Melasma Causes. Melasma is usually caused by the sun, hormones in birth control pills, hormone replacement therapy, medications and pregnancy. When Melasma is caused by pregnancy it is called chloasma. In some women, when the skin is exposed to sunlight, brown blotches of excess pigment form due to the interaction with hormones or chemicals. Melasma is believed to be hereditary and woman with darker skin tones tend to be more at risk for this disorder.
Some research suggests that the hippocampus may participate only in consolidation processes lasting a few years. The entorhinal cortex, on the other hand, gives evidence of temporally graded changes extending up to 20 years, suggesting that it is this region that participates in memory consolidation over decades. The entorhinal cortex is damaged in the early stages of Alzheimerâs disease.
If the amnesia is thought to be of psychological origin, it is termed psychogenic. Memory loss may result from bilateral damage to the limbic system of the brain responsible for memory storage, processing, and recall.(Illustration by Electronic Illustrators Group). Anterograde. 2  This form of amnesia follows brain trauma and is characterized by the inability to remember new information. 3  Recent experiences and short-term memory disappear, but victims can recall events prior to the trauma with clarity. 4  Retrograde.