has its own set of symptoms like anhedonia, anergia,decresaed sleep, appetite, lowered concentration and attention etc and at its peak of severity the person might have suicidal ideas. The symptom and severity vary with person to person. Having hopelessness and sadness alone won't put anyone to be depressed but they are part and parcel of the symptoms. Thyroid in medical condition put the person more into the condition of depression due to neurotransmitter imbalance. Please get the person treated by a psychiatrist
as depression is actually adverse to a healthy and happy life. CBT and mindfulness from a clinical psychologist
will also help as an adjunct, take care.