634 Neurocognitive Disorders
Diagnostic Markers
Serum HIV testing is required for the diagnosis.  In addition, HIV charac terization of the cere-
brospinal fluid may be helpful if it reveals a disp roportionately high viral load in cerebrospinal
fluid versus in the plasma. Neuroimaging (i.e.,  magnetic resonance im aging [MRI]) may reveal
reduction in total brain volume, cortical thi nning, reduction in white matter volume, and
patchy areas of abnormal white matter (hyper intensities). MRI or lumbar puncture may be
helpful to exclude a specific medical condition such as cryptococcus infection or herpes en-
cephalitis that may contribute to CNS changes in the context of AIDS. Specialized techniques
such as diffusion tensor imaging may reveal  damage to specific white matter tracts. 
Functional Consequences of Major or Mild 
Neurocognitive Disorder  Due to HIV Infection
Functional consequences of ma jor or mild NCD due to HIV infection are variable across
individuals. Thus, impaired executive abiliti es and slowed information processing may
substantially interfere with the complex dise ase management decisions required for ad-
herence to the combined antire troviral therapy regimen. The likelihood of comorbid dis-
ease may further create functional challenges. 
Differential Diagnosis
In the presence of comorbidities, such as other infections (e.g., hepati tis C virus, syphilis),
drug abuse (e.g., methamphetamine abuse), or  prior head injury or neurodevelopmental
conditions, major or mild NCD due to HIV infe ction can be diagnosed provided there is ev-
idence that infection with HIV has worsened any NCDs due to such preexisting or comorbid
conditions. Among older adults, onset of neur ocognitive decline rela ted to cerebrovascular