Mental disorders that can have symptoms similar to those seen in bipolar disorder include schizophrenia, major depressive disorder, attention deficit hyperactivity disorder (ADHD), and certain personality disorders, such as borderline personality disorder. A key difference between bipolar disorder and borderline personality disorder is the nature of the mood swings; in contrast to the sustained changes to mood over days to weeks or longer, those of the latter condition (more accurately called emotional dysregulation) are sudden and often short-lived, and secondary to social stressors.Although there are no biological tests that are diagnostic of bipolar disorder, blood tests and/or imaging are carried out to investigate whether medical illnesses with clinical presentations similar to that of bipolar disorder are present before making a definitive diagnosis. Neurologic diseases such as multiple sclerosis, complex partial seizures, strokes, brain tumors, Wilsons disease, traumatic brain injury, Huntingtons disease, and complex migraines can mimic features of bipolar disorder. An EEG may be used to exclude neurological disorders such as epilepsy, and a CT scan or MRI of the head may be used to exclude brain lesions. Additionally, disorders of the endocrine system such as hypothyroidism, hyperthyroidism, and Cushings disease are in the differential as is the connective tissue disease systemic lupus erythematosus. Infectious causes of mania that may appear similar to bipolar mania include herpes encephalitis, HIV, influenza, or neurosyphilis. Certain vitamin deficiencies such as pellagra (niacin deficiency), Vitamin B12 deficiency, folate deficiency, and Wernicke Korsakoff syndrome (thiamine deficiency) can also lead to mania.
Toxic oil syndrome 
(TOS) or simply toxic syndrome (Spanish: síndrome del aceite tóxico or síndrome tóxico) is a musculoskeletal disease. A 1981 outbreak in Spain which affected about 20,000 people, with over 300 dying within a few months and a few thousand remaining disabled, is thought to have been caused by contaminated colza (rapeseed) oil. It was unique because of its size, the novelty of the clinical condition, and the complexity of its aetiology. Its first appearance was as a lung disease, with unusual features, though the symptoms initially resembled a lung infection. The disease appeared to be restricted to certain geographical localities, and several members of a family could be affected, even while their neighbours had no symptoms. Following the acute phase, a range of other chronic symptoms was apparent. Alternative mechanisms
The conclusion of the Joint WHO/CISAT Scientific Committee for the Toxic Oil Syndrome from 2002, that oil was the cause for TOS, is based only on epidemiological evidence, since up to now, experimental studies performed in a variety of laboratory animals have failed to reproduce the symptoms of human TOS. None of the in vivo or in vitro studies performed with toxic-oil-specific components, such as fatty acid anilides, and esters of 3-(N-phenylamino)-1,2-propanediol (abbreviated as PAP), have provided evidence that these markers are causally involved in the pathogenesis of TOS.Specifically, three possible causative agents of TOS are PAP (3-(N-phenylamino)-1,2-propanediol), the 1,2-dioleoyl ester of PAP (abbreviated OOPAP), and the 3-oleoyl ester of PAP (abbreviated OPAP).