How would you explain sociopathic behaviour from a shastric point of view?

Any kind of behavior by a material body and mind can be categorized into the three modes of material nature.

This is explained by Krishna in Bhagavad Gita.

Krishna says:

O winner of wealth, now please listen as I tell you in detail of the different kinds of understanding and determination, according to the three modes of material nature. (Bg 18.29)

O son of Pritha, that understanding by which one knows what ought to be done and what ought not to be done, what is to be feared and what is not to be feared, what is binding and what is liberating, is in the mode of goodness. (Bg 18.30)

O son of Pritha, that understanding which cannot distinguish between religion and irreligion, between action that should be done and action that should not be done, is in the mode of passion. (Bg 18.31)

That understanding which considers irreligion to be religion and religion to be irreligion, under the spell of illusion and darkness, and strives always in the wrong direction, O Partha, is in the mode of ignorance. (Bg 18.32)

So to be a sociopath is basically the same as being a psychopath - a person with no sympathy for other living entities, a person bereft of empathy or understanding of other people, a person who inflicts violence on others, indiscriminately, a person with no remorse. IOW, a person in the extreme mode of ignorance.

In the mode of goodness, you know what is what, and you know what to do. And you recognize real religion.

In the mode of passion, you can’t distinguish between religion and irreligion. IOW, you are always in doubt, and can’t really see things as they are. You are more in illusion than a person in the mode of goodness.

In the mode of ignorance, you are not even in doubt, you are completely convinced, but of the wrong things. You think irreligion is religion, and vice versa. Like a Christian or a Muslim who is completely convinced that only their understanding of God is the right one.

Of course, the modes of nature are always mixed in a person. Religious persons usually have some moral and ethics they live by, they try to be good, so they are mixed passion and ignorance. But fanaticism is a product of tama-guna.

Thus, a sociopath or a psychopath - a person with no care of the consequences of his actions - is a person predominantly in tama-guna.

In the mode of passion you will at least doubt as to what is right or wrong. Doubting is a function of the intelligence, so your intelligence is still intact. In the mode of ignorance, the intelligence is completely covered.

And in the mode of goodness, one is also convinced, but of the right things, as ascertained by guru, sadhu, and shastra.

That means in the mode of goodness, the intelligence is clear, and guided by proper authority. In the mode of passion the intelligence is unclear and unguided. And in the mode of ignorance, there is no intelligence, at all.

Krishna says:

Material nature consists of three modes – goodness, passion and ignorance. When the eternal living entity comes in contact with nature, O mighty-armed Arjuna, he becomes conditioned by these modes.

O sinless one, the mode of goodness, being purer than the others, is illuminating, and it frees one from all sinful reactions. Those situated in that mode become conditioned by a sense of happiness and knowledge.

The mode of passion is born of unlimited desires and longings, O son of Kunti, and because of this the embodied living entity is bound to material fruitive actions.

O son of Bharata, know that the mode of darkness, born of ignorance, is the delusion of all embodied living entities. The results of this mode are madness, indolence and sleep, which bind the conditioned soul.

O son of Bharata, the mode of goodness conditions one to happiness; passion conditions one to fruitive action; and ignorance, covering one’s knowledge, binds one to madness.

Sometimes the mode of goodness becomes prominent, defeating the modes of passion and ignorance, O son of Bharata. Sometimes the mode of passion defeats goodness and ignorance, and at other times ignorance defeats goodness and passion. In this way there is always competition for supremacy.

— Bhagavad-gita 14. 5-10