Complex sentence: In particular, in addition to having more severe social phobia symptoms, patients with avoidant personality disorder are more depressed and have more functional impairment than patients with only generalized social phobia but show no differences in social skills or performance on an impromptu speech.
Split into simpler sentences: In particular, those with AvPD experience not only more severe social phobia symptoms, but are also more depressed and more functionally impaired than patients with generalized social phobia alone. But they show no differences in social skills or performance on an impromptu speech.