while another study showed increased theta-alpha at C3 (Cajochen et al., 1996). Volf sought to finally put the debate to rest by comparing 16 site QEEGs of 31 depressed SAD patients against those of controls. Barring technical issues (a digital filtering concern of aliasing error, possibly invalidating all data, arises within the study), he found asymmetries of delta, theta and alpha involving heightened EEG activity in the right parietal and temporal regions. An asymmetry of heightened beta EEG occurred in lateral frontal regions (F7 & F8).
A number of coping techniques are used to reduce the symptoms of SAD. These include long walks outside, aerobic exercise, a diet rich in complex carbohydrates or “carbs” and protein diets, relocating to sunnier locations, winter vacations to tropical areas, and frequenting sun-tanning centres. Light based clinical interventions include light box therapy and audiovisual entrainment.
“Light box” therapy has been used to reduce the symptoms of SAD in 60% to 80% of SAD patients (Lam, 1999). White light therapy, using intensities of 2,500 lux, requires exposure times from 2 to 6 hours, a considerable behavioral investment for the user (Terman, et. al.,1989). Light exposures in the intensity of 10,000 lux for 30 minute exposures has been found to be more effective than 2,500 lux intensity with exposure times of several hours (Terman, et.al., 1990). Some people have reported that over-use of light therapy can leave them feeling “wired” and restless (Rosenthal, 1993).
Audio-Visual Entrainment (AVE) using flashing lights and pulsing tones has been shown to enhance EEG activity at the stimulation frequency, however, a lesser known attribute of AVE lies in its inhibition effect at roughly the half-frequency of stimulation (Siever, 2003). In QEEGs (brain maps) collected at our office of those with SAD, we have observed long spindles of 10 Hz alpha brain wave activity, globally, with particularly increased activity in the left frontal regions, consistent with Allen’s findings. In light of these findings, we had chosen to utilize 20 Hz AVE as a treatment modality for SAD.
End of Part Two.
Copyright: David Siever, Mind Alive, Inc. for the AVS Journal. All rights reserved.