Phototherapy

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• Phototherapy
• Nadejda Alekseeva, MD
• PGY-IV Resident
• Department of Psychiatry
• LSUHSC-September 2006

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Light Therapy (LT)

• The least invasive, most natural and effective
  treatment of Seasonal Affective D/O (SAD)
• The original theory behind LT was that it would
  cause a normalization of the phase-shift delay in
  SAD, to lengthen the photoperiod in winter in
  those with SAD and to suppress the production of
  melatonin by the pineal gland

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Seasonal Affective Disorder

• There is much more seasonal difference in higher
  latitudes than in the lower
• In a significant portion of the population of the
  northern US, the shorter days of fall and winter
  precipitate SAD

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Seasonal Affective Disorder

• SAD is a syndrome that can consist of depression,
  fatigue, hypersomnolence, hyperphagia,
  carbohydrate craving, weight gain, and loss of
  libido
• If these symptoms persist in the winter, abate as
  the days grow longer, and disappear in the
  summer, the diagnosis of SAD can be made

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Seasonal Affective Disorder

• Melatonin from the pineal gland has been
  implicated in SAD
• Some individuals with SAD go to the other extreme
  in the spring and summer, experiencing a manic
  state

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Seasonal Affective Disorder

• DSM Criteria for SAD
• -can be applied to the pattern of MD episodes in
  Bipolar I d/o, Bipolar II d/o or MDD recurrent
• -there has been a regular temporal relationship
  between the onset of MD episode (appearance of MD
  episode in winter)
• -full remission or change to mania in spring
• For the last 2 years, 2 SAD episodes

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Epidemiology of SAD

• Incidence of SAD in the general population is
  4-10, with a higher incidence in women than men
• SAD incidence increases in population further
  North
• People from Southern latitudes who move North may
  have an increased risk of SAD
• Some individuals develop a tolerance to seasonal
  changes over time

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Seasonal Affective Disorder

• Decreased exposure to sunlight in the winter
  increases the risk of SAD
• But studies of populations native to Iceland
  discovered a possible genetic adaptation to the
  low light of winter in the arctic
• This population had a SAD prevalence of 1.2
• Another genetic finding SAD occurs more often in
  relatives of those with SAD

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Seasonal Affective Disorder

• The most commonly used SAD diagnostic research
  tools are the
• -Seasonal Pattern Questionnaire (SPAQ)
• -Structured Interview guide for the Hamilton
  Depression rating-Seasonal Affective D/O
  (SIGH-SAD)

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Mechanisms of Seasonal Changes in SAD

• Individuals with SAD have longer periods of
  melatonin synthesis at night in the winter
• Melatonin synthesis is triggered by darkness
• Melatonin synthesis can be suppressed by
  application of LT

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Role of Melatonin

• Melatonin is the immediate downstream metabolite
  of serotonin
• Low brain level of serotonin might contribute to
  SAD symptoms (hyperphagia and carb cravings)
• Increased carb cravings in SAD may be a coping
  mechanism that stimulates the release of serotonin

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Light Therapy

• Is a natural, noninvasive, effective,
  well-researched method of treatment for SAD
• Various Light temperatures and times of
  administration of LT have been studied
• Combination of morning and evening exposure
  appears to offer the best efficacy

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Light Therapy

• Been used to suppress the production of melatonin
  by the pineal gland
• Light enters the retina, which in turn stimulates
  the suprachiasmatic nucleus of the hypothalamus
• This in turn inhibits the pineal gland from
  converting serotonin to melatonin

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• What are the 4 components of bright light therapy?

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• The 4 components of bright light therapy are
• Intensity
• Timing
• Duration
• Wavelength

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• What light intensity is necessary for melatonin
  suppression?

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• Light intensity greater than 2000 lux is
  necessary for melatonin suppression in most people

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• What is the recommended use of bright light box
  in SAD?

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• Exposure to the eyes of diffuse visible light
  with an intensity of at least 2500 lux daily,
  preferably in AM, for at least 2 h
• Most light boxes produce 2500 lux at a distance
  of 3 feet, and light intensity is inversely
  related to the square root of distance of the
  eyes to the light source

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• Using the 2500 lux box at 1.5 feet from the eyes
  produces 10,000 lux, and the duration of
  treatment can be reduced, as 30 min at 10,000 lux
  is equivalent to 2 h at 2500

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• How long does it take to show a response to
  bright light?

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• Response to bright light therapy usually begins
  within 3 to 4 days, with full response in 1 to 2
  weeks
• when LT stopped, relapse can occur in 3 to 4 days

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Light Therapy

• Has an overall positive treatment response of up
  to 70, with rarely any side effects

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• Combination of LT and CBT demonstrated a lower
  remission rate than LT alone

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Light Therapy

• Experimental treatment extended to other
  conditions
• Non-seasonal mood d/o
• Alzheimers disease
• Circadian-related sleep d/o
• Jet lag
• Eating d/o

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• LT improves nocturnal sleep in people with
  dementia
• LT reverse age-associated disturbances of
  circadian sleep-wake rhythm
• LT prevent the age-associated decrease in the
  number of vasopressin-secreting neurons in the
  suprachiasmic nuclei of the hypothalamus

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• Despite the growth in clinical and research
  programs, there is an absence of recognition and
  support for LT
• Most insurers do not pay for this treatment
• Most residency training programs do not provide
  training in Light Therapy