Alberta: Factors Predictive of HIV-Related Neurocognitive Impairment

December 11, 2012

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Shortly after HIV enters the body, it infects cells of the immune system. These infected cells are transported by the lymphatic system and distributed to lymph nodes and tissues, where the virus can infect more cells. Within a week of initial infection, HIV has been spread in infected cells via the blood throughout the body, including the brain. HIV does not infect brain cells but it does infect cells of the immune system that travel to or are resident within the central nervous system (CNS) -- the brain and spinal cord.

HIV-infected cells release chemicals that impair the functioning of brain cells. Infected cells also trigger inflammation within the CNS. Together, these cause dysfunction within the brain. In cases of untreated HIV infection this can lead to problems affecting neurocognitive abilities such as thinking clearly, memory and concentration. In extreme cases, changes in personality could occur and loss of control of key muscles and reflexes could become issues.

Fortunately, the widespread availability of potent combination anti-HIV therapy (commonly called ART or HAART) in Canada and other high-income countries has tremendously improved the health and well-being of HIV-positive people who are engaged in their care and treatment. Researchers increasingly expect that HIV-positive people with minimal pre-existing health conditions and who can adhere to therapy will have near-normal life spans.

Today, cases of moderate or severe neurocognitive impairment are no longer common. Neurocognitive dysfunction, if present, is generally mild and symptom free, thanks to ART. Such dysfunction is usually detectable only with complex testing. Mild neurocognitive dysfunction usually does not affect a person's ability to carry out everyday activities.



Researchers in Alberta have been monitoring about 1,300 HIV-positive participants in a long-term study where they sought factors linked to the development of HIV-related neurocognitive problems.

Over a period of 10 years, they found that 7% of participants developed such symptoms and had the following profile compared to participants who did not have symptoms:

  • they were older
  • they were living with HIV longer
  • their lowest-ever CD4+ count (called the nadir) was about 100 cells
  • they had a high pre-treatment HIV viral load (greater than one million copies/ml)

Note Well

It is important to note that not everyone with these factors developed symptoms of HIV-related neurocognitive dysfunction. However, having factors from the list above was associated with an increased relative risk for developing such problems.

The Alberta team says that doctors and nurses in clinics can use these findings when making decisions about which HIV-positive patients should be prioritized for screening for neurocognitive dysfunction.

Study Details

Researchers in Calgary and Edmonton reviewed health-related data collected from January 1998 to September 2008 from 1,320 HIV-positive participants. Study participants visited the Southern Alberta Clinic every three or four months to undergo laboratory testing and be interviewed. At each visit the participant and/or his or her caregiver or family member was questioned about new symptoms of neurocognitive problems, including the following:

  • forgetfulness
  • poor concentration
  • confusion
  • problems with walking, balance and control of muscles

If such symptoms were present, participants underwent brief neurocognitive assessment. If this initial assessment confirmed the presence of neurocognitive dysfunction, participants were referred to a neurologist experienced with HIV-positive people for a comprehensive screening.

Comprehensive Neurological Screening

This involved the following:

  • a complete medical history
  • a physical examination

If deemed necessary, further assessments were done, such as the following:

  • CT or MRI scans of the brain
  • a spinal tap to analyse the fluid that bathes the brain and spinal cord (the cerebrospinal fluid)

Furthermore, blood tests were done to exclude problems that could affect the functioning of the brain, including the following:

  • dysfunction of the thyroid gland
  • syphilis
  • higher-than-normal levels of medication in the blood

Additionally, the neurologist screened participants for the following issues that can cause neurocognitive impairment:

  • anxiety
  • depression
  • substance use
  • inherited neurological problems

Participants also underwent extensive neurocognitive testing.

Finally, a team consisting of a nurse, physician and social worker reviewed each participant's results, and the diagnosis of neurocognitive disorder was made by consensus.

The average profile of participants upon entering the study was as follows:

  • 1,068 men and 252 women
  • age: 44 years
  • length of time HIV-positive: 10 years
  • lowest-ever CD4+ count: 174 cells
  • HIV viral load: 161,000 copies/ml
  • HCV co-infection: 277 participants


Overall, 90 participants developed symptoms of neurocognitive dysfunction, graded as follows:

  • minor neurocognitive dysfunction: 19 participants
  • HIV-associated dementia: 71 participants
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This article was provided by Canadian AIDS Treatment Information Exchange. It is a part of the publication CATIE News. Visit CATIE's Web site to find out more about their activities, publications and services.

Reader Comments:

Comment by: Ron (Delafield, WI) Wed., Jan. 23, 2013 at 10:21 am UTC
I have the history that may include me in the group which is at higher risk for neurocognitive dysfunction. I also have a history of the factors that were also screened, i.e., anxiety, depression, substance use and inherited neurological problems. I have experienced some dysfunction already. Is there anything that can be done to slow, stop or reverse the damage?
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Comment by: Dr Billy Levin (South Africa) Tue., Jan. 22, 2013 at 11:53 pm UTC
ADHD is prevalent in approx. 10% of children. In HIV positive children 28% have ADHD. There is obviously the genetically inherited factor but the inflammatory effect of the virus on brain is an aggravating factor. Stimulants help but so does antibiotics of the Terramycin family mainly due to their anti-inflammatory action on brain, not the antibiotic action. Best results are when both are used. Terramcin has not only an antibiotic action but also and anti-inflammatory action both on skin in Acne and on brain as both are of Ectodermal origin in the embryo.
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