The heritability of depression is significantly lower than other mental illnesses such as schizophrenia. This suggests that majority of depression is secondary to environmental factors.

Screening

The following two questions can be used to screen for depression

• 'During the last month, have you often been bothered by feeling down, depressed or hopeless?'
• 'During the last month, have you often been bothered by having little interest or pleasure in doing things?'

A 'yes' answer to either of the above should prompt a more in depth assessment.

Assessment

There are many tools to assess the degree of depression including the Hospital Anxiety and Depression (HAD) scale and the Patient Health Questionnaire (PHQ-9).

Hospital Anxiety and Depression (HAD) scale

• consists of 14 questions, 7 for anxiety and 7 for depression
• each item is scored from 0-3
• produces a score out of 21 for both anxiety and depression
• severity: 0-7 normal, 8-10 borderline, 11+ case
• patients should be encouraged to answer the questions quickly

Patient Health Questionnaire (PHQ-9)

• asks patients 'over the last 2 weeks, how often have you been bothered by any of the following problems?'
• 9 items which can then be scored 0-3
• includes items asking about thoughts of self-harm
• depression severity: 0-4 none, 5-9 mild, 10-14 moderate, 15-19 moderately severe, 20-27 severe

NICE use the DSM-IV criteria to grade depression:

• 1. Depressed mood most of the day, nearly every day
• 2. Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day
• 3. Significant weight loss or weight gain when not dieting or decrease or increase in appetite nearly every day
• 4. Insomnia or hypersomnia nearly every day
• 5. Psychomotor agitation or retardation nearly every day
• 6. Fatigue or loss of energy nearly every day
• 7. Feelings of worthlessness or excessive or inappropriate guilt nearly every day
• 8. Diminished ability to think or concentrate, or indecisiveness nearly every day
• 9. Recurrent thoughts of death, recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide

Dementia

Factors suggesting diagnosis of depression over dementia

• short history, rapid onset
• biological symptoms e.g. weight loss, sleep disturbance
• patient worried about poor memory
• reluctant to take tests, disappointed with results
• mini-mental test score: variable
• global memory loss (dementia characteristically causes recent memory loss)

NICE produced updated guidelines in 2009 on the management of depression in primary and secondary care. Patients are classified according to the severity of the depression and whether they have an underlying chronic physical health problem.

Please note that due to the length of the 'quick' reference guide the following is a summary and we would advise you follow the link for more detail.

Persistent subthreshold depressive symptoms or mild to moderate depression with inadequate response to initial interventions, and moderate and severe depression

For these patients NICE recommends an antidepressant (normally a selective serotonin reuptake inhibitor, SSRI)

The following 'high-intensity psychological interventions' may be useful:


For people who decline the options above, consider:

• counselling for people with persistent subthreshold depressive symptoms or mild to moderate depression; offer 6-10 sessions over 8-12 weeks
• short-term psychodynamic psychotherapy for people with mild to moderate depression; offer 16-20 sessions over 4-6 months

For patients with chronic physical health problems the following should be offered:

• group-based CBT
• individual CBT