CATIE News - Studying memory provides clues for helping the brain
2011 Feb 17 - Some studies have suggested that older HIV-positive adults can have mild to
moderate deficits in what brain researchers call "working memory." According to neuropsychologist and associate professor of psychiatry
Steven Woods, PsyD, who teaches at the University of California at San Diego, a centre for excellence in neuroAIDS, working memory
refers to "the ability to hold, store and manipulate information in the brain." Deficits in working memory may play a major
role in some of the neurocognitive dysfunction seen in some HIV-positive adults.
While conducting a cross-sectional study with HIV-positive people, Dr. Woods and colleagues unexpectedly
found that some older HIV-positive adults had better assessments of working memory than younger HIV-positive adults. Specifically, it
appeared that some older participants had developed strategies, either deliberately or inadvertently, to help them remember the
locations of a series of visual designs. By comparison, older HIV-positive individuals who did not use strategies were far
more likely than younger HIV-positive persons to make working memory errors.
Remembering visual designs might seem trivial to non-scientists, but for neuropsychologists and other
scientists who study the brain, these tests provide important insight into memory.
Dr. Woods' team was intrigued by how effective spontaneous memory strategy use was in the older adults
and suspected that some older HIV-positive people somehow gained insight into their memory problems and found ways to compensate.
This suggests that it is possible to help HIV-positive people who have a mild-to-moderate degree of neurocognitive impairment
to overcome these difficulties.
Ideally it would have been best to have conducted a randomized controlled clinical trial that recruited
both HIV-positive and HIV-negative people for purposes of comparison. However, the findings by Dr. Woods' colleagues are exciting because
they document that the brains of older HIV-positive people may be able to develop effective strategies to compensate for some aspects
of HIV-related neurocognitive impairment.
What's next?
Rehabilitation programs for the brains of HIV-negative people who have suffered traumatic brain injury from accidents or strokes have been
developed. Some of these programs have been found to be successful in randomized clinical trials.
However, most otherwise-healthy HIV-positive people who take potent anti-HIV therapy (commonly called ART or HAART) do not have such a
serious degree of cognitive impairment as someone who has injured their head in a car accident or had a stroke.
So existing brain rehabilitation programs need to be adapted and tested to meet the needs of HIV-positive people.
There are also so-called brain training exercises that have been developed to help older HIV-negative adults improve and restore their ability to use
language and numbers. In an interview with CATIE News , Dr. Woods notes that brain training programs have not yet been formally tested with large numbers of HIV-positive people with
mild cognitive impairment. He makes the following points:
"It is not clear if such exercises can correct or compensate for the specific effects of HIV infection on the brain. Data are lacking for us to know
if early use of these programs in people without HIV-related cognitive impairment will delay the onset of these problems."
Until such data do become available, Dr. Woods says that brain training exercises, crossword puzzles, jigsaw puzzles and numeracy games such as Sudoku
represent "a low-risk investment, as for most HIV-positive people these exercises will not be harmful."
As more HIV-positive people are aging, they and their doctors are concerned about the possibility of accelerated decline of the brain. Neuroscientists
are studying memory and higher intellectual functioning to try to find ways to help HIV-positive people better cope with the effects of aging. Expect to hear results from these
studies in the next several years.
Resources
For additional information about improving brain health in the setting of HIV, see "A Mind of Her Own" by activist Maggie Atkinson in the winter 2010 issue
of CATIE's Positive Side magazine at:
www.positiveside.ca/e/V11I2/Mind_e.htm
-Sean R. Hosein
REFERENCES:
- Gongvatana A, Woods SP, Taylor MJ, et al. Semantic clustering inefficiency in HIV-associated dementia. Journal of Neuropsychiatry and Clinical
Neurosciences . 2007 Winter;19(1):36-42.
- Wegesin DJ, Jacobs DM, Zubin NR, et al. Source memory and encoding strategy in normal aging. Journal of Clinical and Experimental Neuropsychology . 2000 Aug;22(4):455-64.
- Baddeley A. Working memory: looking back and looking forward. Nature Reviews Neuroscience. 2003 Oct;4(10):829-39.
- Redondo RL, Morris RG. Making memories last: the synaptic tagging and capture hypothesis. Nature Reviews Neuroscience . 2011 Jan;12(1):17-30.
- Wang SH, Redondo RL, Morris RG. Relevance of synaptic tagging and capture to the persistence of long-term potentiation and everyday spatial memory. Proceedings of the National Academy of Sciences USA . 2010 Nov 9;107(45):19537-42.
- Miller GA. The magical number seven, plus or minus two: some limits on our capacity for processing information. Pschological Review . 1994 Apr;101(2):343-52.
- Woods SP, Weber E, Cameron MV, et al. Spontaneous strategy use protects against visual working memory deficits in older adults infected with HIV. Archives of Clinical Neuropsychology. 2010 Dec;25(8):724-33.
- Heaton RK, Clifford DB, Franklin DR Jr., et al. HIV-associated neurocognitive disorders persist in the era of potent antiretroviral therapy: CHARTER Study. Neurology . 2010 Dec 7;75(23):2087-96.
- Malaspina L, Woods SP, Moore DJ, et al. Successful cognitive aging in persons living with HIV infection. Journal of Neurovirology . 2011; in press .
From Canadian AIDS Treatment Information Exchange (CATIE). For more information visit CATIE's Information Network at http://www.catie.ca
Source: CATIE: CANADIAN AIDS TREATMENT INFORMATION EXCHANGE
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