Cognitive changes mean disturbances in the processes of attention, perception, thinking, memory. Slowing down of the processes of perception, a decrease in its brightness (in particular, the vagueness of visual sensations), difficulties in processing new information, difficulty concentrating, a high level of absent – mindedness are quite typical symptoms of depression .
In a depressed state, intellectual processes are inhibited, curiosity, inquisitiveness disappear, intelligence, resourcefulness, and ingenuity are lost. There are no ideas that can be called fresh. Any intellectual activity causes rapid fatigue. Fixation on one and the same thoughts, complaints, doubts resembles the stereotypical obsessive-compulsive disorder, “ruminations”. Speech is usually poor in words and slowed down. The person does not immediately answer the question, he is silent for a long time.
Sufferers are convinced that their experiences are inaccessible to the people around them, that it is no longer possible to help them . There is a certain suspicion of even relatives and friends, mistrust, doubts about their sincerity and honesty. At the same time , a person suffering from depression torments himself with thoughts about what he is making others worry about.
The present, the future, and sometimes, but to a lesser extent, the past are seen in dark colors. There is a conviction that the suffering is well deserved by the mistakes of a past life, that he is guilty and subject to punishment. Often these beliefs lead to strong religiosity, a desire for repentance.
One of the theories of “depressive thinking” identifies, in particular, such components as “a stream of negative thoughts” (for example, “I am untenable as the head of the family”), categorical thoughts (the belief that you can be happy only when you are loved by everyone).
Depression makes it difficult to memorize and assimilate new material, reduces the ability to fix current events in memory. Concentration of attention weakens, its volume narrows, information that is difficult to assimilate is poorly retained in memory. Forgetfulness appears, it becomes difficult for a person to concentrate on something.
These symptoms may partly be due to changes in biochemical processes in the brain.