Depression's Cognitive Downside

Author and blogger Jonah Lehrer has a lengthy (and controversial) essay in the Feb. 28 New York Times Magazine on Depression's Upside. The main idea, that depression has cognitive and evolutionary advantages, was largely based on a review paper by Andrews and Thomson (2009). In it, they put forth the analytical rumination hypothesis: depression is an evolved response to complex problems, and focusing on them to the exclusion of everything else is beneficial. Lehrer's piece generated an outpouring of comments (both pro and con), questions, and critiques. One notably critical rejoinder (The Myth of Depression’s Upside) was written by Dr. Ronald Pies, the Editor in Chief of Psychiatric Times:

Now, with all due respect to Dr. Thomson, I am inclined to ask, “[Insights gained during depression are] worth it to whom?” Perhaps the patients Dr. Thomson has treated emerge from their three-month bouts of depression saying, “Ya know what, Doc? It’s been a bad three months—lost my job, almost killed myself, and couldn’t get a damn thing done—but overall, it was worth it!” The depressed patients I evaluated over the past nearly 30 years almost never reported that their major depressive episodes had a “net mental benefit,” to quote Lehrer’s article. Most felt that their lives and souls had been stolen from them for the duration of their depressive episode.

In other words, Dr. Pies's patients don't feel like they've solved all their problems. Most of the studies cited in favor of improved problem-solving abilities involved a sad "mood induction" procedure such as watching a 10 min film showing a death from cancer or being given false negative feedback on cognitive test performance (Forgas, 2007). It should be obvious that a transient, slightly sad state is drastically different from a prolonged major depressive episode. Jonah does acknowledge this in his article, but the distinction appears to undermine Andrews and Thomson's entire basis for asserting analytical advantages for the depressed ruminator. It's another in a long line of evo psych just-so stories.

The literature is filled with papers describing the cognitive impairments associated with major depression. Jonah recognizes this as well, but then overstates how easy it is to dispense with the deficits:

The end result is poor performance on tests for memory and executive function, especially when the task involves lots of information. (These deficits disappear when test subjects are first distracted from their depression and thus better able to focus on the exercise.)

On the contrary, numerous papers have shown that impairments in cognitive processes such as executive control, attention, and memory persist after a depressed person has recovered (Andersson et al., 2010; Baune et al., 2010; Hammar et al., 2009). In actively depressed patients, Baune and colleagues (2010) found impairments in all domains tested: immediate memory, visuospatial construction, language, attention, and delayed memory. These deficits can contribute to lower social and occupational functioning and a diminished quality of life. In addition, depression can be associated with declines in problem solving abilities on neuropsychological tests such as the Wisconsin Card Sorting Test and the Tower of London test.

A recent review of the literature provided additional support for the existence of pervasive cognitive deficits (Hammar et al., 2009):

Research during the past decade has mainly focused on cognitive functioning in the severe phase of depression, and today it is widely accepted that the disease is characterized by cognitive impairment in the acute state. There are reports of findings in different cognitive domains, such as executive functions, attention, memory and psychomotor speed.

Well (you say), what about Social Dilemmas? Aren't these different from the Stroop task? The Psych Review manifesto on the Bright Side of Being Blue states that "Complex social problems may be the primary evolutionarily relevant trigger of depression in human beings." But support for the view that depression improves the ability to solve such problems is meager, apparently consisting of two old papers (Hokanson et al., 1980; Pietromonaco & Rook, 1987). The Hokanson paper turns out to be not-so-great for the analytical rumination hypothesis: (1) The "depressed" group had scores on the Beck Depression Inventory of 10 or greater, which includes those with only very mild depression. (2) Ironically, Hokanson et al. view their own results as evidence of social skills deficits, not enhanced social problem solving:

If, indeed, depressed individuals display different social responses, depending on situational or social role variables, one might expect that real-world relations are characterized by contradictory behaviors, mixed messages, emotional ambivalence, and so forth. Such stimulus arrays may indeed evoke several competing response tendencies in others, a situation that a simple reinforcement-punishment view would be hard pressed to handle.

The conclusion of the Pietromonaco and Rook (1987) paper is even more problematic:

This work suggests that depressives' cognitive analysis of common life situations leads them to make decisions that promote their social isolation and, thereby, perpetuate their depression.

The analytical rumination hypothesis even has the potential to be harmful. Belief in the glorious "upside" of their ailment could prevent some severely depressed individuals from getting proper treatment, placing them at greater risk of suicide and other adverse events. Needless to say, such an outcome would be of no evolutionary advantage.

References

Andersson S, Lövdahl H, Malt UF. (2010). Neuropsychological function in unmedicated recurrent brief depression. J Affect Disord. Jan 18. [Epub ahead of print]

Andrews PW, Thomson JA Jr. (2009). The bright side of being blue: depression as an adaptation for analyzing complex problems. Psychol Rev. 116:620-54.



Baune, B., Miller, R., McAfoose, J., Johnson, M., Quirk, F., & Mitchell, D. (2010). The role of cognitive impairment in general functioning in major depression. Psychiatry Research DOI: 10.1016/j.psychres.2008.12.001

Forgas JP (2007). When sad is better than happy : Negative affect can improve the quality and effectiveness of persuasive messages and social influence strategies. J Exp Social Psychol. 43:513-528.

Åsa Hammar, Guro Årdal (2009). Cognitive functioning in major depression – a summary Frontiers in Human Neuroscience. DOI: 10.3389/neuro.09.026.2009

Hammar A, Sørensen L, Ardal G, Oedegaard KJ, Kroken R, Roness A, Lund A. (2009). Enduring cognitive dysfunction in unipolar major depression: A test-retest study using the Stroop paradigm. Scand J Psychol. 2009 Dec 23.

Hokanson JE, Sacco WP, Blumberg SR, Landrum GC. (1980). Interpersonal behavior of depressive individuals in a mixed-motive game. J Abnorm Psychol. 89:320-32.

Pietromonaco PR, Rook KS. (1987). Decision style in depression: The contribution of perceived risks versus benefits. J Personality Social Psychology 52:399-408.


Supplementary Material

Below is a box/blob and arrow diagram of the analytic rumination model (click on image for a larger view). A critique of its ludicrous biological underpinnings is beyond the scope of this post.

Figure 1 (Andrews & Thomson, 2009). A diagram of the proposed causal relationships between the variables and the constructs that are prominent in the analytical rumination hypothesis. The diagram uses the terminology of structural equation modeling [NOTE: but none of its quantitative rigor], with the circles representing latent constructs, the rectangles representing manifest variables, and the arrows denoting the hypothesized direction of causation. The plus (+) sign denotes a positive or facilitative causal relationship between variables, and the minus (-) sign denotes a negative or inhibitory causal relationship. 5-HT = 5-hydroxytryptamine or serotonin; L-VLPFC = left ventrolateral prefrontal cortex; R-VLPFC = right ventrolateral prefrontal cortex; WM = working memory.