A contingent negative variation study in patients with affective disorder

Yingzhi LU; Wenbin ZONG; Qingtao REN; Jinyu PU

ABSTRACT

BACKGROUND:

Contingent negative variation (CNV) is a kind of cerebral evoked potential, which is closely related with mental medicine and psychology.

OBJECTIVE:

To investigate the different manifestations between patients with affective disorder and normal adults in CNV detection.

DESIGN:

Case-control trial.

SETTING:

Department of Function, Psychiatric Hospital of Zibo, Shandong Province.

PARTICIPANTS:

Totally 29 inpatients and outpatients including 14 males and 15 females with affective disorder in the Fifth People's Hospital of Zibo between February 2005 and January 2006 were selected. The guardians were all informed and agreed the content; the diagnosed criteria of the patients were accorded wit h the criteria of DSM-Ⅳ. According to their mental status when hospitalized, the patients were divided into manic episode group and depressive episode group. There were 11 cases in the manic episode group, whose scores of Bech-Rataelson Mania Scale (BRMS)＞16; there were 18 cases in the depressive episode group, including unipolar depression (without history of mania episode) and bipolar depression (with history of mania episode) whose Hamilton Depression Scale (HAMD)scores ＞ 24. A total of 27 healthy hospital staff were selectedas control group including 14 males and 13 females aged 21-53 years and the mean age was (32.5±5.9) years. There was no significant difference in the age and sex among the three groups.

METHODS:

The CNV test was carried out in a soundproof room. Seating on a soft chair, the subject kept vigilant and focused on a fixed point in the front. The platinum electrode of 8 mm was attached to the subject's vertex Cz according to the International 10/20 System, referred to the right mastoid. The middle point of 2 eyebrows was grounded. The CNV waveforms were described by a L2-3 XY Functional Plotter. Standard CNV was composed of light signal and click signal. The flashlight and loudspeaker were located at the right back of the examinee. The subject was asked to press the button with his right finger to cut off the short sound as soon as his ears received the imperative click. It would take 2 500 ms for one CNV trial, and 20 trials as one experiment. Every subject was given the experiment for twice, and the standard amplitude was set by inputting a standard voltage of 20 μV to the same recording system.MAIN OUTCOME

MEASURES:

The CNV latency, amplitude B, area of negative expectancy wave before command signal, and area of negative change post-imperative negative variation (PINV) latency of the subjects in the two groups.

RESULTS:

All the 56 patients were involved in the result analysis.Compared with the control group, the mania group showed higher CNV amplitude [(22.8±4.8) μV; (16.0±5.7) μV; P ＜ 0.01], and the depression group presented smaller A-S2 area [(292.8±161.6)μV2; (412.8±159.9) μV2;P ＜ 0.01], and prolonged PINV latency [(261.9±79.3), (211.9±36.3) ms; P＜ 0.05]. The prolonged PINV latency was found in the unipolar depression group compared with the bipolar depression group [(344.5 ±66.9),(230.4±83.8) ms; P ＜ 0.01].

CONCLUSION:

CNV and PINV suggest that prolonged latency is the trait maker of the patients with unipolar depression, and CNV amplitude changes belong to the state makers of affective disorder.