American Board of Psychiatry and Neurology (ABPN) Practice Exam 2026 - Free ABPN Practice Questions and Study Guide

The symptoms described—brittle hair, weight gain, and cold intolerance—are classic indicators of hypothyroidism. In this condition, the thyroid gland is underactive, leading to a reduction in the production of thyroid hormones. These hormones are critical in regulating the body's metabolism, energy levels, and overall bodily functions.

Brittle hair occurs due to the reduced metabolic activity affecting hair follicle health, leading to weakened hair structure. Weight gain is also commonly associated with hypothyroidism since a slower metabolism typically results in an inability to burn calories effectively. Cold intolerance is due to the body’s decreased ability to generate heat; thyroid hormones play an essential role in thermoregulation, and their deficiency can lead to a sensation of feeling cold even in normal temperature conditions.

While the other conditions listed can have overlapping symptoms, they do not typically present with the specific combination of brittle hair, weight gain, and cold intolerance. For example, major depressive disorder might entail weight gain but would more prominently feature changes in mood and motivation rather than hair quality or temperature sensitivity. Anxiety disorders might cause changes in appetite and could lead to gastrointestinal symptoms, but they don't specifically cause the hair and temperature issues seen in hypothyroidism. Diabetes mellitus can lead to weight changes and possibly