Women are more likely to have unusual or unexplained tiredness and nausea or vomiting as symptoms. Women having heart attacks are more likely to have palpitations, back pain, labored breath, vomiting, and left arm pain than men, although the studies showing these differences had high variability. Women are less likely to report chest pain during a heart attack and more likely to report nausea, jaw pain, neck pain, cough, and fatigue, although these findings are inconsistent across studies. Women with heart attacks also had more indigestion, dizziness, loss of appetite, and loss of consciousness. Shortness of breath is a common, and sometimes the only symptom, occurring when damage to the heart limits the output of the left ventricle, with breathlessness arising either from low oxygen in the blood, or pulmonary edema. Other less common symptoms include weakness, light-headedness, palpitations, and abnormalities in heart rate or blood pressure. These symptoms are likely induced by a massive surge of catecholamines from the sympathetic nervous system, which occurs in response to pain and, where present, low blood pressure. Loss of consciousness due to inadequate blood flow to the brain and cardiogenic shock, and sudden death, frequently due to the development of ventricular fibrillation, can occur in myocardial infarctions. Cardiac arrest, and atypical symptoms such as palpitations, occur more frequently in women, the elderly, those with diabetes, in people who have just had surgery, and in critically ill patients. Absence
"Silent" myocardial infarctions can happen without any symptoms at all.
A proposed view is that dissociation has a physiological basis, in that it involves automatically triggered mechanisms such as increased blood pressure and alertness, that would, as Lynn contends, imply its existence as a cross-species disorder. A second area of controversy surrounds the question of whether or not dissociation as a defense versus pathological dissociation are qualitatively or quantitatively different. Experiences and symptoms of dissociation can range from the more mundane to those associated with posttraumatic stress disorder (PTSD) or acute stress disorder (ASD) to dissociative disorders. Mirroring this complexity, the DSM-5 workgroup considered grouping dissociative disorders with other trauma/stress disorders, but instead decided to put them in the following chapter to emphasize the close relationship. The DSM-5 also introduced a dissociative subtype of PTSD.A 2012 review article supports the hypothesis that current or recent trauma may affect an individuals assessment of the more distant past, changing the experience of the past and resulting in dissociative states. However, experimental research in cognitive science continues to challenge claims concerning the validity of the dissociation construct, which is still based on Janetian notions of structural dissociation. Even the claimed etiological link between trauma/abuse and dissociation has been questioned. Links observed between trauma/abuse and DD are largely only present from a Western cultural context. For non-Western cultures dissociation "may constitute a "normal" psychological capacity". An alternative model proposes a perspective on dissociation based on a recently established link between a labile sleep–wake cycle and memory errors, cognitive failures, problems in attentional control, and difficulties in distinguishing fantasy from reality.