‘In the dark time of the year…
The soul’s sap quivers.’
TS Eliot, ‘Little
Gidding’
For many of us, as the dark descends so does our mood. I’ve
never understood why ‘SAD’, to some people at least, has been a controversial
diagnosis. Compared to a lot of nonsense in the DSM, the diagnosis of SAD as ‘recurrent
major depressive episodes with a seasonal pattern’ seems to just to be what
it says on the tin.
Who
gets it?
In
the UK 6% of adults suffer from SAD but many more, perhaps most of
us, get a milder form of ‘winter blues’.
It tends to come on in early adulthood, but can occur in children, and women
are more often affected.
How does it present?
People of course rarely come in and say I have ‘SAD’. But
people with SAD consult us much more than
matched control groups with non-specific symptoms.
As well as the typical symptoms of depression it presents with atypical
(‘hibernation-like’) symptoms such as hyper-somnolence, carbohydrate craving
and weight gain. The symptoms of SAD
often resonate with seasonal changes seen elsewhere in the animal world. Top of
my list of ‘research papers I never get time to write’ is that it is my
impression that ‘tired all the time’ consultations become more frequent once
the darkness descends.
What causes SAD?
Serotonin
metabolism has a seasonal pattern and melatonin metabolism is also thought to
play a role. Melatonin secretion is stimulated by darkness and suppressed by
light. Failure to switch off melatonin, which may have a genetic component, has
been implicated as a cause. This may be linked to seasonal changes seen elsewhere
in the animal world. Even algae demonstrate seasonal changes in behaviour, and
some evolutionary biologists have suggested SAD may be a reflection of an
energy-conserving hibernation like state which is adaptive. Some papers have
found an association (no surprise) with Vitamin D deficiency, but there is no convincing
evidence that Vitamin D supplementation prevents it.
How
should we diagnose it?
As with everything in general practice, awareness and an open
mind is key. It is worth asking about
seasonal changes in mood and behaviour in people presenting not just with
depression but with ‘tired all the time’, hyper-somnolence and ‘I just feel run
down doctor’ in the winter months.
What
treatments are proven to work?
- Light therapy
·
It
is thought that morning light therapy might suppress excess melatonin secretion
and influence serotonin metabolism. A
systematic review of RCTs of bright light therapy for SAD comparing at least
3,000 lux-hours daily compared to a
control of just 300 lux showed persistently positive outcome for the light
therapy
·
This
‘light therapy’ usually consists of no more than sitting 2 or 3 feet away from
a bright light ‘box’ on a table, you can read/work at the same time, for 30-60
minutes a day. A ‘dawn simulator’ light
is an alternative strategy.
·
SAD lights cannot be prescribed on the NHS, but
if patients have SAD they do not have to pay VAT i.e. a 20% discount.
o
Antidepressants
·
There
is a lack of good quality evidence, but there is some RCT evidence for fluoxetine. For selected patients,
these may just be taken in autumn and winter (NB anecdotally I have a number of
patients who find it very helpful to start them when the clocks go back and
then tail off when the clocks spring forward again)
· For colleagues in the US, there is good evidence
for buproprion (Wellbutrin XL) as a
preventive strategy
A recent BMJ review of the evidence (below)
concluded: ‘Using a light box or dawn simulation
appears to be a reasonable first-line approach to relieve mild or moderate
depressive symptoms instead of, or as well as, drug therapy and/or CBT.
Patients with more severe symptoms should be treated with antidepressant drugs
with or without light therapy and/or CBT’
Self-help.
There is a lack of evidence
for exercise, but anecdotally it definitely seems to help! NHS direct has a useful self-help leaflet for
SAD and also for ‘winter blues’ recommending exercise, diet and exposure to
natural light (see below)
Conclusion
Be aware of SAD and
Winter Blues in patients presenting not just with low mood, but also ‘tired all
the time’, hyper-somnolence and general malaise. For simple ‘Winter Blues’
advise lifestyle changes and consideration of light therapy. For established
SAD consider light therapy, seasonal SSRIs and CBT. There is no convincing
evidence for Vitamin D, but given there is an association with Vitamin D
deficiency supplementation may be worthwhile.
Resources for
patients:
o Great
book, but quite detailed!
o Very
useful web-pages
o Information
on light therapy
http://www.lumie.com/ (NB this company offer a free 30 day trial;
if its going to work it should be by then! No conflict of interest here.)
References:
SAD
was reviewed in the BMJ 2010:340:c2135
o
The
SAD association www.sada.org.uk
has useful information on how to do it, manufacturers and costs of lights etc.)
