Magnetic resonance imaging characteristics of visuospatial location defect in patients with mild cognitive impairment

Jing BAI; Xuchu WENG; Sheng XIE; Yinhua WANG

ABSTRACT

BACKGROUND:

Patients with Alzheimer disease (AD) usually have visuospatial dysfunction at an early stage and most patients with AD were evolved from mild cognitive impairment (MCI).

OBJECTIVE:

To detect whether a patient with MCI has a visuospatial dysfunction similar to AD. To compare the cerebral activation with ferromagnetic resonance between the healthy people and the patients with mild cognitive disorder.

DESIGN:

A case controlled observation

SETTING:

The Department of Neurology of the First Hospital of Peking University.

PARTICIPANTS:

Nine inpatients with mild cognitive disorder hospitalized at the Department of Neurology of the First Hospital of Peking University from April 2000 to March 2003 were involved and other 9 healthy people matching in age, gender and the educational level were also involved.

METHODS:

The subjects had the task of discriminating the different finger positions on the clockface. They could see the mission clearly showed on the cloth through refractor, and they were supposed to give the corresponding reaction to different cognitive tasks with left and right hands pressing the keys according to visual sign generated by the computer.Block design was adopted in the cognitive task. Stimulus block and baseline block appeared in turn. Baseline block displayed "+" mapped in the center of the image and was kept for 21s. Stimulus block displayed 10 pictures successively. The finger position of the two clockfaces among three clockfaces was the same in one picture. The absolute value of the rotated angles of the different clockfaces in each image on the same stimulus block was the same. The angles formed by six stimulus block fingers arranged randomly were 300, 450, 1800. The two clockfaces had the same finger positions, and the subjects were requested to discriminate the finger position of these two clockfaces. It was carried out on a 1.5 T GEMRTWIN magnetic resonance scanning apparatus. Then t test was performed to work out the right reaction time and proper rate with Excel software between the patients with mild Alzheimer's disease and the healthy persons. Pretreatment and statistical analyses were performed with analysis of functional neuroimages software used internationally.MAIN OUTCOME

MEASURES:

Comparison of the reaction time and proper rate between the two groups.parison of the reaction time between the two groups The reaction time for distinguishing the change of 300, 450, 1800 was longer than that in the control group, and there was significant difference in distinguishing the change of 300, 450, 1800 for the patients [(1 776.7±570.2), (1 646.3±432.7)ms;of the proper rate between the two groups The proper rate for distinguishing the change of 300, 450, 1800 was significantly lower than that in the control group (62.8±21.4)%, (82.8±15.8)% ;(76.7±17.0)%, (95.0±8.7)%; (69.4vation the activation density at the bilateral parietal lobe, bilateral temporooccipital borderline and bilateral lateral striate cortex in patients was weaker than that in the control group (P ＜ 0.05).

CONCLUSION:

Neural network activation related with visual space in patients with MCI was weaker than that in the healthy people indicating that visuospatial impairment exists in the patients with mild cognitive impairment.