Blurred Memory Function and Depression

Warning Sign and Symptom May Yield Possible Treatment

Are your memories blurred?
Are your memories blurred?. Chad Baker/Stone/Getty Images

Scientists are looking at the connection between depression and what's called "overgeneral" memory. Several studies have found a significant difference in the way memory works between people who are depressed and those who aren't. The connection suggests that therapy dealing with the functioning of memory may be helpful in treating depression.

What Is Overgeneral Memory?

Suppose you are being asked to respond to cue words with a single memory.
One of the cue words is "frustration." If you are not depressed, your answer may be, "I was really frustrated trying to get hold of a customer service representative by phone the other day." But if you are depressed, you might say, "I can never find what I'm looking for in my kitchen."

The first answer is a specific example of a frustrating experience. The second isn't a single memory at all - it puts together a group of similar incidents that were frustrating. In truth, you undoubtedly often do find what you're looking for, but you've retrieved only the negative memories and lumped them together.

The phenomenon is also called "unspecific memory," and some researchers refer to it as "overgeneral autobiographical memory," or OGM.

Examples of Overgeneral Memory

  • Cue word: Rejection
    Specific memory: "Mrs. Jones rejected the tree-trimming proposal I gave her."
    Overgeneral memory: "My proposals always get rejected."
  • Cue word: Peaceful
    Specific memory: "I felt really peaceful out on the water last time I went fishing."
    Overgeneral memory: "Going fishing makes me feel peaceful."
  • Cue word: Stupid
    Specific memory: "I felt really stupid when I got to my meeting without my briefcase yesterday."
    Overgeneral memory: "I'm always so stupid at meetings."

    Is OGM Always Bad?

    Not at all. Everyone recalls things unspecifically at times. For example, if you ask me, "What's your one favorite memory about your mother?" I might answer, "I loved going with her to her singing lessons," or, "The time she came 400 miles to stay with me when I was really sick." One is general, the other specific. The answer about her singing lessons constitutes a group of wonderful memories - it's just not a correct answer to the question.

    The key is the frequency of unspecific memory retrieval versus specific. The more a person's memories are recalled in generalities, the more likely it is he or she will develop some type of depression. And a person with depression is highly likely to have this more general type of recall.

    Why Does Memory Become Unspecific?

    No one knows for sure, but there are some theories. One is that this type of memory functioning begins to develop early in people who are vulnerable, for whatever reason, to depression, bipolar depression, and at least some anxiety disorders.
    A group of researchers called it a "trait marker" for those illnesses.

    Another theory is that overgeneralized memory develops initially to help some people cope. It's based on the idea that "being less specific might help to prevent negative or painful emotions by recalling events in a less specific way." According to this theory, overgenerality "might have beneficial effects in the short run (less emotional impact of stressful events) but is detrimental in the long run."

    Memory Retrieval Change and Trauma

    A correlation has also been found between post-traumatic stress disorder and overgeneralized autobiographical memory. One study looked at children who were (1) abused, (2) neglected, and (3) not mistreated at all. They found the abused children scored higher for unspecific memory retrieval than the other two groups, which reinforces the theory that OGM could be a coping mechanism that blurs the memories of individual traumatic incidents.

    Also supporting that theory is additional research on subjects exposed to wartime trauma as children. This research suggests that "overgeneral memory retrieval strategy is at first protective, and a risk factor for depression only upon reaching adulthood."

    But what about people who didn't suffer specific trauma and still have depression or bipolar depression?

    The Connection to Depression

    The research is firm: people who have mood disorders tend to have much more overgeneralized memory function than those who don't. It's also well-established that overgeneral memory is a predictor of future depression.

    In addition, this type of memory process is often (though not always) found to continue in people with a history of depression even when they are not currently depressed. "This is significant," said one group of researchers, "because it means that the phenomenon can be observed without needing to be activated by low mood and might therefore act as a between-episode 'marker' of future vulnerability to depression."

    One recent analysis shows that "there is a small but reliable relationship between OGM and the course of depression." The authors of that analysis go on to say that in spite of these findings, they recommend testing methods of increasing memory specificity as one possible therapy for depression, in conjunction with other treatment (possibly cognitive behavioral therapy), and also recommend additional research into the relationship as a whole.

    The Take-Away Message

    Although more research is needed, it appears that the way your memory works may have an effect on your depression. If you have trouble recalling specific memories, or if you find you remember groups of events in general rather than specific events, these are indicators of overgeneral memory. In any case, it might be worth your while to bring the issue up with your doctor. Very limited data suggest that working to improve recall of specific events may help relieve depression symptoms. There is doubtless going to be much more research into the effectiveness of such therapy.

    Related Information:

    Sources:
    Lloyd GG, Lishman WA. Effect of depression on the speed of recall of pleasant and unpleasant experiences. Psychological Medicine. 1975 May;5(2):173-80.
    Hermans, D., et al. Autobiographical memory specificity and affect regulation: coping with a negative life event. Depression and Anxiety. 2008;25(9):787-92.
    Gee, A. Hazy Recall as a Signal Foretelling Depression. The New York Times. 9 May 2011.
    Lopez, N.H. Abused children and overgeneral memories: Could they lead to depression? Child-Psych.org. 15 Apr 2009.
    Brennan, T., et al. Trauma exposure in childhood impairs the ability to recall specific autobiographical memories in late adolescence. Journal of Traumatic Stress. 2010 Apr;23(2):240-7.
    Williams, J.M.G., et al. Autobiographical Memory Specificity and Emotional Disorder. Psychological Bulletin. 2007 January; 133(1): 122-148.
    Sumner, J.A., Griffith, J.W. and Minekaa, S. Overgeneral Autobiographical Memory as a Predictor of the Course of Depression: A Meta-Analysis. Behaviour Research and Therapy. 2010 July; 48(7): 614-625.

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