There are emotional changes in mercury poisoning. Depression slowly sets in. Victims feel fatigued and listless. They lack motivation - even for crucial tasks. They lose interest in their surroundings and in their own life. They do not enjoy life, or experience happiness or joy. They experience constant fear e. g. of losing their job. They may be very tense. They feel hopeless. They have a sense of impending doom. Every small problem is discouraging. Minor difficulties seem overwhelming and insurmountable.
The altered emotional state of a mercury intoxicated person leads to impaired interpersonal relationships. They become increasingly irritable and sensitive, reacting strongly to relatively innocent remarks. They may not be able to take orders, instructions, or suggestions without losing their temper. They resent criticism and may interpret innocent remarks critically. They may have an exaggerated response to stimulation and become fearful or anxious and nervous. They may project their fears and anxieties onto others, making inappropriate criticisms or attacks. They become shy and avoid dealing with strangers. While timid, they may unexpectedly lose self control with strangers. They may wish to visit with friends and family extensively, often wishing to engage in long, repetitive conversations, then withdraw for prolonged periods of time. They withdraw more and more from social contacts.
Intelligence gradually deteriorates. Previously bright persons become dull and slow in thinking. They suffer from a progressive decline specifically affecting short term memory as well as the faculties for logical reasoning. Thus their ability to do things like balance the checkbook, do math, or play chess suffers. They lose the ability to concentrate. Memory problems may be more from distractability and inability to concentrate and pay enough attention to get things INTO their memory than an actual failure to remember things (thus they may complain of memory problems but do well on memory tests). They cease being motivated towards their work or other tasks. Thoughts become heavy, repetitive and pedantic. Creative thinking becomes progressively more difficult, eventually becoming impossible. They become unable to select the right words to convey their meaning, and make stylistic and grammatical errors. Their ability to express themselves declines progressively.
There is a distinctive cognitive symptom of being unable to think clearly without great effort. The best description for people who have not experienced it is of a hangover without pain. People who have experienced it will recognize the term "brain fog" as entirely descriptive.
As the victim's level of intoxication waxes and wanes they go through periods of life when they do or do not dream. Dreaming may be in black and white.