accumulation is associated with an increased risk of neurocognitive impairment
for HIV-positive patients, according to a study published in the February
edition of Neurology. Overall 40% of
patients in the study were diagnosed with impairment and increased waist
circumference was a significant risk factor. Diabetes was also a factor, but
only for patients aged 55 and over.
a measure of central obesity and a risk factor for insulin resistance and
atherosclerosis contributed to neurocognitive impairment,” comment the authors.
They note that their findings accord with research conducted in the general
population which “identified…effects on cognition by central obesity as
measured by waist circumference or hip-to-waist ratio.”
can significantly prolong the life expectancy of patients with HIV. However,
this treatment can cause a number of side-effects, including metabolic
abnormalities. Disturbances in the way the body stores and processes fat are
now well-recognised complications of some antiretroviral regimens. There is
concern that long-term use of anti-HIV drugs could increase the risk of
diabetes and cardiovascular disease.
neurocognitive impairment among HIV-positive patients are also high. The exact
prevalence is controversial. So too are the causes, but these could include
metabolic disturbances and diabetes, recognised risk-factors for neurocognitive
impairment in the general population.
Investigators from the
US CHARTER (CNS HIV Anti-Retroviral Therapy Research) group wanted to clarify
the relationship between metabolic disturbances and neurocognitive impairment
in patients with HIV.
designed a cross-sectional study involving 130 patients who received care
between 2006 and 2007. These patients completed a standard test to assess their
cognitive function. The results were adjusted to take account of age,
education, gender and race. Fasting blood samples were obtained to determine
levels of total cholesterol, HDL-cholesteral, LDL-cholesterol, triglycerides
and the prevalence of insulin resistance. Waist circumference was measured and
body mass index (BMI) assessed.
HIV-related factors including duration of infection, use of HIV therapy, CD4
cell count and viral load was also obtained.
The patients had a
mean age of 46 years, 57% were white and 87% were men.
Overall, 40% of
patients had some form of cognitive impairment.
The first analysis
revealed a number of risk factors for this condition. These included older age
(48 vs. 44 years, p = 0.02), longer duration of infection with HIV (15 vs. 12
years, p = 0.03) and increased waist circumference (99 vs. 88 cm, p = 0.0005).
Patients with impairment were also significantly more likely to have been
diagnosed with diabetes (15% vs. 3%, p = 0.007).
A total of ten
patients were diabetic and eight (80%) had neurocognitive impairment. This
compared to a prevalence rate of 37% among non-diabetic patients.
explored the apparent association between diabetes and impairment in a larger
population totalling over 1300 individuals. They found some evidence of a
relationship between diabetes and neurocognitive impairment, but only among
patients aged 55 and above.
“Thus, if diabetes
contributes to neurocognitive impairment, it may do so only in older patients,”
write the authors.
was then undertaken to see which metabolic and HIV-related factors increased
the risk of impairment.
The first analysis
included the 90 patients with a restricted dataset. BMI rather than waist
circumference was used as a marker of body composition. The results showed that
age (p = 0.027) and BMI (p = 0.039) were both predictors of impairment.
A second model
included the 55 patients for whom information on waist circumference was
available. BMI (p = 0.038) and waist circumference (p = 0.001) both predicted
impairment, as did an AIDS diagnosis (p = 0.027).
believe that BMI was only significant because “it is a marker of waist
They add, “central,
rather than generalised obesity conveys increased risk…for neurocognitive
impairment.” The authors believe this finding has implications for the use of
HIV therapy. “These findings suggest that the selection of combination
antiretroviral therapy that induces less central obesity might reduce the risk
of HIV-associated brain damage and cognitive impairment.”
A possible mechanism
whereby central fat accumulation is contributing to neurocognitive impairment
was suggested by the investigators. “Systemic inflammation…or adipose derived
hormones may mediate generalised or focal cerebral degeneration that leads to