Psoriasis is not a contagious disease, but rather related to internal bodily factors, and therefore cannot be contracted through contact. It is mainly associated with abnormal immune system function, genetic factors, and environmental triggers. If you experience red patches or silvery-white scales on your scalp, it is recommended to seek medical attention promptly for a definitive diagnosis.

This can be understood from the following aspects:

1. **Impact of the Immune System**: An overactive immune system may accelerate skin cell growth, leading to the accumulation of keratin and the formation of scales.
2. **Genetic predisposition**: Some patients have a family history of genetic predisposition, but it is not absolutely hereditary; environmental factors also play an important role.
3. **Environmental triggers:** Such as stress, skin injury, infection, or certain medications may trigger or worsen symptoms.
For daily care, use gentle medical-grade shampoos and avoid scratching the scalp. Under the guidance of a doctor, combined with standardized treatments such as topical medications and phototherapy, most symptoms can be relieved. Maintaining a good sleep schedule and reducing mental stress also help stabilize the condition.