The Hopkins HIV Report
A bimonthly newsletter for healthcare providers
Volume 8, Number 4, November 1996

Minor Cognitive Motor Disorder: Does It Really Exist?

By Justin C. McArthur, M.B., B.S., M.P.H.

Since 1991, investigators have used the term Minor Cognitive Motor Disorder (MCMD) to describe neurological and neuropsychological symptoms and signs which are not severe enough to meet criteria for frank dementia. It is estimated that 20-30% of individuals with advanced HIV infection (CD4 cell counts < 200 mm3) may show evidence of some impairment of cognitive or motor performance. In recent years the significance of these "minor" abnormalities has become better understood; however, it is still uncertain whether a "predementia syndrome" can be clearly characterized, and if it can, whether aggressive early treatment can forestall the development of frank dementia.

The incidence and prevalence of MCMD are poorly understood. This is primarily because diagnostic criteria are relatively new, and insufficient epidemiological research has been completed. The rate of MCMD is low in medically asymptomatic HIV infection (5%) but increases to about 25% during the symptomatic phases of the disease. In contrast, frank HIV dementia was detected in 0.8% of medically asymptomatic individuals, in 2.6% of symptomatic, and 7.0% of those with clinically-defined AIDS.

MCMD may be associated with increased mortality, and this increased risk of death applies not only to those who become frankly demented. Mayeux and colleagues, for example, reported earlier death in those who were neuropsychologically impaired but not demented. In addition to its possible prognostic significance, MCMD also has a clear impact on function. For example, in a cohort of individuals with advanced HIV infection, functional performance was significantly worse among those with MCMD than among HIV-infected individuals without neuropsychological impairment.

MCMD may not necessarily progress to frank dementia. In fact, some individuals with MCMD may improve when retested, possibly indicating some reversibility in the neurologic dysfunction. Why some people improve over time remains an open question. While the most obvious answer may be "practice effect" and other sources of error in neuropsychological measurement, another possibility is that the mildest form of brain disorder associated with HIV might actually have a fluctuating course, somewhat akin to what is found in demyelinating disorders. It is clear now that even during the lengthy asymptomatic phase of HIV infection, bursts of viral replication occur, and there is no true viral latency. These "viral bursts" might be accompanied by further brain seeding influencing neuro-psychological performance.

In summary, although information on the "real life" implications of HIV-associated MCMD remains fragmentary, the available data indicate that such impairments may be associated with reduced work efficiency, greater likelihood of development of frank dementia, and earlier mortality. The implication is that screening of individuals with advanced HIV infection, who are at risk for HIV dementia and MCMD, is probably warranted. Simple bedside tests such as the HIV Dementia Scale (included below), which was developed in the Moore Clinic for the early detection of dementia, are particularly useful. In general, a score of 10 is suggestive of HIV associated cognitive impairment or dementia and would warrant additional neurologic consultation.

HIV Dementia Scale

Max ScoreScore Memory-Registration Give four words to recall (dog, hat, green, peach) - 1 second to say each. Then ask the patient all 4 after you have said them.)
4( )Attention1 Anti-saccadic eye movements: 20 (twenty) commands. ____ errors of 20 trials.
less than or equal to 3 errors = 4; 4 errors = 3; 5 errors = 2; 6 errors = 1; > 6 errors = 0)
6( )Psychomotor Speed Ask patient to write the alphabet in upper case letters horizontally across the page (use back of this form) and record time: ____ seconds.
less than or equal to 21 sec = 6; 21.1 - 24 sec = 5; 24.1 - 27 sec = 4; 27.1 - 30 sec = 3; 30.1 - 33 sec = 2; 33.1 - 36 sec = 1; > 36 sec = 0)
4( )Memory - Recall Ask for 4 words from Registration above. Give 1 point for each correct. For words not recalled, prompt with a "semantic" clue, as follows: animal (dog); piece of clothing (hat), color (green), fruit (peach). Give 1/2 point for each correct after prompting.
2( )Construction Copy the cube below; record time: ____ seconds.
(< 25 sec = 2; 25 - 35 sec = 1; > 35 sec = 0)
Total Score: ____/16

1Attention: Hold both hands up at patient's shoulder width and eye height, and ask patient to look at your nose. Move the index finger of one hand, and instruct patient to look at the finger that moves, then look back to your nose. Practice until patient is familiar with task. Then, instruct patient to look at the finger which is NOT moving. Practice until patient understands task. Perform 20 trials. An error is recorded when the patient looks towards the finger that is moving.

Department of Neurology
Johns Hopkins University

This article is from The Johns Hopkins University AIDS Service,
The Hopkins HIV Report: A bimonthly newsletter for healthcare providers.