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Bipolar Disorder and Cognitive Impairment

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There’s not a lot that makes you feel better about yourself than someone flat-out telling you you’re stupid.

My doctor seems to think if he gives lots of reasons for my stupidity, excusing me for being a somewhat of an idiot, I’ll feel better about it . It makes me wonder about him.

My family has different technique. They silently acknowledge that well yes, stupid is in there, but they try to make me feel better by pointing out areas where idiocy hasn’t hit. It’s a subtle technique–but I appreciate all efforts.

And all this time I’ve been viewing my befuddlement and lack of acuity as the result of  a  three-pronged attack of ECT (which certainly didn’t help, anyone would acknowledge)–and little was I to know that it was my illness that was sapping IQ points, seemingly while I slept.

My research – which has been handicapped, I must admit, by all the press surrounding Catherine Zeta Jones (you try a good bipolar Google search) – on BD often sticks to the latest news.  But there’s no avoiding this finding.

So breaking news it isn’t. I guess anyone who’s anyone knows that bipolar disorder can be accompanied by mood instability, difficulty getting back to work, a number of comorbidities and. . .cognitive impairment.  Very nice. Very, very nice.

In fact, I thought this was a nice touch. Martinez et al in 2011 start off their piece–first line, no padding, with the following sentence: “Neurocognitive impairment constitutes a core feature of bipolar illness.”

You know–I appreciate when people don’t beat around the bush.

And some points had to be granted. For example, one Dr. Eduard Vieta, of the Department of Psychiatry at the University of Barcelona in Spain, noted that there is impairment in attention, concentration, and memory during both the depressed and manic poles of BD.

Sure enough.

But things were downhill from there.

For there’s been new excitement–not really new at all any more–but at least a decade old–when researchers realized that the impairment displayed by patients during manic and depressive phases, which really aren’t any surprise, carry through into what researchers love to call the ‘euthymic phase,’ which just means, like, ‘normal.’ (I guess if I were really pushed to add something to that it would have to come to not too depressed and not too manic–you know, normal.)

So here we were, starting, I’m guessing, around 2002–and all of a sudden everyone and their brother is researching how, just when you think you’re normal, apparently you’re a few IQ points short of a full deck.  Or, as Martinez-Aran, one of the early researchers on this topic, put it so much more elegantly, “Recent studies have suggested that the presence of persistent cognitive dysfunctions in bipolar patients is not restricted to acute episodes, but they persist even in remission states.”

Okay, okay, he wins in the eloquence contest.  But what’s a little disheartening is that if you go take a look at what the recent research is saying, it seems to be saying the same thing over and over [and how are people still getting grants for this? Do we really need to hear again that BD patients in remission are performing poorly on neuropsychological testing? Can’t they go make some other group look stupid for a while?].

For example, Thompson et al (2005) studied 63 euthymic bipolar patients matched against a control group of the same size. Across the domains tested (e.g. psychomotor performance, attention and executive function), they found that the BD patients were “significantly impaired across a broad range” of domains.  And ultimately they concluded that clinically significant cognitive impairment was found in [get ready for this span] 3-42% of patients.

As a non-statistician, this strikes me as an alarmingly large range–“well, it could be 3 people out of 100–or it could be 42,” doesn’t strike me as completely satisfactory, but perhaps someone can explain it to me.

Bourne et al (2013) analyzed 2876 euthymic bipolar patients using 11 measures from common neuropsychological tests (anyone up on these? They’re truly exciting, as reflected in their names, like Digit Span, or Wisconsin Card Sorting Task.).

Lest there be a moment where we can actually feel good about ourselves, let me tell you that Bourne and his colleagues found impairments for ALL 11 test-measures (and, again, for those big in testing: they controlled for age, for IQ, for gender, etc).  They conclude that the tests are “robust measures of cognitive impairments in bipolar disorder patients.”  Robust, huh? Nothing good can come of that.

 

"Everyone look at their hands. Good. Now hpnotize the warts away on the side with the hand with the 'L'. . . ."

I must admit that for a while I was sulking too much to even go into which area I was impaired in–not just when depressed, I’m reminded, not just when I’m manic, but when I feel fine (not that that happens too much, actually. But apparently when it does, I should still remember that my brain isn’t working right and I’m one card short of a full deck). But Robinson et al (2006) ran a metaanalysis, which I love, because it means they’ve looked through tons of articles–and I don’t have to.

So they–seriously–searched the electronic databases Medline, Embase, Web of Knowledge, and PyschInfo (that should have kept them busy), using these search terms:  bipolar disorder or manic depress⁎, and cognit⁎, attention, learning, memory, executive, or neuropsych⁎ (to identify relevant studies). They then write–and I couldn’t make this up–the search was “limited” to studies available in English (fair enough) and between 1980 and 2005 (that’s not much of a limitation, is it?).

