The Application of Audio-Visual Entrainment for the Treatment of
Seasonal Affective Disorder: Part 2
By Dave Siever
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).
Copyright: Dave Siever (2013) CA. Reprinted with permission. All rights reserved.