|
What causes the seasonal
symptoms of bipolar disorder?
"We don't really know what causes
it," says Dr Anthony Levitt. "There are many theories,
some of which are very compelling. But there's
clearly an interplay between three things":
1) Biological disposition
"There's something in the patient's genetic makeup
that makes them susceptible to seasonal changes.
There could be a genetic disturbance to the clock
genes which regulate circadian rhythms."
2) Environmental triggers
"This means big things, not what direction the
wind is in, but some sort of geoclimatic variable
— day length and exposure to light, rate
of change in day length, barometric and temperature
changes."
3) Thermal comfort "Everyone's
got their own personal reaction to weather. I'm
from Australia where we basically only have two
seasons, wet and dry. I just met someone from
Australia who's been in Canada just a couple of
months. He asked me, 'How am I ever going to get
used to Canadian winters?' That's exactly the
way I felt when I first arrived, but I adapted,
but still if there's a slight chill in September
I have my hat and mittens on. The thermal comfort
of people with bipolar disorder is likely set
at a fairly intolerant level, and they don't adapt
well to changes in temperature, etc."
Northern spike? Since
there appears to be a daylight component, one
would think seasonality would be more prevalent
in countries like Canada which have shorter days
in the winter and longer days in the summer. Not
so, says Dr Levitt. "We did a study that looked
at latitudes in Ontario and we found there was
no change, he says. "Actually, the difficulty
improves the further north you go, probably because
people who can't cope move south. There have been
studies that have compared say Finland to Florida
and found more [cases] in Finland — but ours
was the only one to actually look at latitudes
and what we found was the opposite to what everyone
expected."
Some places are better than
others, however. "At the equator, where there
are no seasons, there's no seasonality. We found
that at 43-44° it's at its peak, where there
are four seasons."
|
"April is the cruellest month,"
wrote T S Eliot in his modernist masterpiece The Waste
Land. For bipolar disorder (BP) patients with seasonal
symptoms, he had it exactly right. Springtime is the high
season for manic episodes in these patients, though nobody's
exactly sure why.
"The admission peak in Ontario
is April for mania," confirms Dr Anthony Levitt, psychiatrist
in chief at Sunnybrook and Women's in Toronto. "In fact,
this week was exceedingly busy for my emergency colleagues
here at Sunnybrook." Many patients go straight from
winter depression to spring mania.
Although some of the symptoms feel
good, most are as debilitating as depressive symptoms.
"Mania is a very unhappy, disruptive experience," says
Dr Levitt. "Patients may feel elated, high or abnormally
happy, energetic, but they may also feel intensely irritable,
be extremely talkative, have an inflated sense of self-worth
and have grandiose ideas."
All of this can tailspin out of
control. "They can behave dangerously — speeding,
overspending, taking drugs, engaging in dangerous sex.
They're often not sleeping and not feeling tired," he
says. Some of the time they're feeling really good during
a manic episode, but "there are brief moments of lucidity
where the patient realizes what's going on and they'll
often seek help."
THE
CHAOS CYCLE
Dr Levitt is one of Canada's few experts on seasonality
and BP. He says while seasonal depression is well-known,
within BP seasonal symptoms often get muddled up with
other cycling the patient experiences. "Symptoms are
entrained in cycles," he explains. "Some people have
diurnal changes — changes across the day —
typically down in the morning and high in the evening.
Others, especially women, have monthly changes that
tag on to their menstrual cycles. Then there are those
who have weekly and annual cycles."
"But these can combine," says Dr
Levitt. "I have a patient we discovered had daily cycles
superimposed on annual seasonal cycles. So in the winter
he would be even lower in the mornings and in summer
he'd be even higher in the evenings."
To the treating physician, this
can seem like complete chaos. "Patients like these seem
impossibly unstable," says Dr Levitt. "That's where
you get what we call 'therapeutic nihilism' — where
it just seems too complicated."
FOOL
ME ONCE...
All of this makes the symptoms extremely difficult to
treat. "For example, someone will feel high so the treating
physician will give them something to bring them down
— it might seem to work, but it had nothing to
do with the drug. They actually spontaneously recovered
because the seasonal symptom passed," explains Dr Levitt.
"But the physician thinks it was the drug so they'll
keep the patient on it indefinitely. The danger is we
can actually be making the condition worse."
Dr Verinder Sharma, a psychiatrist
at the Mood Disorders Unit at the University of Western
Ontario, says he's seeing a lot of BP patients misdiagnosed
with seasonal affective disorder (SAD) by both family
physicians and psychiatrists. "They're given antidepressants
for SAD and this worked initially and then there's a
relapse in spite of continued treatment," he explains.
"These patients had hypomatic symptoms that weren't
picked up. I think what was happening is they were focusing
on the seasonal depression and not looking at family
history."
This can lead not only to missed
treatment opportunities, but worsening of symptoms.
"Antidepressants can definitely also bring on mania,"
he says. "We're seeing more of this."
DEAR
DIARY
So what's a physician to do? First of all, try to establish
whether or not the patient has seasonal BP, although
this can be extremely difficult when other cycling is
involved. "You can do this by observation, careful history
taking, input from family," he adds. Both Dr Levitt
and Dr Sharma swear by mood diaries. "I encourage patients
to keep a mood diary," says Dr Levitt. "We find mood
diaries very useful," agrees Dr Sharma. "Some patients
will say to me, 'Look, this is happening to me every
winter.' But when most patients present with depression,
it affects what they report, so it's better to do a
longitudinal recording of their moods." The diary allows
the physician to track changes in their symptoms over
time — to put the whole thing in context and get
the big picture. Making out the patterns isn't easy,
though. "The pattern can be very subtle, changing daily
and yearly," notes Dr Levitt. "It's very time-consuming."
When a physician has established
the patient has seasonal BP, they can try to work out
a medication schedule that follows their symptom patterns.
"You can adjust the treatment, prescribe light therapy
in the winter and increase the anti-manic medication
in the summer," says Dr Levitt. For instance, for his
patient who has diurnal cycling and annual seasonal
symptoms, he's worked out a regimen where the patient
gets a mood stabilizer in the winter and an anti-epileptic
in the summer.
"It's very challenging to treat,"
says Dr Sharma. "There are some patients who may require
a slightly higher dose of the medication they're using."
"This is not commonly done by psychiatrists
— very few look at seasonal fluctuations," notes
Dr Levitt. "I'm speaking from the lofty vantage point
of someone who's interested in this. Very few people
get managed properly."
|
