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Hyperventilation and photic stimulation were used as Psychological evaluation
provocation tests. Standardized psychiatric interview was done by
applying the Diagnostic and Statistical Manual of
Cognitive assessment Mental Health Disorders, 4 edition (DSM‑IV) criteria
th
Cognitive functions were assessed independently for each for the diagnosis of depression. [44] A differentiation
participant by two experienced psychologists and under between clinical depression and depressive
supervision of a psychiatrist, using a set of standardized symptoms was made throughout clinical interview
Arabic translated neuropsychological tests that are of the patient. The Arabic version [45] of the Beck
sensitive for mild cognitive impairment and covering Depression Inventory, 2 edition (BDI‑II) [46] was used
nd
different cognitive domains. They included: Mini‑Mental to assess the severity of depressive symptoms. BDI‑II
State Examination (MMSE), [38,39] Stanford‑Binet items are in alignment with DSM‑IV criteria. BDI‑II
th
Intelligence Scale 4 edition (SBIS) [40,41] and Wechsler consists of 21 items each corresponds to a symptom
Memory Scale‑Revised (WMS‑R). [42] From SBIS, we of depression summed to give a single score for the
selected vocabulary and comprehension for assessment of BDI‑II. According to that scale, the patient may have,
verbal reasoning, pattern analysis for assessment of visual not having or has minimal depressive symptoms
reasoning, quantitation for quantitative reasoning, and if scoring 0‑13, mild symptoms if scoring 14‑19,
bead memory and memory for sentences for short‑term moderate symptoms if scoring 20‑28 and severe
memory. From WMS‑R, we tested digit forward digit symptoms if scoring 29‑63.
backward, mental control, associate learning, logical
memory, and visual reproduction. Statistical analysis
Calculations were done with the statistical package
Event related potentials testing SPSS, version 12.0 (SPSS Inc. Chicago, IL, USA). Data
Before examining ERPs, all participants underwent were presented as mean ± standard deviation. Student’s
basic audiological testing (Amplaid Model 720, Milan, t‑test was used for comparison of means. Correlations
Italy). Testing for ERPs was done on a separate day after between score of cognitive testing and demographic
completion of neuropsychological testing (Neuropack and clinical characteristics and depression scores
S1 EMG/EP measuring system, MEB‑9400 (Nihon were assessed using Pearson’s test. Linear regressions
Kohden, Japan). ERPs are series of scalp waves that are analyses were done using the total score of cognition
extracted from the EEG by time domain analysis and testing as the dependent variable and age, duration of
averaging of EEG activity following multiple stimulus illness and depression scores as independent variables.
repetitions. They were elicited with an auditory For all tests, P < 0.05 was considered as significant.
discrimination task paradigm by presenting a series
of biaural 1000 Hz (standard) versus 2000 Hz (target) RESULTS
tones at 70 dB with a 10 ms rise/fall and 40 ms plateau
time. P300, the late component of ERPs was obtained. This study included 20 patients with MG. They had a
Latencies and amplitudes (peak to peak) of P300 mean age of 28.45 ± 8.89 years and duration of illness of
component of ERPs were measured. The P300 wave 3.52 ± 1.15 years. Patients reported normal EEG records.
is a positive deflection in the human ERPs. It is most All patients had depressive symptoms of mild (n = 15,
commonly elicited in an “oddball” paradigm when a 75%) and moderate (n = 5, 25%) severities. Each
subject detects an occasional “target” stimulus in a patient had a different combination of abnormalities
regular train of standard stimuli. The P300 wave only in various cognitive testing subsets particularly
occurs if the subject is actively engaged in the task WMS‑R (n = 16, 80%). Patients had significantly
of detecting the targets. Its amplitude varies with the lower scores of MMSE, different subsets of SBIS,
improbability of the targets. Its latency varies with WMS‑R and total scores of cognitive testing (MMSE,
the difficulty of discriminating the target stimulus SBIS and WMS‑R) (P = 0.0001) and higher scores of
from the standard stimuli. Typical peak latency is BDI‑II (P = 0.0001) [Table 2]. The majority of patients
elicited when a young adult subject makes a simple had abnormalities in latency and/or amplitude of
discrimination in 300 ms. In patients with decreased P300 component of ERPs (n = 14, 70%). Patients
cognitive ability, the P300 is smaller and later than in had significantly prolonged latencies (P = 0.01) and
age‑matched normal subjects. The P300 have multiple reduced amplitudes (P = 0.001) of P300 component of
intra‑cerebral generators, with the hippocampus and ERPs [Table 3]. Significant correlations were identified
various association areas of the neocortex contribute to between total scores of cognitive testing and P300
the development of this potential. The P300 component latency, P300 amplitude, age, duration of illness and
of ERPs represents the transfer of information to depression scores [Table 4] Using linear regression
consciousness, a process that involves many different analysis and after controlling for age and depression
regions of the brain. [43] scores, significant correlation was identified between

Neuroimmunol Neuroinflammation | Volume 1 | Issue 3 | December 2014 143