But to get to the point (and it’s a little ‘testy’ here in the language, so hang in there) : They found “strong evidence” of cognitive impairments in executive functioning and verbal learning.  “Large effect sizes were noted for two aspects of executive function” (those were category fluency and mental manipulation), and one of verbal learning.

Only “moderate” effect sizes were found for “indices of short and long delay verbal memory, response inhibition, sustained attention, psychomotor speed, abstraction and set-shifting.”

And as for the “small effect sizes”?  Those were noted for “verbal fluency by letter, immediate memory and sustained attention sensitivity.”

For those of you who weren’t born with neuropsychologists for parents, I’ll do a quick review of what that might mean. “Large” impairment in executive functioning definitely isn’t something you want. Executive functioning is basically a person’s ability to organize. . .his life, pretty much: to prioritize tasks, manage time, make decisions–be a grownup. Category fluency measures verbal memory, and semantic memory,  processing and knowledge. Usually the testee has to say as many words as possible from a given category in 60 seconds–she might have to name fruits, or, say, Ivy League colleges, or baseball players who got nailed for steroids–you get the idea. And in this case ‘mental manipulation’ involved the tester reading as series of number to the poor participant, who is supposed to read them back–backwards. The people who make up these tests must be sadists. Now, for the life of me I could not figure out how verbal learning differed significantly from category fluency (which we’ve had) or verbal memory (which is coming up). I’m quite willing to be educated.

Verbal memory is pretty much what it sounds like, encompassing the memory of language in a variety of forms.  The standard is to ask patients to memorize lists of words or phrases. Response inhibition is another way for saying ‘impulse control,’ and while I was looking this up I ran across Swann et al (2009), who are convinced both that, “Impulsivity is a core component of bipolar disorder, prominent across all phases of the illness” and that abnormal response inhibition is what underlies this increased impulsivity.
So THEY (and I realize I’ve wandered from our original researchers, but when someone has such a strong opinion about my illness it makes me want to sit up and take notice) used the Immediate Memory Task (IMT), which, like all tests that look at impulsivity, requires the participant to selectively respond–or not respond, as appropriate–to target stimuli, presented rapidly.
And how’d the bipolar people do?
They stunk. “Our results confirm that subjects with bipolar disorder were impaired on the [test], with poor discriminability, reduced correct detections (Wilder-Willis et al., 2001), slow reaction times (Fleck et al., 2001; Wilder-Willis et al., 2001), and increased commission errors relative to correct detections (Swann et al., 2003).”
But Swann et al weren’t finished with the negativity.  It isn’t bad enough that bipolar people are over-excitable when they play Space Aliens. Turns out impulsivity in the testing tasks are correlated with (you ready for this?): an “unfavorable course of illness, including multiple episodes, suicide attempts, substance use disorders, and cluster B Axis II personality disorder.” Very nice.
Let’s get back to Robinson and her friends, shall we?
But, to be honest, this is taking far too long–I’ll speed it up. We all know what sustained attention is; psychomotor speed takes the amount of time you require to process information, plan your reaction–and then actually move in response,  After looking extensively into what “abstraction and set-shifting” were and how they were assessed, all I found was about 25 articles on  impairment in abstraction and set shifting in aged rhesus monkeys. I leave you to draw your own conclusions.
To close this definition game down, letter fluency is where the participant has to generate as many words as possible beginning with a given initial letter, immediate memory measures short-term memory.  The tester says a series of numbers–and this time the participant has hit a stroke of luck; she gets to repeat them in the order they were given. This has to do with maintaining attention over long stretches of time.  A commonly used test is the Rapid Visual Information Processing (RVP)–and this will be the one used by the researchers below, who will apparently tell us BD people can’t sustain attention too well (they compare euthymic people to those in a manic state, to schizophrenics–I’ll get there in a minute), where there’s this white box in the middle of a computer screen, a digits from 2-9 (I don’t know what happened to 1, and I can’t find out), appear in random order, 100 digits a minute.  The testee has to find target sequences of digits (like 2-4-6-8-who-do-we-appreciate, sort of thing) and put their responses down in the computer.
Although Robinson and colleagues found  just a small effect in this area, the above-referred-to Clark et al (2002) found a large correlation between BD and sustained attention deficit–and another correlation with the chronicity of the illness. In fact, the researchers went so far as to say that, “[s]ustained attention deficit may represent a neuropsychological vulnerability marker for bipolar disorder.”
So, my friends, there you have it. I’ve never lied to you before, and I won’t start now. It apparently isn’t bad enough to have mood swings, to spend more than three times your ‘up’ time in a deep dark depression, to have perhaps been hospitalized (maybe multiple times), to perchance have given ECT a whirl, to be on meds that make you: gain weight, sleep, think slowly, thirsty, the works–now, it appears, you just might be one card short of a complete deck.

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