ERPs differ from neurometric tests in assessing HIVassociated cognitive deficit

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ERPs differ from neurometric tests in assessing
HIV-associated cognitive deficit

• Tartar JL, Sheehan CM, Nash AJ, Starratt C, Puga
  A, and Widmayer S. Neuroreport. 2004 Jul 19
  15(10)1675-8

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Introduction HIV Cognitive Impairment

• Depression
• Apathy
• Failure to pursue treatment
• General Cognitive Decline (over time)
• Memory problems
• Alzheimers
• Parkinsons
• Dementia

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Measuring cognitive impairment

• Early detection of neuropsychological impairment
  earlier treatment that could minimize
  progression
• Neurometric testing aka Pen Paper tests
• Measure verbal learning, memory, and overall
  intelligence
• limited specificity in detecting HIV-associated
  cognitive decline subclinical changes in
  patients
• Previous studies discrepencies in measuring
  cognitive decline in symptomatic vs. asymptomatic
  patients

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Symptomatic vs. Asymptomatic HIV patients

• CDC Definitions

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Objective Discriminate stages of infection via
physiological measures

• Novel approach physiological neurometric
  assessments
• ERP of EEG (event-related potentials of
  electroencephalogram)
• Can detect cognitive deficits that are
  involuntary and subclinical
• Cognitive deficit long latency smaller
  amplitude waveforms in specific ERP components

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Subjects

• HIV symptomatic women (n11)
• HIV asymptomatic women (n12)
• HIV- control group (n11)
• Groups determined by CDC definitions
• 18 to 35 years similar socio-economic status,
  education level, drug and alcohol use
• Childrens Diagnostic and Treatment Center (CDTC)
  Ft. Lauderdale, FL
• Women vs. Men

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Electrophysiological Procedures

• Electrodes attached at Fz, Cz,C3, C4, Pz
• Auditory stimulus of 1000 Hz (low) 2000 Hz
  (high)-20 trials
• Classic oddball condition

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Neurometric Procedures

• Trail Making Test visuomotor tracking, cognitive
  executive functions (attention)
• WAIS Digit span subtest of Wechsler Adult
  Intelligence Scale. Assesses individual
  intelligence, short-term, working memory
• HVLT Hopkins Verbal Learning Test

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ERP Components Analyzed

• p3 positive, peak at 350 ms
• Latency amplitude differentiated groups

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P3 amplitude latency differentiated HIV groups
from controls

• Amplitude greater mean amplitudes for controls
  (14.37) than average of two clinical groups
  (8.84)
• Latency shorter mean latencies for controls
  (381.82 ms) than the clinical groups (426.51 ms)

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Neurometric Tests Differentiated Within Clinical
Groups

• Trail Making Tests
• Asymptomatic patients significantly faster
  completion times overall (68.91) than symptomatic
  patients (103.20)
• WAIS-Digit Span
• Asymptomatic patients scored higher overall
  (15.90) than symptomatic patients (11.90)
• Hopkins Verbal Learning
• Asymptomatic patients demonstrated significantly
  higher overall scores (25.82) than symptomatic
  patients (20.64)

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Results of Neurometric Tests
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Discussion

• P3 component of ERP distinguishes HIV(A)
  HIV(S) from healthy controls
• Neurometric tests distinguishes between HIV (A)
  HIV(S) patients
• Complementary uses
• Specific deficits not studied previously

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Discussion

• P3 of auditory ERP early indicator of cognitive
  decline in HIV women
• Lower p3 amplitude suggests reduced attentional
  resources
• Higher p3 latency suggests compromised speed of
  processing
• Otherwise asymptomatic patients show cognitive
  decline neurometric tests lack sensitivity to
  detect early cognitive impairment

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Discussion

• HIV invades CNS early
• Early detection of HIV-associated cognitive
  impairments early diagnosis treatment
• Neurometric tests asymptomatic patients scored
  higher than symptomatic patients on ALL measures
• Sensitive to different aspects of HIV-associated
  cognitive decline

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Conclusion

• P3 component of auditory ERP
• sensitive to different aspects of HIV-associated
  cognitive decline
• discriminate HIV (SA) from controls
• Neurometrics
• sensitive to degree of decline within HIV
  classifications
• Both measures useful complementary in diagnosis
  treatment of HIV-associated CNS impairment