<p></p><div>Major Depressive Disorder (MDD) is a chronic, recurring, and
debilitating mental disorder that significantly impairs occupational and/or
social functioning.&nbsp;<span style="font-size: 1rem;">Most individuals suffering from MDD
have recurring depressive episodes (10.3%) rather than a single lifetime
episode (4.1%) (</span><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4428540/" style="background-color: rgb(255, 255, 255); font-size: 1rem;">Kessler et al.,
2012</a><span style="font-size: 1rem;">).&nbsp;&nbsp;</span><span style="font-size: 1rem;">MDD also has been found to have
comorbidity with other DSM disorders such as anxiety disorder, substance abuse
and impulse control disorder (</span><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4428540/" style="background-color: rgb(255, 255, 255); font-size: 1rem;">Kessler et al.,
2003</a><span style="font-size: 1rem;">). OF the many symptoms, the main symptoms of MDD are d<span style="font-size: 1rem;">ysphoria, a</span><span style="font-size: 1rem;">nhedonia, v</span><span style="font-size: 1rem;">egetative presentation, or, a</span></span><span style="font-size: 1rem;">gitation.</span></div><h3><span style="font-size: 14px;"><b>Symptoms of Bipolar Depressive Disorders</b></span></h3><p><span style="font-size: 1rem;"></span></p><div>•Feeling sad or hopeless for more
than two weeks</div><div><div>•Forgetfulness</div><div>•Inability to concentrate</div><div>•Trouble making decisions</div><div>•Sleeping more than usual but still exhausted</div><div>•Less energy than normal</div><div>•Weight gain or loss</div><div>•Eating more or less than usual</div><div>•Not showing interest in typically enjoyed activities</div><div>•Isolating yourself</div><div>•Feels like you are moving and thinking slower than usual</div><div>•Thoughts of suicide also known as ideation</div><div><br></div>Individuals suffering from Bipolar 1 show symptoms of mania, Bipolar 2 show symptoms of hypomania.&nbsp;<span style="font-size: 1rem;">The main difference is
hypomania is a milder form of mania.&nbsp;</span>Hypomania last at least four days;
mania symptoms last for at least seven days.<br><img src="@@PLUGINFILE@@/BPD.jpg" alt="Bipolar Disorders" width="1000" height="587" class="img-responsive atto_image_button_middle"></div>

<div></div><div><span style="font-size: 1rem;"><div><br></div><div><br></div><div>Relatively few investigations of regional
brain function in manic patients have been published, but hemispheric
asymmetries distinguishing manic from control subjects cross-sectionally
appear to be a <u>fairly consistent</u><u>
finding </u>(Flor-Henry
and Koles, 1984; Migliorelli et al., 1993;
O’Connell et al., 1995;
Rubin et al., 1995; Al-Mousawi et
al., 1996; Gyulaiet al.,
1997).</div><div><br></div><div><div>In contrast to the unstable vigilance
regulation in mania, a <u>hyperstable</u><u>
vigilance regulation </u>may
be observed during depressive episodes (Ulrich, 1994).&nbsp;<span style="font-size: 1rem;">This goes in parallel with a difficulty
falling asleep, an inner restlessness, and a hyperactivity of the
hypothalamic-pituitary-adrenal axis often found in depressed patients.</span></div><div><span style="font-size: 1rem;"><img src="@@PLUGINFILE@@/Vigilance%20MOdeling.png" alt="Vigilance MOdeling" width="673" height="500" class="img-responsive atto_image_button_left"><br></span></div><div><span style="font-size: 1rem;"><img src="@@PLUGINFILE@@/Vigilance%20in%20BPD.png" alt="Vigilance in BPD" width="648" height="480" class="img-responsive atto_image_button_middle"><br></span></div></div></span></div><div><span style="font-size: 1rem;">According to Siddiqui et al. (2008),&nbsp;<span style="font-size: 1rem;">MDD patients reliably show reduced
brain activity in frontal areas during waking, a phenomenon known as </span><u style="font-size: 1rem;">hypofrontality</u><u style="font-size: 1rem;">.</u><span style="font-size: 1rem;">&nbsp;</span><u style="font-size: 1rem;">Hypofrontality</u><u style="font-size: 1rem;"> </u><span style="font-size: 1rem;">is a significant dysfunction in the
activation of the prefrontal cortex , typically associated with deficits in
attention, action planning, working memory and sleep.</span></span></div><div><span style="font-size: 1rem;"><span style="font-size: 1rem;"><br></span></span></div><div><p>Emotional valence-related hemispheric
asymmetry appears to be a well-replicated phenomenon across several different
types of research pertinent to the question. Asymmetries have been found in
prefrontal cortex, temporal lobes,&nbsp;<span style="font-size: 1rem;">basal ganglia, thalamus and cingulate.
Differences in results for depressed populations with PET, SPECT and QEEG
are at least in part due to differences in subject selection, neuroanatomic
region of interest, determination, or data analysis methodology Gainotti,
1984; Coffey, 1987; Kahn et al., 1988; Goodwin and Jamison, 1990; Pollock and
Schneider, 1990b; George et al., 1993).</span></p><span style="font-size: 1rem;"><div><div>Otherwise, a variety of other depressed patient–control differences in asymmetry measures
have been reported in academic literature: </div>

<div>•Right &gt; left parietal alpha
(Davidson et al., 1985; Henriquez and Davidson, 1990; Allen
et al., 1993);
</div>

<div>•L &gt; R hemisphere delta in depressed
(Knott and LaPierre, 1987); </div>

<div>•Increased slow-wave activity on the
right (Kwon et al., 1996); </div>

<div>•Decreased anterior
interhemispheric coherence (Lieber and Prichep,
1988); </div>

<div>•Slow-wave interhemispheric
coherence (Lieber, 1988); </div>

<div>•Increased right hemisphere
variance (Rochford et al., 1981).</div>

<div>•Bilaterally increased frontal
alpha is frequently reported in literature (Schaffer et al., 1983; von
Knorring et al., 1983; Brenner et al., 1988; John et al., 1988; Lieber and Newbury,
1988; Pollock and Schneider, 1990a).</div><h3>The Frontal Asymmetry Debate</h3><p></p><div>Many studies find higher alpha activity
at the left hemisphere for MDD subjects when compared to healthy controls
(Schaffer et al., 1983; Davidson et al., 1985; Henriquez and Davidson, 1990;
Roemer et al., 1992; Allen et al., 1993).&nbsp;&nbsp;<span style="font-size: 1rem;">Alpha asymmetry is thought to be related to the
approach-withdraw model (Coan and Allen, 2004; Davidson, 1995) which posits that left
side frontal brain activity is related to approach behavior whereas the right
frontal side is related to withdraw behaviors.&nbsp;Alpha band at left side hemisphere seen in depression, since alpha is related to lack of activity in the brain, increased alpha at the left side of the brain indicates lower activity and therefore may indicate lack of approach behavior.&nbsp;</span><span style="font-size: 1rem;">Lee et al. (2018 ) and Hosseinifard et al., (2013) report higher alpha at the left side of
the brain for depressed compared to euthymic (emotional stable) subjects.</span></div><p></p></div></span></div><p></p>